Note: Descriptions are shown in the official language in which they were submitted.
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USING SCATTERING FIELDS IN A MEDIUM TO REDIRECT WAVE ENERGY
ONTO SURFACES IN SHADOW
TECHNICAL FIELD
100011 The invention relates generally to injecting scattering
elements between a
source of EM/EL/QP wave energy and one or more target surfaces to increase the
dosage to surfaces in shadow, which can also improve the dosage uniformity
over
large surface areas of the target. The invention also discloses novel
dosimeters for
testing shadowed surfaces, called `dosimetric avatars.'
BACKGROUND ART
[0002] "The earliest scientific observations of the germicidal
effects of ultraviolet
radiation began with Downes and Blunt (1877) who reported that bacteria were
inactivated by sunlight, and found that the violet-blue spectrum was the most
effective." (Ultraviolet Germicidal Irradiation Handbook, ISBN 978-3-642-01998-
2)
[0003] Even so, it has been shown that the effective use of
Ultraviolet Germicidal
Irradiation (UVGI) on complex surfaces is still inadequate 144 years after the
germicidal effects of UV were first discovered. As well, shadows created by
objects in
the path of direct 11V cause inadequate disinfection of surfaces.
[0004] It is also important to note that the technologies of
UVC and
sprays/vapor/bubbles crossed paths, and yet there are no references to using
an
aerosol (including using an inert, pure water aerosol) to scatter UVC for
solving the
shadowing problem.
[0005] The issue of shadows in UVGI has been known for more than 80 years,
i.e., a long-felt but unsolved need.
[0006] Accordingly, it may be possible to achieve incremental
log-reduction in
disinfection that is important enough in terms of human illness or economic
impact
to make a change to an existing approach.
[0007] Also, it is well known that there is no standard test for UVC
dosimetry of
shadowed/shielded surfaces. Traditional dosimeters are flat, and at-best have
been
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used as appliques on complex surfaces, although this does not account for
microtextured surfaces like that of a strawberry, for example.
[0008] Inoculation of actual inicrotextured surfaces has been
utilized to test
fluence, but this is time consuming, expensive, and requires a certain level
of
expertise in microbiology.
DISCLOSURE OF THE INVENTION
[0009] A concise summary can be found in Applicant's
presentation at the 07-
Jun-2021 IUVA 2021 World Congress conference, incorporated in the '349
provisional application filed on 05-Jun-2021. The presentation is entitled
Increasing
UV Dosage on Surfaces in Shadow Using a Dry Fog of Water Droplets as a Light
Scatterer. IUVA is the International Ultraviolet Association (Bethesda, MD).
[0010] The instant invention comprises two primary
embodiments. One
embodiment teaches the use of scattering particles to improve wave energy
dosage
uniformity, including reaching surfaces in shadow and compensating for non-
uniform
illumination. Another embodiment relates to the construction and use of 3D
surface
dosimeters, called `dosimetric avatars', that better characterize the dose
received by
actual 3D objects. Applications include 3D dosimeters (of different levels of
complexity) that look and act like strawberries or other objects that
historically have
been difficult to treat with UVGI due to their surface texturing/shadowing.
The 3D
dosimetry provides, e.g., feedback for optimizing fluence for existing
disinfection/non-disinfection systems and the scattering approach taught
herein, as
well as providing quality control checks along a production line. Both primary
embodiments are contemplated for use in any phase/state of matter, including
in
gaseous media (e.g., droplet/particle scattering) as well as liquid media
(e.g.,
bubble/particle scattering).
BRIEF DESCRIPTION OF THE DRAWINGS
100111 A concise set of drawings are presented herein,
selected from a much larger
set filed in the provisional applications.
[0012] Figure 1 shows a UVC tunnel application disinfecting strawberries
with dry
fog injected from the top of the unit towards the conveyor belt.
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[0013] Figure 2 shows microorganisms, 'fluence multiples', and
rate constant
comparison for Water, Surface, Air-Lo RH and Air-Hi RH.
[0014] Figure 3 shows Monte Carlo multiparticle scattering
simulations for a
4.85" thick cloud of dry fog at a concentration of 100,000 droplets per cm3
for four
different droplet sizes, each at vacuum wavelengths of 222nm (far-UVC) and
730nm
(far-red).
[0015] Figure 4 shows Monte Carlo simulations at the
germicidal vacuum
wavelength of 254nm for 5 droplets and at fog thicknesses of 3.85" and 5.85",
each
at four different dry fog concentrations.
[0016] Figure 5 was created to show a microbe in a canyon (not to scale),
without
fog, having no direct line-of-sight to the rays from any of the UVC lamps that
line
the top of the drawing.
[0017] Figure 6 shows the microbe in Figure 5 using exemplary
MontCarl ray
trace renderings from Figure 4, with UVC lamps/rays in the extended field of
view.
100181 Figure 7 shows a UVC transmissive rectangular box that contains dry
fog
and objects to be disinfected, riding through a UVC tunnel.
[0019] Figure 8 shows a food powder (e.g., wheat flour) being
treated with UVC
using dry fog isolated from the powder.
[0020] Figures 9a and 9b show UV grade optical fibers/rods
(e.g., end-emitting or
side-emitting depending upon the application) formed in a thin sheet
interspersed with
manifolds fitted with nozzles/perforations to emit scattering elements.
[0021] Figure 10 shows the visible light fog chamber setup
(cross sectional
elevation view).
[0022] Figure 11 shows visible red laser light scattering
measured in the chamber
of Figure 10, compared to Monte Carlo results.
[0023] Figure 12 shows MontCarl Monte Carlo scattering results
for a 635nm 10
HWIlM laser, with a 385mm scattering field length, using 1.8p radius droplets
from
concentrations between 0 and 1E5 mm-3 (1E8 cm-3).
[0024] Figure 13 shows the same as Fig. 12 except that the
concentration varies
from 1E5 nue (1E8 cm-3) and 1E6 mm-3 (1E9 cm-3).
100251 Figure 14 shows visible light scattering measurements
for various fog
thicknesses (based on different positions of the 4" PVC telescoping tube with
a black
inner lining) with one width of black vinyl tape used to shadow the sensor.
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[0026] Figure 15 shows the visible light fog chamber setup
(cross sectional
elevation view) for cross-illumination measurements.
[0027] Figure 16 shows cross-wise visible light dry fog
scattering at a fixed 10 1/4"
distance to determine scattering sensitivity to the position of the black-
lined 4" PVC
tube.
[0028] Figure 17 shows the effects of air pressure and flow
rate on fog scattering
from measurements with the HEART nebulizer.
[0029] Figure 18 shows plots from calculations of ultrasonic
water droplet size vs.
piezoelectric frequency.
[0030] Figure 19 shows plots from calculations of water droplet evaporation
time
as a function of droplet diameter and relative humidity.
[0031] Figure 20 shows cross-wise visible light dry fog
scattering at a fixed 10 1,14"
distance to determine scattering sensitivity to the fog exit apertures using
the setup of
Figure 15.
100321 Figure 21 shows the same as Fig. 20 except the secondary vertical
scale is
changed.
[0033] Figure 22 shows the visible light fog chamber setup
(cross sectional
elevation view) for measuring vertical fog height effects in the cross-
illumination setup
[0034] Figure 23 shows visible light scattering variations as
a function of vertical
height using the setup of Figure 22.
[0035] Figure 24 shows results from a custom CFD simulation of
dry fog
concentrations after exiting a pipe at time t=5.080 seconds.
[0036] Figure 25 shows the UVC test setup in the HomeSoap
unit modified for
use with and without dry fog.
100371 Figure 26 shows a MontCarl ray trace extracted from Figure 4
superimposed
on a detail of the modified HomeSoap UVC test setup to demonstrate how
scattered
light rays reach the shadowed upper UVC sensor.
[0038] Figure 27 shows UVC shadow' measurements with and
without fog from
the modified HomeSoap UVC test setup of Figure 25.
[0039] Figure 28 shows UVC 'direct-view' measurements with and without fog
from the modified HomeSoap UVC test setup of Figure 25.
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[0040] Figure 29 shows the temporal effects from both cold-
start and warm-start
cycles measured from the bottom UVC lamp in the modified HomeSoap UVC test
setup of Figure 25.
[0041] Figure 30 shows the temporal effects of fog scattering
measurements using
5 the upper UVC sensor facing the upper UVC lamp at a distance of 8.25",
with fog
injected at the 6 minute mark in 1 cold-start and 3 warm-start 10-minute
cycles in the
modified HomeSoape UVC test setup of Figure 25.
[0042] Figure 31 shows a block diagram that encompasses
features discussed in the
instant invention and is adaptable for use with EM, EL, and QP wave energy
scattering
in gas and liquid media.
[0043] Figure 32 shows parts to a Card 'humiSonic' ultrasonic
humidifier with 14
directable outputs.
[0044] Figure 33 shows the operating principles for the unit
in Figure 32.
[0045] Figure 34 shows the part numbering (with options) and
the 'basic
parameters' for the unit of Figure 32.
[0046] Figure 35 shows the 'service parameters' for the unit
of Figure 32.
[0047] Figure 36 shows parts to a Carel 'humiSonic Compact'
ultrasonic humidifier
with a single output connected to a hose and a distribution manifold.
[0048] Figure 37 shows installation guidelines and a fan-
shaped output diffuser for
the unit of Figure 36.
[0049] Figure 38 shows the alarms for the unit of Figure 36.
BEST MODES FOR CARRYING OUT THE INVENTION
[0050] This invention relates to improvements in wave energy
irradiance systems
for use in dosing objects (organisms and inanimate objects) that possess
kinetic
processes responsive to fluence (or dose), i.e., the combination of
irradiation over
time. This is found in ultraviolet light germicidal irradiation (UVGI) systems
(radiolysis, ultrasonication, etc.) for the purpose of disinfection or
decontamination
by reducing the number of pathogens by damaging DNA, proteins, etc. and
limiting
photo-repair/dark-repair). UVGI will be referenced in the bulk of this filing.
Other
exemplary applications that respond to the combination of irradiation over
time
include photosynthesis (increasing growth in response to visible and far-red
irradiation over time), photocuring/photopolymerization (UVA and other
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wavelengths) and light-activated tooth whitening. Many of these processes can
be
generalized under the categories of photochemistry (including microwave
chemistry)
and photophysics, See, e.g., Photochemistry and Photophysics - Concepts,
Research,
Applications (ISBN 978-3-527-33479-7), Category Photochemistry ¨ Wikipedia.
[0051] Wave energy as used herein includes irradiation from
electromagnetic,
EM (e.g., UV and visible light), elastic, EL (e.g., ultrasonics in fluids),
and/or
quantum particle, QP sources (e.g., electron beams), all of which can be
scattered.
Disinfection applications also use radiolysis via gamma rays (EM) and electron
beams (QP), and cavitation via ultrasonication (EL).
100521 For the purposes herein, the terms of dose and fluence will be used
synonymously as the combination of irradiance over time (unless defined
otherwise
in a particular context) applied to kinetic processes of objects (organisms
and
inanimate objects) responsive thereof. Objects having kinetic processes
responsive to
wave energy fluence are known to have kinetic rates that change with different
levels
dosing and/or irradiance, some due to damage at high fluences, some due to
shadows,
some due to more nuanced effects.
(00531 The field of invention relates to the overarching
tenets of Process
Intensification (PI), namely via more effective use of one or more of EM/EL/QP
wave
energy fluence to improve a kinetic process via efficient wave energy
scattering onto
surfaces (optionally in combination with other non-photochemical/photophysical
modalities with kinetic effects such as chemical, heat, etc.). The invention
also
teaches the construction and use of novel dosimeters called dosimetric avatars
to
characterize wave energy fluence received over smooth and/or complex surfaces.
Note that PI relates to those processes that are desirable to intensify,
although
improvements may come with undesirable side effects (e.g., a slight reduction
in the
quality of certain foods from UVGI).
100541 Note that surfaces receiving the fluence range from
microscopic (viruses)
to macroscopic (a plant leaf), as well as microscopic surfaces on macroscopic
objects
(microbial pathogens on either a spinach leaf, the textured surface of a
strawberry, or
a particle of wheat flour). Further, the wave energy may penetrate to some
distance
below the surface to have their effect on a kinetic process (DNA in a
microbial
pathogen within a biofilm attached to a strawberry, chloroplasts in
photosynthetic
cells within a leaf, adhesive molecules in a 3D adhesive-cured printed part).
In most
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UVGI embodiments herein, the instant invention improves the fluence
distribution
across macroscopic object surfaces in order to irradiate microscopic surfaces
that
may be hiding due to surface complexity (e.g., the 'canyon wall effect')
and/or to
homogenize non-uniform illumination. This is consistent with the use of
'surface
disinfection' when compared to air- and water disinfection.
[0055] As an aside, a quick primer on UVGI can be found in
Inactivation of
microorganisms by newly emerged microplasma UV lamps (2020), "In principle,
irradiated UV photons prevent microorganisms from replication and survival, so-
called inactivation, by changing their genetic nucleic acid structure [4],
either
ribonucleic acid (RNA) or deoxyribonucleic acid (DNA). In practice, however,
two
types of microorganisms have challenged the further globalization of the
currently
available UV sources: microorganisms with (i) UV-resistant genomic structure
and
(ii) effective post-irradiation repair mechanisms for nucleic acid lesions,
which are
designated hereafter by UV-resistant microorganisms (URMs) and effectively
repairable microorganisms (ERIVIs), respectively. These microorganisms lead to
a
higher required UV-dose regulated by global environmental protection agencies
for
adequate disinfection by UV sources, which, in turn, results in higher energy
consumption and lower process efficiency. Further, the regulations sometimes
require the addition of chemical disinfectants, such as chlorine and ozone, as
supplementary disinfectants, defecting the purpose of the sustainable
"chemical-free"
UV treatment. Sensitivity of nucleic acid protection and viral proteins in
URMs for
UV with below 240 nm photons, known as far-UVC radiation [5] (see Scheme Si
for
partitioning of UV radiation), can be the key to increasing susceptibility by
inducing
damage to these components. In ERMs, the repair mechanism to maintain genome
integrity consists of two main phenomena: intrinsic nucleotide excision repair
[6] and
light-initiated [7] repair, which are known as dark repair and
photoreactivation,
respectively. In photoreactivation, the repair is performed by an enzyme,
called
photolyase [8], which reverses UV-induced damage in nucleic acids. In dark
repair,
the damage is reversed by the action of a number of different enzymes. All of
these
enzymes are activated by an energy source which could be photons mainly in the
wavelength range of 300-500 nm for photoreactivation, or existent nutrients
within
the cell for dark repair [9]. Inactivating radiation at a broad range of UVCs
has been
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claimed to be effective for reducing subsequent reactivation of microorganisms
[7,8]."
100561
"UVGI is also used to distinguish air and surface disinfection
applications
from those in water (CIE 2003). The design of UV systems for water
disinfection
differs from that of air and surface disinfection applications and therefore
the
cumulative knowledge accrued in the water industry is of limited direct use
for air
and surface disinfection applications. UV rays are attenuated in water and
this
process has no parallel in air disinfection, even with saturated air. The
attenuation of
UV irradiance in water occurs within about 15 cm and this necessitates both
higher
UV power levels and closely packed arrays of UV lamps. The estimates of UV
doses
required for water disinfection are on the order of ten times higher than
those needed
in air disinfection applications, and this difference distorts any attempt to
use water
UV system sizing methods to design air disinfection systems. Furthermore, the
array
of particular microorganisms of concern in the water industry differs
considerably
from those found in air and therefore water-based UV rate constants are of use
only
where the microbial agent is both airborne and waterborne (i.e. Legionella),
or is also
surface-borne, and for theoretical analysis. Some overlap in waterside and
airsick I.TV
applications also exists in the area of foodborne pathogens, where certain
foodborne
pathogens may become airborne, and where they may exist as surface
contamination
amenable to UV disinfection. Although the UV exposure dose in air is a simple
function of airflow and exposure time, and the UV irradiance field in air is
not too
difficult to define, the susceptibility of airborne microbes is a complex
function of
relative humidity and species-dependent response. It has often been thought
that the
UV susceptibility of microbes in air at 100% relative humidity (RH) should
correspond to their susceptibility in water, but this proves to be overly
simplistic and
it can only be said that UV susceptibility at high RH approaches that in
water. As a
result of these various differences between water-based UV disinfection and
UVGI
air and surface disinfection, research into the former provides limited
benefits to
research into air-based disinfection, and the subject of water disinfection is
not
addressed in this book except insofar as it has some specific impact on air
and
surface disinfection and in the matter of their common theoretical aspects.
One of
the main differences between air and surface disinfection with UV is that the
relevant
UV rate constants differ under these two types of exposure ¨ airborne rate
constants
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tend to be higher in air, under normal humidity. That is, microbes are more
vulnerable in air, whereas microbes on surfaces appear to have a certain
degree of
inherent protection. Although the matter remains to be resolved by future
research,
the available database for UV rate constants for microbes on surfaces is
useful as a
conservative estimate of airborne rate constants, as are water-based rate
constants,
whenever airborne rate constant studies do not exist ... An alternate or
additional
explanation for the decrease in UV rate constants with RH observed for some
microbes is that the absorption of water and the layers of bound water that
form at
high RH produces a protective effect due to the increased scattering of UV
light
waves. Higher RH may also increase clumping, which may also impact light
scattering as well as provide photoprotection to internal cells. For a
particle that is
already near the size range for Mie scattering, any increase in the size of an
airborne
microbe, whether due to swelling from water absorption or from clumping could
cause a major change in the amount of absorbed UV radiation" (Ultraviolet
Germicidal Irradiation Handbook UVGI for Air and Surface Disinfection, ISBN
978-
3-642-01998-2)
[0057] An exemplary (and non-limiting) application discussed
throughout this
application relates to ultraviolet (UV) light germicidal irradiation (UVGI)
for the
reduction of pathogens. Ultraviolet light is characterized in three wavelength
bands ¨
A, B, C, and are referenced throughout as LTVA, UVB, and UVC, respectively.
Most
references to UVGI cite UVC (generally between about 220nm and 280nm),
although
germicidal action has been noted into the longer wavelengths of the visible
spectrum
as well, albeit at lower efficacies.
[0058] "The earliest scientific observations of the
germicidal effects of ultraviolet
radiation began with Downes and Blunt (1877) who reported that bacteria were
inactivated by sunlight, and found that the violet-blue spectrum was the most
effective." (Ultraviolet Germicidal Irradiation Handbook, ISBN 978-3-642-01998-
2)
[0059] "It is well documented that impinging on simpler-to-
profile smoother
surfaces, like stainless steel or packaging, germicidal light at a specific
wavelength
can achieve 3- to 5-log reductions depending on the target organisms and
dosages
applied. But under same conditions for complex mixed material food surfaces,
only a
range of 0.5- to 2.5-log microbial reductions tend to be achieved." (Bayliss,
et al,
UVA Food and Beverage Safety Working Group, Are Food Contact Surfaces Seeing
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the Light?, UV Solutions Q1 2021 magazine, pgs. 12-13, Peterson Publications
inc.,
Topeka, KS).
[0060] "UV-C is a line of sight technology; it will not
penetrate deep into
crevices or layered surfaces. Workarounds for surface disinfection could
include
5 moving the UV source to avoid shadowing, unfolding portable reflectors,
or
installation of multiple sources. In commercial buildings, UV-C has been used
successfully for decades to disinfect moving air, both in HVAC ducts and in
upper
room applications." Seeking New Weapons Against Microbial Foes (Brons, et al,
LD+A Magazine, 2021 April, pgs. 58-61, Illuminating Engineering Society, New
10 York, NY)
[00611 Thus, the effective use of UVGI on surfaces is still
inadequate 144 years
after the germicidal effects of UV were first discovered.
[0062] The technologies of UVC (and other wave energy),
scattering, and
aerosols/bubbles/fogs/sprays/vapor have crossed paths as will be shown in what
follows. An aerosol is a field of fine solid particles or liquid droplets in
air or
another gas. The breadth of these references is not meant to suggest that one
of skill
in the art would have known to even search for many of these Most of these
references were found after substantial learning about the complex subject of
scattering as it applies to the instant invention. An objective method towards
gauging
this complexity is to review the 1000+ pages of provisional filings in the
instant
invention (vis-a-vis the absence of much of the information in the following
references), as it relates to the theory; simulation, build, and optimization
in order to
practice the invention, and then arrive at the test results disclosed, e.g.,
where in one
exemplary test, the UVC irradiance at a surface in shadow (indirect
irradiance)
received 242% more UVC when using dry fog scattering than when using no dry
fog
scattering (Fig. 27), while maintaining a high level of direct view irradiance
(Fig.
28).
[0063] UV with scattering bubbles (e.g. CO2) for liquid/water
treatment:
EP2443066A1 Method and device for treatment of water by exposure to UV
radiation, DE102006009351B3 Device for processing and discharge of fresh water
and water comprises a storage tank, a sterilization zone, a switch valve unit
that can
be switched between beverage discharge and feedback states, and a beverage
dispensing point and pump, JP2018192451A Sterilizing apparatus and hot water
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supply apparatus, W02018037938A1 Running water sterilization device and
running
water sterilization method, JP2012040505A Liquid treatment device, Comparative
study of PFAS treatment by UV. UV ozone. and fractionations with air and
ozonated
air, Decomposition Rate Of Volatile Organochlorines By Ozone And Utilization
Efficiency Of Ozone With Ultraviolet Radiation In A Bubble-Column Contactor.
[00641 Scattering due to bubbles for other applications:
Effect of air bubble size
on cavitation erosion reduction, Experimental study of aerated cavitation in a
horizontal venturi nozzle, Laser Scattering of Bubble in Water, The Volume
Scattering Function and Models for Scattering, Ozone chemistry _in aqueous
solution -
Ozone decomposition and stabilization, Quantifying The Effect Of Humidity On
Aerosol Scattering With A Raman Lidar, Non-line-of-sight ultraviolet single-
scatter
propagation model.
[0065] Humidifiers with a UVC source to disinfect the source
water prior to
dispersal as humidified air into the environment: US9482440 Humidifier with
ultraviolet disinfection, US7540474 UV sterilizing humidifier, US20100133707
Ultrasonic Humidifier with an Ultraviolet Light Unit, STULZ Ultrasonic
Humidification & EC Fan Retrofit Kit, Implementation and impact of ultraviolet
environmental disinfection in an acute care setting.
[0066] Decorative illumination of mist/fog/smoke emission:
US6301433
Humidifier with light, US7934703 Mist generator and mist emission rendering
apparatus, Theatrical smoke and fog - Wikipedia, US20170079110 Led module for
aerosol generating devices, aerosol generating device having an led module and
method for illuminating vapour.
100671 UVGI and humidity: Effects of Relative Humidity on the
Ultraviolet
Induced Inactivation of Airborne Bacteria, Far-UVC light - A new tool to
control the
spread of airborne-mediated microbial diseases.
[0068] UV to gel droplets expelled from an atomizer
apparently for use on the
skin of patients: US20170274159 Fluid delivery devices and methods.
[0069] Plasma in a vapor, with electrons and UV from the
plasma used for
disinfection: Features of Sterilization Using Low Pressure DC Discharge
Hydrogen
Peroxide Plasma, Cold plasma decontamination of foods (Annual review of food
science and technology 3 (2012): 125-142)
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[0070] Bioreactors using light scattering schemes such as wave
guiding
structures and bubbles: Engineered surface scatterers in edge-lit slab
wavqtuides to
improve light delivery in algae cultivation, Photon manav,ement for augmented
photosynthesis, Bioreactors for Microbial Biomass and Energy Conversion (ISBN
978-981-10-7676-3).
[0071] UV and disinfectant sprays/fogging, but not cited as
being performed
simultaneously, or involving scattering: COVID-19 ¨ JLM Environmental, Dry F02
and UVC light Disinfection Robot: SIFROBOT ¨ 6.62; An overview of automated
room disinfection systems - When to use them and how to choose them,
Implementation and impact of ultraviolet environmental disinfection in an
acute care
setting, Evaluation of 6 Methods for Aerobic Bacterial Sanitization of
Smartphones,
AOP for Surface Disinfection of Fresh Produce From Concept to Commercial
Reality UV Solutions, Innovative application of ultraviolet rays and
hydrogen
peroxide vapor for decontamination of respirators during COVID-19 pandemic- An
experience from a tertiary eye care hospital , US8084394 Method for the
control of
harmful micro-organisms and insects in crop protection with means of dipole-
electrical air-jet spray-technology, 070nated water and ITV-C irradiation,
Omni Aire
1200PAC, (Puro Rot) (Sani Rot), United Now Cleaning Flight Decks with UVC
Lighting - Aug 6, 2020, US20200405895A1 Device for disinfecting pipelines,
containers and structures.
[0072] UVGI with scattering from solid/encapsulated surfaces:
Ultraviolet
Germicidal Irradiation Handbook UVGI for Air and Surface Disinfection (ISBN
978-
3-642-01998-2) Fig 20.5 and associated text, US7511281 Ultraviolet light
treatment
chamber, US20190047877 A fluid purification system and method, US10517974
Ultraviolet surface illumination system US10604423 Method, system and
apparatus
for treatment of fluids, US9259513 Photocatalytic disinfection of implanted
catheters.
[0073] Scattering in (UV activated) photocatalytic and bubble
column reactors:
JP2001269541A Photocatalytic treatment device, Photocatalvtic Reactor Desi an -
Guidelines for Kinetic Investigation, Bubbles scatter light, vet that doesn't
hurt the
performance of bubbly slurry photocatalytic reactors (ABSTRACT), Design of
Photocatalytic Reactors ¨ see Chapter 3, apparently the same as the above
paper
Bubbles scatter light, yet that doesn't hurt the performance of bubbly slurry
photocatalytic reactors (a common author), Monte Carlo simulation of the light
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distribution in an annular slurry bubble column photocatalvtic reactor, CFD
Analysis
of the Radiation Distribution in aNew Immobilized Catalyst Bubble Column
Externally Illuminated Photoreactor, A Review of Physiochemical and
Photocatalytic
Properties of Metal Oxides Against Escherichia Coli.
[0074] UV scattering due to water film/droplets on a surface: US9044521 UV
sterilization of containers.
100751 Scattering as a function of relative humidity (RH):
Measurement of
relative humidity dependent light scattering of aerosols
100761 Long-felt but unsolved need - As shown below, the issue
of slows on
surfaces in UVG1 goes back at least as early as in US2231935 Sterilizing
cabinet for
glasses, dishes, and the like (filed Aug-1938, Col. 1/1-3 and Col. 4/48-54):
"My
invention relates to a cabinet designed and adapted to sterilize glasses,
dishes and the
like by means of ultra-violet radiation. ... whereas if any elements capable
of casting
a shadow were in contact with the lip area of the glass they would not only
intercept
the effective action of the bactericidal rays thereon, but by contact
therewith would
prevent the glass becoming completely sterile at that point."
[0077] More than 80 years later, shadows are still an issue-
"Significant
complexity is introduced when developing validation protocols for UV
disinfection
of surfaces due to the wide array of potential surface textures and/or
geometries of
items that commercial and consumer UV disinfection products are used to
disinfect.
Original research presented by Jaffe et al. at the 2020 lUVA Americas
Conference
demonstrated the "Canyon Wall Effect." Consider a minimally textured surface
with
"valley" depths only 1/10th of a human hair, or about 10 microns. The size of
the
SARS-CoV-2 virus is 0.15 microns. This is the equivalent of a supine person
sunbathing in a canyon with 1,000-foot walls. Just as the morning sun cannot
reach
the canyon floor, UV applied perpendicular to the surface will not reach into
the
crevices of a textured surface, allowing germ survival. ... Ultimately, the
dose
distribution will govern the efficacy of any UV disinfection system. For air
disinfection, this will be governed by the interplay between fluid mechanics
and the
fluence rate field. For surface disinfection, the interplay of the fluence
rate field, the
optical properties of the surface material, and surface texture ("shadowing")
are
likely to govern the dose distribution." Validation Needed for UV Surface
Disinfection Applications (02-Dec-2020, UV Solutions Magazine)
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100781 "The problem is illustrated by what's called the
"canyon wall" effect. To
bacteria and viruses, textural features on common surfaces can be like 100-
meter-
deep canyons would be to us. In experiments with surfaces having submillimeter
texture, UV-C's kill rate against the bacteria Staphylococcus aureus varied as
much
as 500-fold depending on the angle at which the mercury lamp's light fell.
That
dependence on angle is why it typically takes three UV systems to disinfect a
hospital room, according to Marc Verhougstraete, assistant professor of public
health
at the University of Arizona. Even then, there are still unexposed areas. So
for that
application, UV-C surface sanitizers should be part of a system that includes
routine
surface disinfection, hand hygiene, and air treatment, he says." (Anderson, M.
"The
ultraviolet offense: Germicidal UV lamps destroy vicious viruses. New tech
might
put them many more places without harming humans." IEEE Spectrum 57.10(2020):
50-55).
100791 Currently, methods to address the shadowing issue are
as follows:
[00801 The first approach is to change the angles of the light that reach
the
surface, i.e., by inducing relative movement between the source of wave energy
and
the target surfaces (without the use of scattering) This surely can be
helpful, but is
not always sufficient, it risks damaging the product (e.g., see 'Bruising'
below), and
not everything to be disinfected (processing equipment & product) can be
easily
rotated. With some products, even if they are rotated, there are still
shadows. "... to
enhance avoidance of shadowing, vibration or rotation of the objects may be
used
during the exposure, aiming to shake the target surface further into the line
of sight of
the sources. However, if the surfaces being treated are small enough ¨ such as
yogurt
cups ¨ solution engineers instead opt to pass them through a relatively slowly
moving UV-C tunnel conveyor system as a technique to overcome the amount of
shadowing present on the target surface due to static methods." (Bayliss, et
al, IUVA
Food and Beverage Safety Working Group, Are Food Contact Surfaces Seeing the
Light?, Mar-2021, UV Solutions Q1 2021 magazine, pgs. 12-13, Peterson
Publications Inc., Topeka, KS).
100811 Bruising - "The uniformity of the UV-C dose distribution is also an
important factor for the successful implementation of UV-C treatment. Many
researchers ensured the uniformity of the dose distribution by employing
manual
rotation of fruits. However, this method is not suitable for strawberries,
which have a
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soft surface, because it may cause bruising." Simulation of UV-C Dose
Distribution
and Inactivation of Mold Spore on Strawberries in a Conveyor System , citing
Simulation of LTV-C Intensity Distribution and Inactivation of Mold Spores on
Strawberries. "Ideally, fruit should be rapidly and randomly rotated in
multiple
5 planes, allowing all surface exposure from multiple directions and angles
of the UV
light ... applicable to other geometrically round fruit, such as peaches,
apricot, orange
etc. as long as the fruit can be rapidly and randomly rotated in multiple
planes without
causing mechanical damage. ... roller conveyers where fruit are rapidly
rotated.
Whether currently-used packing lines are capable of generating enough rotation
to
10 ensure uniform UV exposure needs further evaluation" Radiochromic film
dosimetry
for UV-C treatments of apple fruit, also stating
[0082] The second approach: "Water-assisted UV-C treatment,
two-sided and
tumbling UV-C apparatus may minimize the shadowing effect. Future research may
focus on commercial applicability of the technology for food surface
15 decontamination with efforts to reduce dose variation and shadowing
effect." (Fan, et
al, Application of ultraviolet C technology for surface decontamination of
fresh
nroduce, Trends in Food Science & Technology 70 (2017)- 9-19.).
[0083] " ... microorganisms on a food surface must directly
face a UV lamp to be
inactivated (Shama, 1999). To overcome this UV limitation, a water-assisted UV
system was developed in this study where blueberry samples were immersed in
agitated water during UV treatment. The blueberry samples could randomly move
and rotate in the agitated water, thus allowing all blueberry surfaces to be
exposed to
UV light and receive more uniform UV exposure. In the meantime, the vigorously
agitated water would wash off microorganisms on blueberry surfaces into water
(Pangloli and Hung, 2013), which could be easily killed by UV light since UV
can
penetrate well in clear liquid." However, "Water-assisted UV treatment was
generally more effective in inactivating MNV-1 skin-inoculated onto
blueberries
than the dry LTV treatment. The water-assisted UV treatments were more
effective
than or as effective as the 10-ppm chlorine washing. MNV-1 skin-inoculated
onto
blueberries was easier to be inactivated than that calyx-inoculated onto the
berries.
The presence of 2% blueberry juice in wash water provided protection for MNV-1
from both water-assisted LTV and chlorine wash treatments." (Liu, et al.
Application
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of water-assisted ultraviolet light processing on the inactivation of murine
norovirus
on blueberries, International journal of food microbiology 214 (2015): 18-
23.).
[0084] So organic material from the targets entering the wash
water, like
blueberry juice in the above example, can actually lower the efficacy of
disinfection.
Yet another risk is that "Pathogens can transfer from contaminated to
uncontaminated produce, and pathogens can be spread among batches if wash
waster
is reused and no proper invention is employed (21)." (Guo, et al, Evaluating a
combined method of UV and washing for sanitizing blueberries, tomatoes,
strawberries, baby spinach, and lettuce, Journal of food protection
82.11(2019):
1879-1889.) "In fact, one of the challenges of the produce industry in the
U.S. has
been monitoring the effective sanitation of product wash water." Microbial
Safety of
Fresh Produce (Institute of Food Technologists Series, ISBN 978-0-8138-0416-
3).
[0085] Even with the advantages of product movement in wash
water, surface
texture can have shielding effect: "We found that the levels of bacterial
reduction
due to WPL treatment varied with different topographies of berry surface
(Tables 1-
4). The presence of achenes of strawberries and the drupelets of raspberries
can
potentially shield microorganisms from the P!. beams, leading to only partial
decontamination. A similar phenomenon has also been observed in many other
studies (Belliot et al., 2013; Bialka & Demirci, 2008; Fino & Kniel, 2008)."
(Huang,
et al, Inactivation of Escherichia coli 0157: H7, Salmonella and human
norovirus
surrogate on artificially contaminated strawberries and raspberries by water-
assisted
Pulsed light treatment, Food Research International 72 (2015): 1-7., WPL =
"water-
assisted pulsed light."). Moreover, with respect to UVC using wash water,
certain dry
food items requiring disinfection are not amenable to moisture. See, e.g.,
Persistence
and survival of pathogens in dry foods and dry food processing environments.
[0086] The third approach is to utilize an additional non-
photochemical/photophysical modality with kinetic effects, such as chemical
disinfectants, in addition-to UVC. This can be efficacious if the
risks/concerns of
using chemicals are considered. Other modalities that have been combined with
UVG1 include temperature/heat-processing, pressure, ultrasound either
simultaneously or sequentially, RF/pulsed electric field, ozone, etc. Note
that not all
modality combinations referenced above are found to be synergistic, where the
sum
is more than the parts. Note that the use of the scattering of the instant
invention can
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enhance (or be enhanced) by the use of one or more additional modalities
(e.g., using
H202 in the scattering source water), whether used simultaneously and/or
sequentially (pre and/or post). The proper use of chemical agents is
referenced, e.g.,
in Refer to Guideline for Disinfection and Sterilization in Healthcare
Facilities, 2008,
Cleaninu, in place (CIP) in food orocessing, Fresh-cut product sanitation and
wash
water disinfection: Problems and solutions.
[0087] A fourth approach is to increase the dosage by
elevating irradiation
intensity and/or extending irradiation time. Generally, this also helps,
however too
high a fluence can lead, e.g., to damage to the quality of fruits and
vegetables. See,
e.g., Use of UV-C light to reduce Botrvtis storage rot of table grapes. Also,
in certain
applications, an increase of power does not always lead to a commensurate
increase
in efficacy due to 'shoulder' and/or 'tailing' effects, or photosaturati on in
photosynthetic plants. Added time under irradiation has the downside of
affecting
factory throughput.
[0088] Incomplete disinfection in the food industry has both financial
impact
(productivity losses from remediations/recalls, yield loss due to fruit
spoilage and
plant disease) and human impacts Parasitic disease yield losses for specific
fruits and
vegetables are cited in Reduction of losses in fresh market fruits and
ve.etables.
Enumeration of the financial impact (in the $ billions for all loss-mechanisms
including 'microbial growth' and the costs of pesticide use) of fruit and
vegetable
losses (from 2008) are discussed The Value of Retail- and Consumer-Level Fruit
and
Vegetable Losses in the United States. Annual financial losses due to
pathogens in the
grape industry are discussed in Result of a Survey on Grape Breeder's
Perceived
Priorities in Grape Genetics Research (2012). "US estimate is that there are
76
million foodborne illnesses annually, resulting in 325,000 hospitalizations
and 5200
deaths ... total cost estimates for STEC 0157 (i.e., Shiga toxin-producing
Escherichia
coli 0157) ... average cost for STEC 0157 is $6256 per case." The Economics of
Enteric Infections: Human Foodborne Disease Costs.
[0089] A fifth approach is the strategic placement of
reflectors - "It is difficult to
get uniformed UV-C doses for all surfaces of fruit when fruit are static even
with the
use of reflective material. Reflecting materials such as aluminum foil could
increase
irradiation doses on certain area on the surface of apples by reflecting UV-C
light.
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However, the reflection is limited in terms of the amount and direction"
Radiochromic film dosimetry for UV-C treatments of apple fruit
[0090] Failure of others - Below are shown excerpts from
recent publications
citing the failure of others to find a solution to the limitations of shadows
and
shielding (emphases added): "The designed system can treat any object which
fits
inside a sphere with a diameter of 250 mm, as long as its shape does not
induce any
shadows on other part of the structure (e.g., holes or pockets), irradiation
times have
been optimized for spherical targets and might require correction for objects
with
different shapes if the required fluence is not met on a specific area of the
target."
Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical
Irradiation Box - Design, Characterization and Validation, Apr-2021. "Pulsed
light
(PL) technology is a green, novel non-thermal technology that has huge
potential to
be employed for decontaminating food- and food-contact surfaces as well as
packaging materials. ... However, PL cannot be used to sterilize food products
due to
their non-uniform surfaces and opacity, except to reduce their microbial load.
Nevertheless, Pt. is one such technology, which has the capacity to tackle the
undesirable effects of conventional thermal processing. PT. is an apt method
of
decontamination for the surface of foods, packaging materials, equipment, and
clear
liquids. However, a challenge lies in the processing of particulate foods like
grains,
spices, and products having highly uneven surface due to the 'shadowing' of
microorganisms." (Mandal, Ronit, et al., Applications of pulsed light
decontamination technology in food processing: an overview., Applied Sciences
10.10 (2020): 3606.). "While PL was highly effective at reducing both viruses
and
bacteria in PBS suspension, its inactivation effectiveness varied with
different
topographies of berry surface and microorganisms (Table 2). In general, PL
treatment at fluence of 5.9, 11.4 and 22.5 J/ cm' were not significantly
different in
reducing microorganisms on strawberries, which suggested that shielding effect
is
the main factor that limit the inactivation." (Huang, et al., Pulsed light
inactivation of
murine norovirus. Tulane virus, Escherichia coli 0157: H7 and Salmonella in
suspension and on berry surfaces, Food microbiology 61(2017): 1-4.). "The
difference in efficacy of PL treatment against bacterial cells inoculated on
blueberry
skin and calyx in our study was probably due to the different surface
structures of
those two sites Compared with blueberry skin, the calyx has a much rougher
surface
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structure, which potentially allows more shielding/ shadowing of
microorganisms
inside surface details. It is known that PL has a very limited penetration
depth (w2
mm) in nontransparent media (Wallen et al., 2001) and is only capable of
targeting
superficial microorganisms. Therefore, bacterial cells hiding in the sub-
surface of the
calyx were probably protected from PL. Similar findings were reported by other
researchers. Kim and Hung (2012) observed a persistent higher population of E.
coli
0157:H7 recovered from the blueberry calyx than from the skin after UV
treatment.
Sapers et al. (2000) found a higher survival of E. coli in the calyx and stem
areas of
inoculated apples than the skin after a washing treatment. Woodling and Moraru
(2005) studied the influence of surface topography of stainless steel coupon
on the
effectiveness of PL treatment and indicated a complex effect of various
surface
properties on inactivation. Han et al. (2000) reported that E. coli 0157:117
preferentially attached to coarse and porous intact surfaces and injured
surfaces of
peppers. Similar phenomena were also exhibited by raspberries and strawberries
(Sy
et al., 2005). Indeed, higher levels of bacteria were reported to be found in
the calyx
of naturally contaminated apples (Riordan et al., 2001). The surface structure
of fresh
produce is usually complex and bacterial cells may lodge in surface
irregularities or
crevices, i.e., calyx, therefore, reducing the efficacy of PL by preventing
the highly
directional, coherent PL beam from reaching its target (Lagunas-Solar et al.,
2006).
Hence, great care must be taken in selecting the representative inoculation
site in a
microbial challenge study." (Huang, et al, A novel water-assisted pulsed light
processing for decontamination of blueberries, Food microbiology 40 (2014): 1-
8.).
[0091] Skepticism of experts ¨ the lossy effect of scattering
in the field of UVC
disinfection as cited by experts: "UVC energy follows the same inverse square
law
for intensity as visible energy and other electromagnetic sources: the amount
of
energy at the surface is measured in proportion to the square of the distance
from the
energy's source (UVC lamp), assuming no loss through scattering or
absorption."
(Chapter 62 - Ultraviolet Air And Surface Treatment (p/o 2019 ASHRAE
Handbook¨HVAC Applications (SI), ISBN 978-1947192133). "Transmittance
decreases in the presence of UV absorbing substances and particles that either
absorb
or scatter UV light. This results in a reduction of available UV energy for
disinfection." (Trojan UV3000Plus Reference Documents - City of Healdsburg).
"Turbidity is cloudiness or haziness in water that's caused by particles that
are
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generally invisible to the naked eye (such as organics, minerals, or
chemicals) This
will prevent the UV light from reaching microbes because these substances can
absorb or scatter UV light." (UV Pre-Treatment ¨ VIQUA).
[0092] Teaching against ¨ "It matters not whether the UV-C or
PX-UV light is
5 produced by Xenex, Tru-D or Clorox, they are all hampered by the same
laws of
physics and limitations, such as: Diminishing power over increasing distance,
Angle
of the exposed surfaces, Surface shadowing" (The UV Light Deception -
Altapure).
"Environmentally friendly & Biodegradable, when using a PAA agent. ...
Altapure's
patented technology produces a dense cloud of ultra small / sub-micron
aerosolized
10 droplets along with an active and constantly replenished vapor phase.
The technology
combines with the ability to achieve quick kill times within a window of less
than
forty-five (45) minutes start to finish (common patient room), while leaving
no
residue, and with only oxygen, water vapor, and vinegar vapor, as the end
products.
... Low %: Only 0.88% H202 & 0.18% PAA Non-Corrosive: safe for all
15 electronics ... 100,000+ Hospital Deploys With No Equipment Damage."
(Technology Background - Altapure) See the Altapure, LLC (Mequon, WT) website
for more information
[0093] Other background information that will be discussed
relates to fogs and to
dosimetry.
20 [0094] Fog background: Atmospheric fog and haze have been reported to
cover a
range of droplet sizes from about 0.1 to 201.t in diameter, and droplet
number
concentrations (Nd) from about 10/cm' to 104/cm" (Haze and Fog Aerosol
Distributions). Droplet sizes in the micron range can be found in steam/steam-
sterilizers, chemical foggers, humidifiers, fogponics/aeroponics, and fog-
based
projection screens. Dry fog is generally considered to comprise droplets less
than
about 101..t in diameter. Sources of dry fog include impingement devices
(using
compressed air and/or water, found in medical nebulizers and used in mining
for dust
suppression) and ultrasonic atomizers (e.g., operating in the MHz region, also
used in
medical nebulizers and humidifiers). Note that some impingement nozzles are
characterized as ultrasonic (e.g., HART Environmental's -035H pneumatic
'ultrasonic' impingement nozzle with a resonator cap), and ultrasonic devices,
when
looked at microscopically, can be considered to cause a type of impingement as
the
transducer surface slaps at the water more than a million times a second.
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00951 Dosimetry background: It is well known that there is no
standard test for
UVC dosimetry of shadowed/shielded surfaces. Traditional dosimeters are flat,
e.g.,
electrooptical pucks and photochromic indicators (stickers/cards), and at-best
have
been used as appliques on complex surfaces, although this does not account for
microtextured surfaces like that of "cantaloupe, strawberry and raspberry",
Application of ultraviolet C technology for surface decontamination of fresh
produce. Microbial inoculation of actual microtextured surfaces has been
utilized to
test fluence but this is time consuming, expensive, and requires a certain
level of
expertise in microbiology. Sources of supply are disclosed herein. Below find
references to dosimetry.
[0096] Traditional chemicals used in actinometry: See
Polychromatic UV Fluence
Measurement Using Chemical Actinometry. Biodosimetry. and NIathematical
Techniques, IUPAC Technical Report, Use of Potassium Iodide as a Chemical
Actinometer, and Validation of Large-Scale. Monochromatic UV Disinfection
Systems for Drinking Water Using Dyed Microspheres.
[0097] Dosimetry based on paper/cardboard and plastic
decals/substrates/films:
ITVC100-TRI dosimeter cards and UVC100-DOTS from Intellego
Technologies (Stockholm, Sweden), Quantitative UV-C dose validation with
photochromic indicators for informed N95 emergency decontamination, 3D Printed
Hydrogel-based Sensors for Quantifying UV Exposure, Radiochromic film
dosimetry
for UV-C treatments of apple fruit.
[0098] 3D volumeiric dosimeters: HEA-PVA gel system for UVA
radiation dose
measurement, Modus-OA-Product-Data-Sheet-ClearView-3D-Dosimeter, Ultraviolet
Light And The Imperfect Biological Indicator, UV intensity measurement and
modelling and disinfection performance prediction for irradiation of solid
surfaces
with UV light, CN104877147B The preparation method and application of PVA HEA
ultraviolet 3-dimensional dose meters (incl. EPO English translation),
US20040184955 Moisture resistant dosimeter, US20070020793 Three-dimensional
shaped solid dosimeter and method of use, US4668714 Molded dosimeter
containing
a rubber and powdered crystalline alanine, US5633584 Three-dimensional
detection,
dosimetry and imaging of an energy field by formation of a polymer in a gel,
US6218673 Optical scanning tomography for three-dimensional dosimetry and
imaging of energy fields, US6787107 Element with coated dosimeter, US6979829
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22
Devices and methods for determining the amount of energy absorbed during
irradiation, US7098463 Three-dimensional dosimeter for penetrating radiation
and
method of use.
[0099] Electrooptical radiometers: UV Cure Check and the
Power Puck II
(CureUV, Delray Beach, FL), UV512C (General Tools & Instruments, New York,
NY),
UV Clean (Apprise Technologies, Inc., Duluth, MN).
[00100] In Figure 1, strawberries ride along a conveyor belt inside a 'UV
tunnel'
that contains many UVC lamps illuminating them from above and below. UV
tunnels
are taught, e.g., in US6894299 Apparatus and method for treating products with
ultraviolet light, US20120141322 Uv sanitization and sterilization apparatus
and
methods of use. UV tunnels adaptable for the instant invention are available
from
JenAct Ltd (Whitchurch, Hampshire, United Kingdom), see UV Torpedo
Conveyor: Increasing product shelf life of fresh salmon fillets, as well as
from UV
Light Technology (Birmingham, England), Dillies Technologies GmbH
(Villingendorf, Germany), and ClorDiSys Solutions Inc (Somerville, NJ).
1001011 Referring back to Figure 1, dry fog is injected into the tunnel, and
the
resultant scattering illuminates the strawberries from a wider range of angles
than if
without fog. This can be seen by looking at the final angle of the two light
rays that
strike the strawberry on the left. The dashed lines trace back to locations
that could
not have come from a lamp directly, and that is how this technology reaches
the
shadows. Direct rays are available both with and without dry fog - see Figures
3 and
4, where in a fog, especially at lower number concentrations, some rays are
not
scattered but travel along the original light source trajectory. Due to the
scattering
action, a dry fog need only be 'radiantly connected' between the source and
target in
order for the target to receive scattered rays. Here 'radiantly connected'
means that
wave energy irradiation received at the target passed through some portion of
the
scattering field. Note that the dry fog injection is roughly between the lamps
and the
targets (strawberries). Stated differently, it can be said to be in the
'vicinity' of the
target surface, meaning the fog field can be in straight line between wave
energy
source and the target surface (employing forward scattering) and/or the fog
can be
near the target surface, such as off to the side or behind and not in a
straight line path
between the wave energy source and the target surface (e.g., employing the use
of
side scattering or backscafter). Thus, the vicinity means that the fog can be
radiantly
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23
connected to a target (and there can be gaps of low concentration near the
targets due
to ambient air flow and/or isolation layers). In some applications, the
distance from
wave energy source to the target may be a foot or so (e.g., in a UV tunnel),
in others
much longer (e.g., irradiating grape vines with UV in a vineyard, or
irradiating plants
with UV and far-red light in a greenhouse). In each case, the thy fog
concentration
can be adjusted to optimize the scattered light that reaches the targets over
a given
distance. As an aside, in a conveyor system, the target can be a strawberry,
but the
conveyor belt itself is also disinfected, whether intentionally or not, and
thus both are
in the vicinity of the dry fog.
1001021 To explain this, note first that the fog field is amorphous (unless
contained
mostly or totally by one or more walls such as an isolation barrier, the
enclosure of a
UV tunnel, air curtains, etc.) and can flow in sometimes unpredictable ways
(e.g.,
due to unforeseen air currents, which can also change the concentration
spatially/temporally). Second, depending on the target surface
characteristics, a given
application may benefit from injecting fog only along the sides of an object
(e.g., a
smooth topped object with textured sidewalls) with some even behind an object
(e.g.,
to backscatter the underside of an object on a wire link conveyor belt) Third,
in a
retrofit application, there may be structural limitations as to where fog can
be
injected, e.g., when disinfecting objects randomly placed in a hospital room
or
stimulating plants in a greenhouse with various building-related structural
elements
blocking portions of a fog field. In fact, portions of fog fields may never
receive
wave energy, e.g., at the spatial perimeters of the fog field where the
concentration
tapers-off into the atmosphere and thus no wave energy is directed there, or
on a
conveyor where wave energy is only directed in the vicinity of objects while
the fog
field is deposited across the entire conveyor belt for simplicity. Also, as
will be
discussed, it need not touch the lamps or targets (it can be isolated). The
scattering
aerosol field (also true for bubble field) is stochastic by nature, and as the
Monte
Carlo simulations here show, some rays pass through without being deflected by
a
scattering element (e.g., a dry fog droplet), while other rays deflect once,
and yet
others more than once. As such, not every scattered ray will strike the
target, and
some portion of the rays that strike the target will not reach a surface in
shadow. In
fact, in some applications, targets may be fl at and smooth, without shadows.
1 lere the
scattering action, if the atomizer feature is engaged for these targets (a
programmable
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24
version), provides enhanced fluence uniformity. In one set of embodiments, the
system is adaptable (in fog field concentration/geometry and/or wave energy
beam
intensity/geometry, spatially and/or temporally) based on one or more of a
simple
user switch, identification of the objects input via a touchscreen to the
control
system, and/or in-situ surface analyses using machine vision. As an aside, the
scattering system need not be physically connected to the wave energy portion
of the
enhanced dosing system. For example, in a UV tunnel application, it can be
housed
in a unit separate from the tunnel, with a scattering discharge hose that
injects fog but
does not touch the tunnel. In another exemplary application, a robotic system
can be
deployed with two separate robots, one to discharge scatterers, and the other
to
provide the visible and far-red wave energy to plants in a greenhouse.
1001031 The field can be viewed as a fluid, so it can be turbulent, laminar,
have
characteristics of both in different spatial locations (e.g., local eddies),
and can be
directed along swirling or other types of paths as described herein. In the
case of dry
fog, the droplets are subject to evaporation, coalescence, gravity, etc. as
described
herein With all of this, there will be spatial and temporal number
concentration
gradients See, e g , the CF1) simulation in Figure 24 In an exemplary
approach, the
scattering field is engineered to meet certain ranges of parametric
requirements by
adjusting its flow, the ambient temperature and RH, the number of atomizers,
etc. In
exemplary arrangements, the field is changed spatially and/or temporally.
1001041 In one exemplary embodiment, puffs or continuous streams of dry fog
are
injected in front of the strawberries as they travel along a conveyor system,
such that
the strawberry first receives direct irradiation, and then as is passes
through the
scattering field, it receives more and more indirect scattered irradiation. In
another
exemplary embodiment, the strawberries never touch the dry fog puff/stream but
pass
near or next to it (adjacent), so it receives direct irradiation from some
lamps, and
indirect from others. The dry fog field and the lamp(s)/target(s) can be
touching, not
touching, periodically touching, in contact with a different concentration
than another
part of the dry fog field, etc. It is important to realize that the fog field
has a
stochastic nature, and thus there is some amorphous quality that must be
considered
when trying to describe the geometric arrangement between the wave energy
source(s), the dry fog (or other scattering) field, and the target(s).
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[00105] =Note also that the dry fog scattered UV also disinfects the conveyor
belt
itself. Conveyor belt sterilization is disclosed in paragraph [0026] of
US20100243410 Method and apparatus for cleaning and sanitizing conveyor belts,
US8624203 Conveyor sterilization and US10933150 Conveyor belt sterilization
5 apparatus and method.
1001061 Shadows are caused at both the microscopic level comprising
cracks/crevices and surface textures. Individual viruses/bacteria/spores range
in size
from ¨0.02p, to ¨17.31.1, with collections of these individuals in a matrix
called
biofilms. Biofilms are called sessile when stationary and attached to a
surface. They
10 can also become planktonic or free-floating, which happens, for example,
when they
grow so large that a portion easily breaks off. Shadows also form at the
macroscopic
level via larger surface obstructions (textured surfaces and larger objects
obscuring
others). As an aside, unless otherwise specifically defined in a particular
context/reference, the term 'macroscopic' will be defined as 'visible to the
naked
15 eye', where the term 'microscopic' will be defined as 'invisible to the
naked eye.'
Adult visual acuity > 291.1. (a human hair is ¨ 750, thus, individual
viruses/bacteria/spores are microscopic. See What's the smallest size a human
eye
can see - Biology Stack Exchange Biofilms can be microscopic or macroscopic
depending upon the number of microbes and the amount of extracellular
polymeric
20 substance (EPS) that surrounds them (Materials and surface engineering
to control
bacterial adhesion and biofilm formation - A review of recent advances). Flour
particles appear to be macroscopic (Particle Size Analysis Of Two Distinct
Classes
Of Wheat Flour By Sieving).
[00107] The non-uniformities are due to uneven illumination resulting from
25 reactor optical design and variations along lamp lengths and between
lamps, with
variations increasing as they age (mercury lamps tend to darken with age).
Where
visible light diffusers are inexpensive and available in large sizes (polymer
based,
used in LCDTV backlights), UVC-transmitting optical diffusers tend to be small-
in
size and (very) costly, partly due to lower market demand, and partly due to
the lack
of low cost materials that efficiently transmit UVC. Commercially available
UVG1
luminaires have not been found with UVC transmitting diffusers.
[00108] The instant invention teaches the use of fog scattering as
an efficient
UVC transmitting diffuser (fogs based on larger wetting droplets can be used
if
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suitable for a given application, but for UVGI, dry fog will be considered),
lowering
the peak intensities and raising the valleys. The term 'dry fog' is used when
the
droplet sizes have a diameter of less than about 101.1.. When the dry fog is
directed to
surround an object to be disinfected, it forces a change in the angular
profile of the
UVC as seen from the surface of the object, reaching the shadows as shown in
Figures 1, 6, and 26. Note that a volume of dry fog is generally > 99% air: (%
Air in
a fog field) = 1 - (# of drops/volume) * (volume of a single drop). For
example, at a
number concentration, Nd of 1E7 droplets/cm3, the % air = 99.999%, 99.934%,
and
99.476% for ltt, 51.t, and lOtt diameter monodisperse, i.e., single size
droplets,
respectively. Moreover, both water droplets (e.g., deionized, distilled, tap)
of these
sizes, and air over reasonable distances, are very transmissive to UVC.
1001091 Key scattering parameters are dry fog droplet size, fog concentration
(which as will be shown may vary for a number of reasons), and fog thickness
(often
herein the generic word fog will be used instead of dry fog). The results of
many
Monte Carlo scattering simulations (using the program MontCarl as cited in
detail in
the TUVA presentation) will be shown to demonstrate the range of scattering
angles
and the transmittance and reflectance of the fog field to I.JVC (and other
wavelengths).
[001101 In a baseline configuration, the dry fog is generated using pure water
(no
chemicals) and works for visible light as well. As will be discussed, the
water can be
deionized, di stilled/demineralized, or simply potable tap water (with its
minerals and
any residual disinfectants used by the water company, or further treated at
the user's
facility). Dry fogs have been used for years in humidifiers 8z disinfectant
foggers
where 'wetting' is a concern.
1001111 Chemicals can be use instead-of or in-addition-to the water. The EPA
has
recently listed three COVID-19 Disinfectants suitable for fogging, all based
on H202
(see 'List N Tool: COVID-19 Disinfectants' on the EPA website, and search for
the
word log' to receive the latest update). One of these is discussed herein as
it relates
to cold plasma. Many other disinfectants are used, e.g., in outdoor
agricultural
foggers as well as in food processing plants and are also contemplated for use
with
the instant invention. Note that the effect of additives on droplet
evaporation time
should be considered.
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1001121 Dry fog is one to two orders of magnitude smaller than mists,
drizzles,
and raindrops. Note that fog atomizers (dry fog or other) tend not to be
monodispersed (single diameter), but polydispersed, comprising a distribution
of
diameters. As an aside, a more generic term for the artificial creation of
scattering
elements (dry fog or other) would be a generator. Note that 'artificial' is
used to
distinguish from scattering found in nature, e.g., atmospheric fog or bubbles
in a
crashing ocean wave. Artificial generators also supply, e.g., powder-type
scatterers
and bubbles from bubblers or via cavitation, e.g., from ultrasonic transducers
or
propellors). Dry fogs predominantly consist of droplet diameters < 10 ,
although
some distributions with tails out to ¨ 5011 are still considered dry fog if
the amount
beyond 10p is a small % of the overall output.
1001131 Based on the Monte Carlo simulations shown in Figure 3, a wide variety
of EM light sources can be used to scatter dry fog, including from the far UVC
(200-230nm) out to the far-red (sometimes called the near infrared, ¨ 730nm),
both
narrowband (e.g., Excimer lamp, LEDs, LP mercury lamps) and broadband sources
(fluorescent lamps, pulsed Xenon lamps, and MP mercury lamps). This was a very
slirpri sing and unobvious result.
1001141 A key characteristic of fog is its droplet number concentration
(sometimes
called number density or particle concentration), referred to herein as Nd,
which for
standard medical nebulizers are on the order of 106 or 1-million dry fog
droplets per
cm'. There are two basic dry fog atomizer technologies - impingement
(colliding
pressurized air with water, with different air flows and pressures as shown in
Figure
17, termed herein a pneumatic atomizer, or by colliding two pressurized water
streams) and ultrasonic using piezoelectric transducers (in the MHz region as
shown
in Figure 18). Pneumatic dry fog atomizers are generally used for dust
suppression,
industrial/commercial humidification, and medical nebulizers (for inhalation
of
certain medications). Piezoelectric/ultrasonic atomizers are generally used
for
residential/commercial humidification and medical nebulizers. There are many
more
fogger technologies, some of which generating droplets larger than 10 microns
(where
dry fog is not necessary), such as some used for wetting leaves with
pesticides.
1001151 Atomizer source water composition
1001161 Dry fog source water can have different effects depending upon its
composition. For example, as shown in Figure 18, droplet size is smaller when
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surfactants are added (to make soapy water) when compared to distilled water.
Minerals in tap water do not evaporate like water, and the residual can be a
health
concern, and so often distilled water is recommended for use in portable
humidifiers,
especially around children as the minerals are of a size that is easily
deposited in the
lungs. Chemical disinfectants can be added to the source water, such as food-
safe
grades of H202 ("Hydrogen peroxide, well known as an ingredient in
disinfectant
products, is now also approved for controlling microbial pests on crops
growing
indoors and outdoors, and on certain crops after harvest. ... Agricultural
pesticide
products usually contain no more than 35% hydrogen peroxide, which is then
usually
diluted to 1% or less when applied as a spray or a liquid", Hydrogen
peroxide(Hydrogen dioxide)(000595) Fact Sheet (EPA)), to provide additional
germicidal action through radicals. Deionized water has high resistivity,
making it
appear to be a better option for use around electronic components, however, it
is also
known to be corrosive to certain materials. Some non-obvious properties of tap
water
and deionized water are cited below.
1001171 Tap water - "For tap water, the peak diameters of the mist droplets
were
in a larger range with much higher number concentrations compared with pure
water.
Because tap water contains inorganic salts, ion-induced nucleation occurs,
increasing
the number concentrations of nanosized mist. Shimokawa et al. reported that
ultrasonic mist generated from high-purity water has a negative charge [16],
whereas
the mist generated from low-purity water, such as tap water, has no charge.
Therefore, the mist does not grow via mist droplets coalescing because of the
electric
repulsion between the negatively charged droplets, and the mist becomes stable
according to the degree of super saturation. However, for tap water, the mist
droplets
collide and coalesce because the mist droplets generated from tap water have
no
charge. This explains why tap water had two peaks in the size distribution of
the
smaller range." (Kudo, et al. Effect of ultrasonic frequency on size
distributions of
nanosized mist generated by ultrasonic atomization, Ultrasonics sonochemistry
37
(2017): 16-22.)
1001181 "This study investigated the spatial distributions, concentrations,
and
metal and mineral composition of aerosols emitted when an ultrasonic
humidifier
was filled with deionized water (DI), low mineral tap water (LL), high total
dissolved
solids (TDS)/high hardness water (HH), and high TDS/low hardness water (HL).
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indoor air tig/m3 concentrations for particles emitted from ultrasonic
humidifiers
filled with tap water containing minerals exceed ambient air concentrations
for
PM2.5 and/ or PM10. When inhaled during an 8-hr exposure time, and depending
on
mineral water quality, humidifier aerosols can deposit up to 100 s of ps
minerals in
the human child respiratory tract and 3-4.5 times more 1..tg of minerals in
human
adult respiratory tract. Water quality has the greatest impact on the size and
concentration distribution of emitted particulates from an ultrasonic
humidifier.
Water with higher total dissolved solids produced more and larger particles
from
ultrasonic humidifiers than waters with lower TDS. The HL water produced had
more TDS than the HH water, hence why it produced larger and more particles.
Distance in the plume from point of emission has a minor effect and only
results in a
significant difference in particle concentration distributions closer to the
humidifier
outlet in the plume, while particle distributions in the plume and about a
meter below
the plume were the same. Higher TDS results in greater lung dose of particles,
especially for children. Distilled water should be used whenever possible to
prevent
respiratory irritation ..." Fig. 2. shows the "Particle size distribution for
each water
quality at 0.3 m in plume and above floor, 1.5 m in plume and above floor, and
mean
values across all sampling locations in plume and above floor." The highest
mineral
particle concentration is shown to be just under 4E5/cm' (0.3m in the plume)
for
particles 400 nm and smaller. (Yao, et al., Human exposure to particles at the
air-
water interface: Influence of water quality on indoor air quality from use of
ultrasonic humidifiers, Environment International 143 (2020): 105902.)
1001191 "Fine particulates and aerosols emitted by commonly used, room-sized
ultrasonic humidifiers may pose adverse health effects to children and adults.
The
literature documents adverse effects for children exposed to minerals emitted
from
humidifiers. This study performs novel and comprehensive characterization of
bivariate particle size and element concentrations of emitted airborne
aerosols and
particles from ultrasonic humidifiers filled with tap water, including size
distribution
from 0.014 to 10 mm by scanning mobility particle sizer and AeroTrak;
corresponding
metal and elemental concentrations as a function of particle size by
inductively
coupled plasma mass spectrometer; and calculations of deposition fraction in
human
lungs for age-specific groups using the multi-path particle dosimetry model
(MPPD).
Deposition fraction is the ratio of mass deposited to total mass inhaled. When
filled
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with tap water, water evaporated from emitted aerosols to form submicron
particles
that became essentially "dried tap water" with median size 146 nm and mean
concentration of 211 gg-total elements/m3-air including 35 gg-calcium/m3-air
in a
room of 33.5 m3 and air exchange rate at ¨0.8 hr. Approximately 90% of emitted
5 particles deposited in human lungs were <1 pm as shown by MPPD model. The
smaller particles contained little water and higher concentration of minerals,
while
larger particles of >1 pm consisted of lower elemental concentrations and more
water
due to low evaporation. ... A commercially available portable ultrasonic
humidifier
with water consumption rate at 0.21 L/h and run time of about 14 h was placed
at the
10 corner of an unoccupied dorm room on a stand of 0.9 m height, and
maximum output
setting was chosen to represent high-humidity scenario. ... [test instruments]
were
placed 1.5 m away from humidifier outlet in the path of the emitted
aerosols/particles
... The particles reached "steady-state" in the room after 2 h' operation as
the size
distribution of emitted particles did not change significantly after 2 h and
at 8 h (Fig.
15 2). Particle number concentration and mass concentration were constant
approximately at 56,500 particles/cm3 and 320 pg/m3, reported by SMPS. . SMPS
measures submicron particles (0.014-0.750 mm), AeroTrak measures larger
particles
(1-10 gm), and the impactor collects particles in 5 size bins (<0.25 gm, 0.25-
0.50 gm,
0.50-1 pm, 1-2.5 pm, >2.5 gm). The particle sizers take measurements every 6
min
20 during the 8-h humidifier operation. ... At steady-state, indicated by
the 8th hour
data, 95% of particles fell into the size range of 51-424 nm. Large particles
of size 1
gm, 2.5 gm, 5 gm, and 10 pm were measured by the AeroTrak and had
significantly
lower concentrations than the 0.014-0.750 pm particles measured by SMPS." An
overlooked route of inhalation exposure to tap water constituents for children
and
25 adults - Aerosolized aqueous minerals from ultrasonic humidifiers.
1001201 Deionized (DI) water - An advantage to DI water is that conductivity
can
be lowered to a level such that electrical-shorts and the like can be avoided.
However, DI water can lead to corrosion, although to minimize this,
surfactants (e.g.,
food safe and/or non-ionic) can be added. Corrosion can also be limiting by
raising
30 the pH, which is shown in Potential-pH or Pourbaix diagrams (Principles
of
Corrosion Engineering and Corrosion Control, ISBN 0750659246), and in addition
by removing carbonates as shown in the 'Baylis Curve' (Causes of Corrosion) in
order to also prevent scale forming. CO2 is also a source of corrosion
problems, as it
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"dissolves in any water present to form carbonic acid 1-12CO3." (Effect of
demineralized water on carbon steel and stainless steel). Thus, the
removal/avoidance
of CO2 will also help avoid/minimize con=osi on. For example, bulk water for
use in
dry fogging can be shipped in containers that fill air space with nitrogen.
Similarly,
CO2 can be excluded/minimized from inside a UVC tunnel via scrubbers and/or
displacing with a positive pressure of nitrogen, noble gas or other.
1001211 Dry fog Atomizers/Nebulizers
10012211 a) Dry fog characteristics - Note that many (not all) technical
references
tend to relate 'dry fog' to droplet diameters of 10.t and less and/or provide
a
qualitative description. In Humidification and ventilation management in
textile
industry (ISBN 978-81-908001-2- 9), it states: "small droplets rebound from an
object, but large droplets get burst and wet the object. This is just like how
soap
bubbles do. That is why the dry fog does not wet the object ... Dry fog
condition:
Maximum droplet diameter 50 or less and mean droplet diameter 10p.. or less."
1001231 A more analytic approach is discussed, e.g., in Fine Sprays for
Disinfection within Healthcare, citing Development of Methodology for Spray
impingement Simulation in fact, the first reference cites a Sauter Mean
Diameter
(SMD) of between 10 and 25 microns that 'is not "wet" (SMD and other particle
measurement standards are defined in The Mechanics of Inhaled Pharmaceutical
Aerosols - An Introduction, ISBN 0-12-256971-7). The references describe the
characteristic phenomena of droplet impingement on surfaces, also citing
critical
'Weber numbers' to determine rebounding and attaching and splashing on a
wetted
surface "a droplet which hits the wall is assumed to suffer one of the two
consequences: namely rebound or breakup, depending on the impact energy. The
transition criterion between these two regimes is described by a critical
Weber
number". Knowledge of the factors that go into wetting is of use in the
instant
invention for optimizing parameters in a given application, especially for dry
foods
where wetting is undesirable. Note below Tw= 'wall temperature', TpA='pure
adhesion temperature' below which adhesion occurs at low impact energy;
TpR=`pure
rebound temperature', above which bounce occurs at low impact energy. Notice
that a
'dry wall' is distinguished from a 'wetted wall', and so for the instant
invention, the
calculations and parameter adjustments must accommodate this difference. In
one
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embodiment, the surface is a 'dry wall' (a loaf of bread being disinfected),
and the
intent is to keep it dry.
[00124] "1. 'Stick'- in which the impinging droplet adheres to the wall in
nearly
spherical form. This occurs when the impact energy is very low and the wall
temperature Tw is below a characteristic temperature, TPA, which will be
defined
shortly.
[00125] 2. 'Spread'- where the droplet impacts with a moderate velocity onto a
dry
or wetted wall and spreads out to form a wall film for a dry wall, or merges
with the
pre-existing liquid film for a wetted wall.
1001261 3. 'Rebound'- in which the impinging droplet bounces off the wall
after
impact. This regime is observed for two cases: (i) on a dry wall when Tw >
TPR,
another characteristic temperature to be defined later, in which case contact
between
the liquid droplet and the hot surface is prevented by the intervening vapor
film; (ii)
on a wetted wall, when the impact energy is low, and the air film trapped
between the
droplet and the liquid film causes low energy loss and results in bouncing.
[00127] 4. 'Rebound with break-up'- where the droplet bounces off a hot
surface
(Tw < TpR), accompanied by breakup into two or three droplets
[00128] 5. 'Boiling-induced breakup'- in which the droplet, even at very low
collision energy, disintegrates due to rapid liquid boiling on a hot wall
whose
temperature lies near the Nakayama temperature TN.
[00129] 6. 'Break-up'- where the droplet first undergoes a large deformation
to
form a radial film on the 'hot' surface (Tw > TPA), then the thermo-induced
instability
within the film causes the fragmentation of the liquid film in a random
manner.
1001301 7. 'Splash'- in which, following the collision of a droplet with a
surface at
a very high impact energy, a crown is formed, jets develop on the periphery of
the
crown and the jets become unstable and break up into many fragments."
[00131] The second reference goes on to cite the parameter space for
determining
the type of impingement: "The existence of these impingement regimes is
governed
by a number of parameters characterising the impingement conditions. These
include
incident droplet velocity, size, temperature, incidence angle, fluid
properties such as
viscosity, surface tension; wall temperature, surface roughness, and, if
present, wall
film thickness and gas boundary layer characteristics in the near-wall
region."
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1001321 With respect to the incidence angle, see Impaction of spray droplets
on
leaves- influence of formulation and leaf character on shatter, bounce and
adhesion
(2015), citing/interpreting Spread and Rebound of Liquid Droplets upon Impact
on
Flat Surfaces, the former stating, "Mundo et al. (1995), who proposed the
relation K =
Wen1/2Reõ1/4 ; (1) where We, = pV,2D/a and Re .= pV,D4t are the dimensionless
Weber and Reynolds numbers computed with the component of velocity normal to
the
impacted surface V, = (V sin a) ; (2) Here a is the angle between the leaf
surface and
the incoming trajectory of impact (0 < a < 90.). Thus (1) is valid for both
normal and
oblique impactions. A droplet is predicted to shatter on impact if K > Kar,
(3) where
Kc,, is a critical value related to the properties of the surface being
impacted. ... Note
that as the angle of impact a decreases, V, will in turn decrease, leading to
a smaller
calculated value of K. The implication of this trend is that shatter becomes
less likely
with a smaller impact angle. ... Note that as the angle of impact a decreases,
V, will
in turn decrease, leading to a smaller calculated value of K. The implication
of this
trend is that shatter becomes less likely with a smaller impact angle. ... A
successful
bounce is indicated by a positive value of an 'excess rebound energy': FERE >
0. If
FERE < 0, then the droplet is predicted to adhere to the substrate ", where
FERE =
[(R/4) Dmajor2 (1 - cos 0) + (2/3)it(D3/Dmajor)]O
- 0.12702a (Dmajor /1:3)23 (1 - COS 00 63 - naD2 , and D =droplet diameter
before
impact, Dmajor =major diameter of the resultant elliptical droplet formed at
the surface
during impact, a =surface tension of the droplet, and Oe the equilibrium
contact angle.
The value of Dmajor is determined by solving two cubic equations, numbers (5)
and (7)
as defined in the paper (including the calculation of Dnormal in order to
calculate Dminor,
then finally Dmajor), and then the 'excess rebound energy' is calculated to
determine if
the droplet striking a surface at an oblique angle bounces or adheres. Note
that Dmaliof
is dependent on e, the Weber and Reynolds numbers, (We, Re) using the normal
velocity, V,. Laboratory measurements are presented for water (and other
liquids with
different surface tensions) at normal incidence and at 45 degrees, both on
wheat and
cotton leaves. The authors acknowledge scatter in the test results, owing to a
number
of factors, e.g., the complexity of using real leaves, non-monodisperse
droplets,
surfaces are not always dry, etc. Nonetheless, this information establishes a
good
baseline of the factors influencing wetting for the instant invention, and
test
procedures, both in the paper and in the references.
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001331 A dry-fog can extend beyond 10t.t diameter droplets when considering
the
wide range of free variables described above. Note, however, that the
application cited
in the above required some amount of adhesion of the droplet to the wall,
since
chemical contact was required, which is not a basic requirement for the
certain
embodiments in the instant invention.
1001341 From a practical perspective, each application of the instant
invention will
occupy a parameter space (with spatial and temporal variations), e.g., on
number
concentration layer thickness, and droplet sizes that provide desirable
scattering
profile, as well as bounds on the allowable amount wetting (which may be 0 or
close
to 0 for some applications, and larger for others, e.g., in greenhouses where
the fog
can also be used to hydrate the plants) which is a function not only of
droplet sizes,
but as disclosed herein, many other parameters as well. In addition, there are
other
considerations, e.g., (a) the effect of irradiation as a function of moisture
content
and/or wetness of the product(s) being irradiated (see, e.g., Optimization of
UV
irradiation conditions for the vitamin D2- fortified shiitake mushroom
(Lentinula
edodes) using response surface methodology and Inactivation of Listeria and E.
coli
by Deep-I.TV LED - effect of substrate conditions on inactivation kinetics),
(h) the
degree to which the processing equipment (e.g., UVC tunnel) and/or ancillary
equipment (e.g., hospital EKG machine next to a patient's bed to be
disinfected with
UVC dry fog scattering, or greenhouse ventilation fans in a room with
Visible/NIR
dry fog scattering, etc.) in/near the treatment area can handle wetness over
time (e.g.,
re: corrosion), (c) whether there is a drying process step after any wetting
imparted
during the dry fog scattering of UV (or Visible/NIR, etc.), (d) whether a
small number
concentration of 'wet' droplet diameters can be accommodated due to the
tradeoffs
when choosing an atomization approach (see, e.g., the distributions in Fig.
4.23 in
Humidification and ventilation management in textile industry), (e) whether
the large
droplets impinge on a surface and break up and/or work to increase the
humidity in
support of minimizing evaporation of the sub-10p. droplets, (f) whether a
demister/separator is used to remove certain droplet sizes, etc.
1001351 So, the efficacy of the instant invention, inter alia, requires a fog
whose
degree of dryness is based on the management of droplet sizes to balance
scattering
vs. wetness.
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001361 One then can characterize the dry fog as comprising a droplet
distribution
based on diameter, volume, mass, etc., (where the distribution can be
monodispersed
or polydispersed) of a range of thicknesses meeting predefined light
scattering
(relative to one or more wavelengths) and wetness criteria (with or without
any
5 wetting, the latter true, e.g., of a 3.611 diameter monodispersed
concentration of water
droplets).
1001371 These dry fogs can further be characterized as produced by one or more
artificial atomizers, such as one or more of the types cited herein, e.g.,
pneumatic, or
piezoelectric/ultrasonic (as opposed to a natural fog due to weather
conditions), where
10 a collection of atomizers can be of the same type or a mixture of types.
[00138] Piezoelectric Ultrasonic atomizers ¨ these use high frequency (often
MHz,
sometimes kHz) electrical excitation to deflect a transducer causing ejection
of
droplets, and can be found in a wide variety of applications, including those
that are
generally enclosed and packaged as medical nebulizers, theatrical fog effects,
15 residential/commercial/industrial humidification, etc. Specialty 'mesh'
type ultrasonic
transducers can be found in the I-neb Adaptive Aerosol Delivery (AAD) System
from
Philips Respironics (Murrysville, PA) Simpler devices are available in single
transducer kit form, e.g., from Best Modules Corp. (Science Park, Hsinchu,
Taiwan)
as used herein to evaluate the particle number concentration using three of
their 10
20 watt transducers. It was found that for this configuration, in a closely
packed
triangular array, a 635nm laser beam could not visually traverse the fog
blanket they
created in an ¨ 8"x10" container, suggesting these devices are suitable for
use in the
instant invention, as the fog field can be easily diluted to get a wide range
of forward
scattering distributions. Multi-element transducer modules are available,
e.g., from
25 The House of Hydro (Fort Myers, Fl). These types of arrays can be found,
e.g., in
turnkey products such as that detailed in Ultrasonic Humidifier System -
Jiangsu
Shimei Electric Manufacturing Co. This shows a fan blowing air into the unit,
around
a baffle, and then directs the dry fog generated from an array of ultrasonic
atomizers
(e.g., each operating at 1.7 MHz, submerged under water) out of the unit
through one
30 or more exit holes (higher wattage systems have more than one hole) that
are
constructed to receive a specific diameter PVC pipes. The dry fog exiting the
PVC
pipes can be directed into a UV tunnel from the entrance and/or exit sides, or
into a
manifold with a plurality of ports to distribute the dry fog over a target
area. This fog
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delivery approach can be seen as a fog injector, or simply an injector that
injects the
fog between the UV source and the target surfaces, including those in shadow.
In one
preferred embodiment, the dry fog is directed at the top surface of a conveyor
belt,
forming a layer thickness/distribution that is optimized for a given object.
Note that
the transducers are submerged in the source water with a preferred amount of
water
column above them. In one embodiment, baffles are added in the source water to
minimize sloshing that would vary the height of the water column. Note also
that
these transducers each create a small fountain at the water surface. If this
is impeded
(as was found in the inventor's own early testing), the fog will not generate
or will be
suppressed.
[00139] The ultrasonic systems using the trade name 'humiSonic' from Carel
(see
Figures 32 ¨ 38) are described in technical detail herein. These systems in a
sense are
more sophisticated due to their extensive network interface and onboard
computerized
control system.
[00140] As an aside, also recall the use of dry fog in a greenhouse for
scattering (a)
visible/MR light to promote photosynthetic plant, and/or (b) UVC/B/A light to
curtail
bacterial/viral/fungal growth on plants In these instances, the dry fog can be
applied
via stationary foggers with PVC pipe routing as needed and/or via mobile
foggers,
with the appropriate light source(s) fixed and/or mobile as desired for the
application.
[00141] To accurately model scattering using optical ray tracing, it is
beneficial to
obtain droplet size distributions. This is shown for piezo-type ultrasonic
transducers
using both pure water and tap water in Effect of ultrasonic frequency on size
distributions of nanosized mist generated by ultrasonic atomization. The y-
axis can be
understood by reading Aerosol Statistics Lognormal Distributions And dN
dlogDP,
which includes the explanation that the y-axis is not simply the number
concentration,
N, because of how differing binning can make similar data look different. This
is
useful to understand as some data is only provided in this format. See also
section '1.1
Size Distribution' of Some Useful Formulae for Aerosol Size Distributions and
Optical Properties. Note that tap water has mineral content, and while water
evaporates, minerals do not.
[00142] See Figure 18 for plots of fog droplet sizes based on frequency for
distilled
and hi/lo soapy water surface tensions (droplet sizes decreased using
surfactants in
comparison to distilled water). See also Fig. 5b in Size distributions of
droplets
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produced by ultrasonic nebulizers re: a droplet size distribution for a 1.7
MHz
ultrasonic (piezoelectric) 'Mist maker' atomizer, normalized to the median
size, <d>,
of 5.6 t.tm
1001431 The water layer thickness above the piezo element also has an effect
on
overall performance and is typically specified 3.0-4.5cm and may be affected
by the
radius of curvature for focused transducers. "In the simplest design, the
liquid to be
nebulized comes into contact with a flat transducer, oscillating at the
desired
frequency. In this arrangement the energy is termed unfocused. The arrangement
allows all of the liquid to eventually be aerosolized from the surface without
much
change in the aerosol characteristics. A second design curves the transducer
to
produce a focused point of energy in much the same fashion as a concave mirror
focuses light at a single point. This arrangement is capable of producing a
finer
aerosol; however, as the liquid level drops in the nebulizer cup, the surface
of the fluid
moves below the focal point and the efficiency of the device decreases.
Ultrasonic
nebulizers with focused transducers require a separate continuous-feed
mechanism to
maintain the liquid level at the appropriate height above the transducer. The
sonic
energy decreases with increasing distance from the focal point (1/3) Devices
employing flat transducers are preferred for administration of small volumes
of drug
(13). In some devices, the solution to be nebulized comes into direct contact
with the
transducer or a bonded surface above the transducer. In others, a liquid
interface acts
as a couplant between the transducer and the base of the nebulizer cup. This
couplant,
usually water (for safety reasons), allows the base of the nebulizer cup to be
shaped
for more efficient transfer and focusing of the energy." Chapter 10,
'Ultrasonic and
Electrohydrodynamic Methods for Aerosol Generation', Inhalation Aerosols -
Physical and Biological Basis for Therapy, Second Edition ISBN 978-0-8493-4160-
1.
Note that this textbook contains a wealth of information on all aspects of
droplet
formulation, evaporation, coagulation, etc. A Third Edition is available, ISBN
978-1-
1380-6479-9, with additional content. See also US8001962 Nebulizing and drug
delivery device and US9339836 Ultrasonic atomization apparatus.
1001441 Sophisticated complete ultrasonic humidifier systems are available
from
Card l humi Sonic (Card l Industries S.p.A., Padova, Italy), including serial
communications for control, monitoring, and networking more than one unit.
Salient
details are provided in Figures 32-38. In one embodiment, an array of Carel
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humiSonic compact ultrasonic dry fog humidifiers (Carel Industries S.p.A.,
Padova,
Italy) is aligned along the length of a UV Tunnel, with a hose from each unit
directing
fog within the tunnel (individual units up to 1 kg/h humidified air at 110
watts).
Operational and system-level details are provided in Carel humiSonic Compact
Manual comprising a single output port, although the manual shows how to
connect
to a manifold distributor with multiple ports. Details are provided in Figures
36-38.
These systems periodically drain to provide a washing function to minimize
scale
build-up, flush residual dirt, and remove stale water to avoid hazardous
microbial
growth. An RS-485 serial link provides communication to/from the unit. The
system
can be configured for proportional control using an external signal. See also
Carel
humiSonic Direct User Manual (up to 8 kg/h humidified air at 690 watts)
comprising
multiple output ports, parts of which are replicated in Figures 32-35. These
manuals
provide a wealth of detailed information, including RS-485 command structure
for
system parameters (referenced below) that can be exchanged over the link.
RS485
controllers can be purchased, e.g., from the industrial automation group of
Siemens
(Nuremberg, Germany and Alpharetta, GA), which includes their SIMATIC line of
controllers as well as from NI (formerly National Instniments Corporation,
Austin,
TX), which includes their Lab VIEW graphical programming language suitable for
use
with their industrial controllers.
1001451 Figure 32 shows an isometric picture and exploded view of the Carel
humiSonic ultrasonic humidifier. Part numbers are shown in Figure 34. Note the
diffusers, 4 and 5, for directing the flow as required. Note the fan, 7, that
is used to
push out the atomized air created by the ultrasonic transducer, 11, from its
section of
the fog chamber into its four respective diffusers. The unit comprises a fill
solenoid,
10, a drain solenoid, 9, and a level sensor, 13 that feeds into the control
system.
Figure 33 shows the operating principals of the atomizer, including 1.7 MHz
ultrasonic transducers, 12, operating on water in a tank, 10, with an
atomization
chamber, 5, assisted by a rear fan, 2, for pushing out the atomized air, and a
front fan,
14, providing laminar air flow adjacent to the atomized water, 3, exiting the
unit.
Figure 34 identifies the basic parameters of the system, including units of
measure
(UoM), the parameter range, the default values (clef), and notes. Figure 35
describes
service parameters in a similar way. These parameters are communicated to
other
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units and a system controller via serial communication links. See the manual
for more
details.
[00146] Figure 36 shows the 'Compact' or modular ultrasonic humidifier from
Carel, with part numbers shown in Figure 38. The unit can be fitted with one
or two
ultrasonic transducers. As shown in Figure 36, the unit can be fitted with a
hose and
manifold distribution system. The structure is similar to a single section of
the larger
unit shown in Figures 32-35, and thus will not be repeated. Figure 37 details
requirements relative to hose size and length, as well as maintaining a 20
gradient
(relative to the water line) for proper condensate drainage (either back to
the unit for
recycling, or to an external drain). A diffuser accessory is shown for
configurations
where a manifold is not suitable. A NOTICE is provided to avoid pressure-
related
flow issues or creating a goose-neck section in the hose that could lead to
siphoning
(or a water trap from condensate that can clog the flow over time). The
parameters are
similar to that in Figures 34 and 35, so they will not be repeated. Figure 38
shows the
alarms (similar to that of the larger unit in Figure 32), e.g., related to no-
water,
high/low humidity, water-level, self-test, transducer end of life (9,999 hours
using
deminerali zed water per the note in Figure35), etc. Alarm notifications
activate an
LED indicator and energize relays for immediate control.
[00147] =Note that the Carel documentation does not specify Nd, and thus
testing is
required to understand the number of ultrasonic transducers are required for a
given
scattering application.
[00148] In a preferred embodiment, additional commands and alarms are added to
the suite defined by the Carel humi Sonic product. Examples of commands would
be:
read scatterometer sensor(s), constant/open-loop Nd mode(s), set Nd to a fixed
value in
layer number 'n', read internal wind velocity, read external wind velocity,
read UV
intensity source monitor sensor(s), read UV intensity at target location(s),
tent/tunnel
speed relative to the ground, set fan/blower speed for controlling Nd of
injected fog.
etc. Examples of alarms would be: unable to reach Nd, UV lamp failure(s), lamp
temperature exceeded, etc.
[00149] Note also that the HEART nebulizer used for measurements herein
receives power from an air compressor rated at 495 watts, which cycled on/off
during
testing roughly 60 seconds-on and 30 seconds-off, or a duty cycle of
60/(60+30)=67%. The average power is then roughly 67%*495 watts = 331 watts.
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This nebulizer, according to the datasheet, has a "High aerosol output (up to
50
mL/hr)". Note that 1 liter of water weighs 1 kg, so 50mL is equivalent to
(50/1000)=.05 kg of humidified air. To (very) rough order, the efficacy of
this
approach is therefore .05 kg/hr @ 331 watts = 1.51E-4 kg/hr-watt. The Care!
Compact
5 unit outputs 1 kg/hr @ 110 watts for an efficacy of 9.09E-3kg/hr-watt,
and the larger
Carel unit outputs 8 kg/hr @ 690 watts for an efficacy of 1.15E-2kg/hr-watt.
Note that
an hr-watt (or watt hour) is a joule. So, the HEART outputs 1.51E-4 kg/J, and
the
Carel units output 9.09E-3 kg/J and 1.15E-2 kg/J, respectively. Therefore, the
ultrasonic based Carel units are 9.09E-3/1.51E-4=60 and 1.15E-2/1.51E-4=76
times
10 higher in efficacy than the pneumatic HEART nebulizer (assuming all else
is roughly
equal, like the particle size distributions, and that the compressor that was
used has
reasonable efficiency).
1001501 Pneumatic atomizers ¨ there are two main groups that use impingement
of
water to create dry fog droplets. One type uses compressed air impingement on
still
15 water, e.g., used in a medical nebulizer cup such as the HEART
nebulizer used for
testing herein. Another uses one of a variety of impingement nozzles that use
one or
more of a pressurized air stream against, a pressurized water stream, and a
specially
fabricated impingement surface. A HART Environmental nozzle using pressurized
air
and water streams was evaluated for the instant invention. These are used in
dust
20 suppression, commercial/industrial humidification, and even aircraft
environmental
testing as will be disclosed below.
1001511 i) Nebulizers of the type typically used for drug delivery are, e.g.,
the B&B
HOPE NEBULIZERTM from B&B Medical Technologies (Carlsbad, CA) and
HEART nebulizers from Westmed, Inc. (Tucson, AZ). These devices tend to be
25 designed to eliminate particles large enough to cause wetting,
generating particles
small enough to ensure they make it into the lungs. The HEART nebulizer
specifies
`2-311 particles' and is rated at aerosol flow rates 'up to 50 mL/hr' which is
equivalent
to .0083 liters/min (LPM). The instructions state to set an airflow flowmeter
to a flow
rate of 15 liter/minute at 50 psi into the nebulizer and the output flow rate
will be 50
30 ml/min ( 20%). Note that the water resides in the integral container,
and no external
source of water pressure is needed. For insight into the number concentration
available from nebulizers, see, e.g., Dynamics of aerosol size during
inhalation -
Hygroscopic growth of commercial nebulizer formulations, and Characterization
of
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aerosol output from various nebu I zer compressor combinations. The first
reference
contains a chart citing the number concentrations for various commercially
available
nebulizer/compressor combinations, i.e., pneumatic nebulizers.
1001521 ii) Nozzles traditionally used for dust suppression, e.g., Dust
Solutions,
Inc. (Beaufort, SC), Hart Environmental, Inc. (Cumming, GA), and for control
of
humidity, applying chemicals, disinfection, cooling, and static control, are
available
e.g., from Sealpump Engineering Limited (Redcar, England), Koolfog, (Thousand
Palms, CA), and Ikeuchi USA, Inc. (Blue Ash, OH).
1001531 The Sealpump Engineering 035H Ultrasonic Spray Nozzle specifies at 5
bar air (72 psi) and 0.5 bar liquid (7.2 psi) it is rated at 1.2 liters per
hour, or 0.02
LPM - roughly 2.4 times the output of the HEART nebulizer, although the
droplet
size distributions of both are not published by the manufacturers. The 03511
droplet
size is stated as '3 ¨ 5 micron droplets'. Note the term 'ultrasonic' in this
context is
described on the Sealpump Engineering site as follows: "Ultrasonic fogging
nozzles
are twin fluid type spray nozzles, usually using compressed air and water to
create a
finely atomised water droplet, typically this nozzle range produces droplets
from 3 to
10 micron This ultra-fine droplet is created through its unique nozzle design
compressed air passes through the nozzle at high velocities and expands into a
resonator cavity where it is reflected back to complement and amplify the
primary
shock wave. The result is an intensified field of sonic energy focused between
the
nozzle body and the resonator cap. Any liquid capable of being pumped into the
shockwave is vigorously sheered into fine droplets by the acoustic field. The
droplets
have low mass and low forward velocity with low impingement characteristics.
Fine
atomisation ensures uniform distribution of the liquid with minimum of
overspray and
waste." See also Sealpump Spray Technology for the Food & Bakery Industries,
describing 'Ultra-fine fogs down to only 1 micron (0.001mm)' for the bakery
industry, where 'systems can be supplied with humidity sensors and full
control
package'.
1001541 This type of dry fog nozzle is marketed, e.g., for dust suppression.
See also
Dust Solutions, Inc. (Beaufort, SC) and JD UltraSonics - Product and
Information
Catalogue (also includes system connection diagrams and associated
components).
The nozzles are inserted into a nozzle adapter that routes the air and water
to the
appropriate inlets.
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1001551 Additional details of the 035H and similar nozzles can be found in
Spray
Nozzle Designs for Agricultural Aviation Applications, Nozzle Type Evaporative
Cooling System in the Greenhouse, Using Agglomerative Dust Suppression and
Wind
Breaks for Fugitive Dust Abatement, Dust Control Handbook for Industrial
Minerals
Mining and Processing, as well as Micron Droplet Dust Suppression Proves Out
in
Variety of Fugitive Dust Applications (5th Symposium on Fugitive Emissions -
Measurement and Control).
1001561 The design (including CFD analyses) and use of a venturi fitted on the
output of such a nozzle to direct the spray pattern is discussed in Design and
field
trials of water-mist based venturi systems for dust mitigation on longwall
faces. Such
an approach would be useful for directing fog in outdoor applications such as
farms
and vineyards.
1001571 Pressurized water for an 035H nozzle can be derived via regulating
municipal water, or by using a pressure pot like those used in spray painting -
just use
water instead of paint, where the compressed air feeding the pressure pot will
force
water out of the pressure pot under pressure, which can then be fed through a
pressure
regulator. Pressure pots are available from, e g , TCP Global (San Diego, CA)
Note
that water-siphoning can occur once the compressed air is removed, and so a
shutoff
(or anti-siphon) valve on the water supply may be needed to avoid water
streaming/dripping from the nozzle for those applications that are sensitive
to water
(like bread during UVC exposure).
1001581 The requirements for dust suppression allow for larger particle
diameters
than medical nebulizers. Removal of larger particle sizes (to ensure a level
of fog
'dryness' suitable for the application requires demisting (via mist
eliminators) as
previously cited. A good summary, can also be found in AMACS Mist Eliminator
Brochure, stating in part "Mechanisms of Droplet Removal - Droplets are
removed
from a vapor stream through a series of three stages: collision & adherence to
a target,
coalescence into larger droplets, and drainage from the impingement element.
Knowing the size distributions ... is important because empirical evidence
shows that
the target size - important in the first step of removal - must be in the
order of
magnitude as the particles to be removed." See also the mist elimination
technologies/products in the Koch-Otto York Product Catalog.
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1001591 Droplet diameter distribution data was obtained from Dust Solutions,
Inc.,
Beaufort, SC), based on internal laser diffraction testing of an -052 type
nozzle (P/N
DSN-3) showed the median droplet size of 1-31.t and almost nothing greater
than 45p.
1001601 Qualitative testing for the instant invention was performed on a 035H
nozzle from Hart Environmental Inc. (Cumming, GA). Compressed air was
generated
in on/off cycles by a 490 watt compressor (0.6 HP Rated/Running, 1.2 HP Peak,
1.60
CFM @ 40 PSI, 1.20 CFM @ 90 PSI) with an integral 1 gallon tank, P/N 1P1060SP
from California Air Tools (San Diego, CA), passed through a secondary 3 gallon
storage tank, routed through a pressure regulator, and was connected to the
air-port of
the nozzle. Instead of using a pressure regulator connected to a pressurized
domestic
water source (e.g., city water or pumped well water), the same compressed air
was
connected to a pressure regulator fitted to a 2 liter VEVOR Pressure Pot Tank
purchased via Amazon and filled with tap water, where the pressurized water
output
was connected to the liquid port of the nozzle. This allows a greater range of
pressures, including negative pressures by shutting air pressure to the
pressure pot,
and allowing the nozzle to suck water from the pot via the air connection to
the
nozzle. The air and water pressures were varied per the manufacturer's
instnictions
and monitored via pressure gauges.
1001611 The fog dispersal patterns and apparent 'dryness' were qualitatively
evaluated. The dispersal pattern was sensitive to pressure changes. The volume
of fog
was significantly more than the HEART nebulizer, but the fog was also much
wetter
when a hand is placed in front of the nozzle when compared to the HEART
nebulizer (or when a hand is dipped into the piezoelectric ultrasonic fog
field). Note
that the manufacturer cautioned that placing a hand in front of the spray will
cause
impingement and thus larger droplets.
1001621 At 48 psi air, and with about 10 psi water, the spray tends to focus
and is
relatively uniform, but it was wetter than the output of the HEART nebulizer.
Then
by lowering the water pressure, the spray seemed dryer, but the spray appeared
to be
lower in volume, and also started to exhibit wider lobes. Per the
manufacturer, the
maximum droplet size can be seen at 62 psi air and 20 psi water, with smaller
droplet
sizes achieved using 47 psi air and 0 psi water, where the water is drawn from
the
pressure pot, through the hose connected to the nozzle's water port, via the
air that
flows through the nozzle. The smallest droplet sizes are said to be generated
at 44 psi
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air and -2 psi water. A piece of open cell foam was used to filter out the
larger
droplets via impingement. A dry fog similar to the output of the HEART
nebulizer
was visible on the output side of the open celled foam. Note that disclosed
previously
herein are additional methods for separating larger droplets from smaller
ones.
1001631 For use in the instant invention, in an exemplary embodiment, a 'spray
bar' would be mounted inside a UVC tunnel. For applications where 'dryness' is
extremely important (e.g., UVC irradiation of bread), larger droplets are
removed via
impingement (or other method as cited in these patent filings) with the water
collected
and routed to a drain or back to the supply source for recycling. For
applications
where some wetness is not a concern (e.g., UVC irradiation of fish fillets, or
visible/NlR irradiation of plants in a greenhouse), the large droplet removal
feature
may be unnecessary if testing proves the scattering/system efficacy is
sufficient to
achieve the log reductions (UVC) or photosynthetic growth (visible/N1R)
1001641 Dry fog characteristics - Dry fog droplets can evaporate quickly as
disclosed in Figure 19. On the left hand side of Fig. 19, there are two charts
modeled
after Equation 3 in the cited reference. The model for the equation assumes no
evaporation at 100% humidity. The upper chart represents the evaporation time
or a
water droplet at rest from the specified initial diameter to 75% of that, for
diameters
of 1p, 21.1, 5p, and 10 respectively at various relative humidities at 25 C.
The lower
chart is similar except the evaporation time encompasses complete evaporation
(to 0%
of the initial diameter). The chart on the right is based on a different model
that
describes complete evaporation in 100% relative humidity (RH), also at 25 C.
Regardless of the model, the charts imply that increasing RH increases
prolongs the
life of a droplet, and that smaller droplets evaporate more quickly.
1001651 Droplet size modelling is surprisingly complicated as it includes
things
like the following: "...corrections for the Fuchs effect, the Kelvin effect,
and droplet
temperature depression. ... For water droplets less than 501..tm in
aerodynamic
diameter, the evaporation rate is increased less than 10% by the "wind"
velocity
effect.... As with growth by condensation we must take into account the effect
evaporation has on the droplet temperature Td. Here, the droplet is cooled by
the heat
required for evaporation. This cooling lowers the partial pressure of vapor at
the
droplet surface, pd and the rate of evaporation, d(dpd)/dt. . . Although
relative
humidity can affect droplet lifetimes by a factor of 10-1000, ambient
temperature has
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a much smaller effect, as shown by the dashed lines for 10 and 30 C in Fig. 13
lla."
(Ch. 13 Condensation and Evaporation. Aerosol Technology: Properties,
Behavior,
and Measurement of Airborne Particles, 2nd Edition, William C. Hinds, ISBN:
978-0-
471-19410-1, January 1999).
5 [00166] The management and control of droplets of the sizes in a dry fog
field
involves other factors disclosed in Applicant's ILTVA presentation cited
herein. For
example, dry fog droplet sedimentation or settling due to gravity, is often
said in the
literature to take hours to days, although the rapid evaporation of these
small droplets
is not mentioned. Coalescence (droplets combining) and impaction (droplets
striking
10 something) will change the size distribution, which may also compensate
to some
degree for evaporation and can also lead to larger diameter drops that cause
wetting
and changes to the scattering profile. Demisting can be used to remove larger
droplet
sizes. Considerations including condensation/wetting, films vs. drops, rate
effects as
a function of surface inclination, vapor pressure, impaction/impingement
velocity
15 (speed & direction relative to the impinged surface normal), surface/air
temperature
differences, and non-condensable gases are cited in the presentation.
[00167] When liming dry fog, especially in high RH environments, the effect of
the
sorption of water on/in targets must be considered. In the food industry,
"Water
activity (aw) is a measure of the availability of water for biological
functions and
20 relates to water present in a food in "free" form. ... Water activity of
pure water is
1.0, a completely dehydrated food is 0. ... Water activity requirements of
various
microorganisms vary significantly. In the vital range of growth, decreasing aw
increases the lag phase of growth and decreases the growth rate." Food
Microbiology
- Principles into Practice (ISBN 9781119237761)
25 [00168] The Dust Solutions website states "Dry Fog works very well in
below
freezing conditions. Fog droplets lack sufficient mass to freeze. This
phenomenon is
known as Cloud Physics. The system components can be protected via insulated
enclosures with self-regulating heaters and heat tracing as well as an
automatic purge
system upon system shutdown." See also Fig. 1 from A Laboratory Investigation
Of
30 Droplet Freezing which summarizes pure water droplet freezing
temperatures from a
number of studies, indicating that temperatures below -35 C are required to
freeze dry
fog droplet sizes. See also Exploring an approximation for the homogeneous
freezing
temperature of water droplets. This phenomenon is quite unexpected and not
obvious.
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Thus, for the instant invention, scattering operation extends well below
freezing
temperatures (useful to curb microbial growth), but of course is also
dependent upon,
e.g., number concentration, fog thickness, relative humidity, and temperature
fields in
the treatment zone. It is also known that wetting is dependent upon viscosity.
The
viscosity of supercooled water is provided in Viscosity of deeply supercooled
water
and its coupling to molecular diffusion, Figure 1 in this reference shows that
the
viscosity of water increases from about 0.001Pa-s (N-s/m2) at 25 C (298 K) to
about
0.016Pa-s (N-s/m2) at -34 C (239 K). The density of water is 1 g/mL at 25 C,
and at -
34 C (supercooled) it drops slightly to 0.9975 g/mL as shown in Table II of
The
density of supercooled water. 11. Bulk samples cooled to the homogeneous
nucleation
limit. The surface tension of water is shown in Figure 9 of Surface Tension
of
Supercooled Water - Inflection Point-Free Course down to 250K Confirmed Using
a
Horizontal Capillary Tube, increasing from about .075N/m at 0 C to ¨ 0.079N/m
at -
25 C (248 K). Note that by adding a surfactant to make soapy water, the
surface
tension drops to 0.0250 - 0.0450 at 20 C per the website Engineering ToolBox.
Also,
in Surface tension of supercooled water nanodroplets from computer
simulations,
there is an analysis that looks at the surface tension of curved (ys) vs
planar (yp)
surfaces down into the supercooled region, albeit for nanometer sized
droplets,
"Moreover, assuming the validity of thermodynamic route, for Re? 1 nm we can
ignore the curvature correction and use the planar surface tension to estimate
the
Laplace pressure inside water nanodroplets to within 15% down to 180 K" where
"Rs is the radius of the so-called \surface of tension" [10]. For macroscopic
droplets,
the width of the molecular interface is negligible compared to the droplet
dimensions, and Rs is simply the radius of the droplet. However, for nanoscale
droplets, the interfacial width is significant compared to the size of the
droplet itself,
and various definitions for the radius of the droplet are possible. It has
long been
understood that the surface tension of a curved interface deviates from that
of a
planar interface. For a curved surface, such as that of a droplet, the Tolman
length 8
quantifies how ys deviates from the planar surface tension yp as a function of
Rs, via
the expression [11], ys =yp ( 1 + 28/11s): (2) The magnitude of 8 is generally
found to
be 10-20% of the molecular diameter" and "Re is the radius of a sphere that
has a
uniform density equal to that of the interior part of the droplet and that has
the same
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number of molecules as the droplet." So, for purposes of the instant invention
with
Re >> mm, the planar surface tension values will be used.
[00169] Per A Spray Interaction Model with Application to Surface Film
Wettingõ
"Much of the behavior of impinging droplets can be characterized by the Weber
number. The droplet Weber number (We), representing the ratio of inertial to
surface
tension forces, is given as We = pVI;n2 di /a (6) where Vi,n is the surface-
normal
incident velocity of the impinging droplet. For We < Wee, a droplet will
adhere to the
dry wall. For We -> We the droplet impingement will result in a splash. Awet
represents the roughness of the surface, La is the droplet Laplace number, and
denotes
the ratio of surface tension force to viscous force in the droplet, La =
padi/g2 ... where
p is the liquid density, a is the surface tension, di is the impinging droplet
diameter,
and g is the liquid viscosity." Table 2 therein shows 'adhesion' for Weber
numbers
below 1, 'bouncing' for Weber numbers between about 1 and 20, adhesion again
for
Weber numbers between 20 and (Awet = La- =183), and 'splashing' for numbers
greater
than (Awet = LaT 183). From Development of Methodology for Spray Impingement
Simulation, values of Atm as a function of surface roughness rs (gm) are as
follows in
pairs (rs, Awet) = (0.05, 5264), (0.14, 4534), (0.4, 2634), (3.1, 2056), (12,
1322)
[00170] The formula for the Weber number suggests higher velocities and larger
droplets have higher Weber numbers, and thus a greater likelihood of bouncing.
The
data gathered for water density shows little change from -34 C to +25 C, while
the
surface tension for water is markedly higher at -34 C compared to 25 C, and
since the
Weber number is inversely proportional to surface tension, higher temperatures
increase the chance of bouncing (all other things being equal). Using water
droplets at
-34 C may have other benefits, e.g., slowing the diffusion of water through
bread (see
,e.g., Diffusion of water in food materials - a literature review discussed
herein),
slowing the evaporation of droplets (see the discussion herein re: the vapor
pressure of
water being lower at colder temperatures, with lower vapor pressures resulting
in
lower evaporation), and raising the critical RH for mold growth (see, e.g.,
Eq. 6.4 in
Predicting the Microbial Risk in Flooded London Dwellings Using Microbial,
Hygrothermal, and GIS Modelling).
[00171] Biological Stressors:
[001721 11 ormesi s "a biological phenomenon, where a biological system
stimulates beneficial responses at low doses of stressors that are otherwise
harmful to
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that system " Postharvest pathology of fresh horticultural produce (ISBN
9781138630833). In an exemplary embodiment, this approach is used in plants to
combat pathogens in combination with the scattering approach of the instant
invention.
1001731 The opposite, and perhaps more common effect, is where stressors are
actually harmful to a system. For example, certain stressors applied to
microbes
minimize their growth rate and increase the microbial lag.
1001741 It is suggested that UV-B may be a stressor for fungi. See, e.g.,
Ultraviolet Radiation From a Plant Perspective. The Plant-Microorganism
Context.
Thus, in one exemplary embodiment, UV-B is used before, during, and/or after U
VC
treatment to stress microbes to minimize growth. Characterization of damage on
Listeria innocua surviving to pulsed light - Effect on growth. DNA and
proteoine
cites a 13-fold increase in microbial lag after certain exposure to UVC.
1001751 "Many authors studied the effect of stress factors, i.e., pH,
temperature,
etc., on the distribution of individual cell lag times (Me'tris et al., 2002;
Smelt et al.,
2002; Francois et al., 2003b). They observed that when stress factors
increase, the
mean lag time is higher and the distribution becomes broader (increasing
variability)." Predictive modelling of the microbial lag phase: a review.
1001761 One embodiment of the instant invention is to therefore change the pH
of
the source water to the atomizer away from neutral to stress the microbes. The
pH
level can be adjusted in many ways, including with food safe additives (baking
powder to increase the pH, and lemon juice to decrease it). Thus, in preferred
embodiments, microbes are stressed before, during, and/or after UVC dry fog
scattering treatments to retard growth.
1001771 "Recently advanced oxidation processes (A0Ps) have been widely
investigated to develop effective treatment processes for the removal of
emerging
aqueous pollutants including natural organic matters (NOMs), disinfection by-
products (DBPs), endocrine disrupting compounds (EDCs), pharmaceuticals and
personal care products (PPCPs), and heavy metals [1-151 AOPs can also
effectively degrade other conventional recalcitrant pollutants such as
phenols, dyes,
and chlorinated compounds [16-29]. Highly reactive oxidizing species such as
hydroxyl radical (.0H), perhydroxyl radical (=0011), and hydrogen peroxide
(11202)
generated in AOPs are enable to effectively degrade and mineralize the above
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aqueous pollutants due to their high oxidation potentials as shown in Table 1
[30].
AOPs are divided into three categories. The first category is the chemical-
based
processes which include ozonolysis (03) and Fenton's oxidation (Fe2+ and
H202).
These chemical-based processes are considered as early-stage AOPs and involve
the
use of oxidizing chemicals and reactive radicals. The second category is the
wave-
energy-based processes, namely, photolysis (ultraviolet, UV), photocatalysis
(UV/Ti02), UV/H202 processes, sonolysis (ultrasound, US), and microwave (MW)
processes. The third category is the combined processes of AOPs including
sonophotolysis (UV/US), sonophotocatalysis (UV/US/Ti02), UV/ozone processes,
UV/Fenton processes, and US/Fenton processes. These combined AOPs can be
synergistically effective in terms of reaction efficiency, input chemical
consumption,
energy consumption, and reaction time. Table 2 shows degradation/radical
oxidation
reaction mechanisms in various AOPs [2, 4, 16, 18, 28, 30-37]. ... As Petrier
et al.
[68] briefly summarized, it is believed that volatile compounds undergo direct
pyrolysis inside the cavitation bubble, while less volatile compounds are
degraded by
highly reactive radical species such as OH radical on the bubble surface (Fig.
4)."
(Son, Advanced Oxidation Processes tising Ultrasound Technology for Water and
Wastewater Treatment, p/o Handbook of Ultrasonics and Sonochemistry, 2016,
ISBN
978-981-287-277-7). Thus, AOP activity can be induced by the UVC (or other) in
the
fog liquid, adding a second mechanism to stress/kill microbes in addition to
the UVC
directly damaging the DNA (and other structures). AOP can also be added as a
separate step of the germicidal process. "A treatment chamber based on
spraying
peroxide on produce whilst under constant illumination by UV-C (254 nm) was
assessed for inactivating human pathogens (E. coli 0157:H7; Salmonella) and
spoilage bacteria (Pectobacterium, Pseudomonas) introduced on and within a
range of
fresh produce (Hadjok, Mittal & Warriner, 2008). It was found that a treatment
using
30-second UV-C, 1.5% hydrogen peroxide at 50 C resulted in > 4 log cfu
eduction of
Salmonella on and within shredded lettuce. It was found that using hydrogen
peroxide
or UV alone supported 1 to 2 log cfu reduction, as did applying the AOP at 20
C
compared to 50 C (Hadjok et al., 2008). This demonstrated that using a
combination
of UV-C and peroxide at 50 C provided synergistic decontamination efficiency."
AOP for Surface Disinfection of Fresh Produce From Concept to Commercial
Reality UV Solutions.
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1001781 The growth of microorganisms in food can lead to extremes such as
spoilage (e.g., mold) on one end, and toxic effects (from the pathogen and/or
its
secretions/byproducts) on the other, e.g., listeria, E. coli 0157:H7 and
Salmonella,
and many others. Toxic effects are characterized by the ratings for severity:
(i)
5 fatality, (ii) serious illness, (iii) product recall, (iv) customer
complaint, and (v) not
signifcant. See Rahman, MS (eds), Handbook of Food Preservation, 3rd ed., CRC
Press; 2020, ISBN 978-1-4987-4048-7. Thus, the goal for acceptable levels in
germicidal disinfection is to stay in category (v).
1001791 "The most common foodborne infections causing gastrointestinal
10 disturbances are due to the pathogens such as Salmonella, Novovirus,
Staphylococcus
aureus, Shigella, and Campylobactor. . The foodbome illnesses caused by
Clostridium
botulinum, pathogenic Escherichia colt 0157:117 and 0104:114, Listeria spp.,
and
Vibrio spp. have been reported to be much more severe, causing symptoms
extending
from bloody diarrhea to neonatal death and fatality in some acutely infected
adults
15 (Callejon et al., 2015; Kirk et al., 2015)." Bhilwadikar, et al,
Decontamination of
microorganisms and pesticides from fresh fruits and vegetables: a
comprehensive
review from common household processes to modem techniques, Comprehensive
reviews in food science and food safety 18.4 (2019): 1003-1038, that also
cited
appropriate 1JVC dosage for specific log reductions of many microorganisms.
20 1001801 When exposing an object, e.g., food, to high RH (such as during
dry fog
scattering), the thought of promoting mold (fungal) growth comes to mind. The
temporal effect of high RH relative to mold growth has been discussed in a
number of
models, including "Time of Wetness" or 'TOW', which has also been used to cite
bacterial (and other) growth as well. In fact, the teachings herein should be
considered
25 with all microbes, including pathogens. The research/models generally
relate to high
RH on the order of hours and days, and some, like TOW, are based on high-RH
cycles. Note that the specific microbe, the growth medium, and other factors
as will
be discussed play roles in interpreting existing data for use in the instant
invention.
However, there are trends that are important to understand. Note that
references to
30 TOW is not meant to promote the specific TOW model for mold growth
(there are
many different models, as cited below). It is being used because it is
descriptive and
meant herein to generically encompass mold growth models.
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1001811 Unlike mold growth in the cyclic TOW model, in an exemplary
embodiment of the instant invention, a single high-RH cycle would span seconds
or
minutes (typical time spans that food articles spend in UV tunnels). However,
the
testing and modeling of TOW and related research are instructive in performing
mold-
related risk assessments for the instant invention, including model
development. Such
a model could inform the necessary irradiance required to reach a desired
fluence as
described below.
1001821 In an exemplary embodiment, a food processing facility uses a UVC
tunnel to disinfect certain food products. In order to derive the necessary
operating
parameters for the UVC tunnel with dry fog, the following exemplary tests are
conducted in accordance with good Design of Experiment } and biological
testing
procedures. Note that for brevity, intermediate cleaning of the processing
equipment
is not cited below.
1001831 1) Coupons inoculated with various microbiota are prepared and one set
of
samples are taken, cultured, and data is recorded. The microbiota should be
those
expected to be found at food processing facilities (both on the food and in
the local
environment, including mold spores), or suitable surrogates
1001841 2) Another sample of coupons is run through the tunnel with UVC and
without dry fog, and at several belt speeds. Cultures are obtained and data is
recorded.
1001851 3) Another sample of coupons are run through the tunnel without UVC,
but this time with dry fog at several concentrations, and at the above belt
speeds.
Cultures are obtained and data is recorded.
1001861 4) The same test directly above is run, this time the coupons are
dried after
running through the tunnel. Cultures are obtained and data is recorded.
[00187] 5) Yet another sample of coupons is run through the tunnel, this time
with
both UVC and dry fog, at the belt speeds and dry fog concentrations used in
the
previous tests, and at different intensities as measured by dosimeter pucks on
the belt
(e.g., by varying lamp power and/or moving the lamps at different distances to
the
products). Cultures are obtained and data is recorded.
[001881 6) Further testing can be conducted to understand the effects such as
stressing the microbiota before and/or after UVC/dry-fog, or combining UVC
with
synergistic non-photochemical/photophysical modality with kinetic effects, as
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described in this application and related applications of the instant
invention, as well
as those known in the art.
1001891 7) A model is constructed that isolates the effects of dry fog on the
growth
of different types of microbes, if any, based on the variables cited above.
1001901 8) The intensity of irradiation is then defined to ensure the TOW is
below
the threshold (if any) while meeting the fluence required to achieve the
necessary log
reduction requirements for the microbes of interest in the food processing
facilities.
1001911 A method to avoid the effects of RH is to isolate the fog chamber from
the
food products. Several UVGI applications require very dry conditions, e.g., to
prevent clumping in powders like flour.
1001921 Figure 10 shows such an arrangement resulting, with the test data
shown
in Figure 14. Here the visible light sensor was placed inside a polycarbonate
tube that
was wrapped with one winding of black vinyl tape, shadowing the sensor. The
inside
of the tube, including the shadowed visible sensor inside, was isolated from
the fog
that surrounded it (the ends of the tube protruded through bulkhead connectors
seal
to the chamber walls, thus exposing the inside of the tube to ambient air and
not dry
fog, and the wire from the sensor exiting one end of the tube). This clearly
demonstrates the ability of scattered light to reach an isolated target (the
sensor)
when shadowed (here by black tape around the tube).
1001931 Another embodiment for avoiding wetness includes the use small dry-ice
crystals for use as scatterers, which then sublimates, instead of condensing.
1001941 In another embodiment, the use of air currents/curtains keep dry fog
from
touching products. A scattering fog formed into an air current sheet for use
as a
projection screen is taught using an array of straws in Rakkolainen, et al,
Walk-thru
screen, Projection Displays V111. Vol. 4657, International Society for Optics
and
Photonics, 2002). Air currents are contemplated as an approach to force away
moisture, as dry fog can be easily moved by air currents. For example, a loaf
of bread
can be surrounded at each corner by small diameter tubing with nozzles
optimized to
push away (or vacuum locally or create local vortices to keep the moisture
airborne)
dry fog that comes near its immediate surface, but minimally effecting the dry
fog
number concentration (needed for scattering) more than say one centimeter
away.
1001951 In another embodiment, targets are electrostatically charged (or
comprise a
net charge during processing) and the scattering fog is charged to the same
polarity
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such that the dry fog droplets are repelled as they approach the target. Note
that
"Shimolcawa et al. reported that ultrasonic mist generated from high-purity
water has
a negative charge ..." Effect of ultrasonic frequency on size distributions of
nanosized
mist generated by ultrasonic atomization, and thus the use of high-purity
water for the
dry fog would be repelled from a negatively charged target.
1001961 "Water has a polar molecular structure and has a large value of
electric
dipole moment due to hydrogen covalent bonds. The electron-pair forming
covalent
bond gets attracted towards the oxygen atom and as a result, oxygen side gets
slight
negative polarity and hydrogen side gets positive polarity and It produce an
electric
dipole moment inside the water molecule. according to the electrochemistry of
polar
molecules, fine water droplets can be charged electrostatically." Economical
Way of
Appling Pesticides Through Electrostatic Sprayer. Thus, a product can be
charged (or
it can be surrounded by a charged wire/mesh) with the same polarity as the
water
droplets, thus repelling water droplets from landing on the product. The
strength of
the charges can be adjusted to optimize an overall system efficacy metric,
which can
be defined as some formula whose factors include electrical power consumption,
log
reduction of pathogens, factory production rate, maintenance costs, etc Note
for
safety the wires/mesh can be charged to a potential only within the UVC
tunnel.
1001971 In another embodiment, charged food-safe powders can be used for the
scattering field. After irradiation, the powder residue can be washed-off (if
desired) in
a liquid solution that also neutralizes the surface charge(s). The powder can
also form
a desirable coating that is left on the food article.
1001981 As cited e.g., in Effects of charging voltage,
application speed. target
height, and orientation upon charged spray deposition on leaf abaxial and
adaxial
surfaces, fogging systems have successfully used electrostatics to enhance the
attachment of spray bubbles to targets (e.g., produce) including the underside
of
leaves (a surface in shadow). So, if a fog bubble can reach a surface in
shadow, then
there exists a trajectory for UVC rays to reach the same surface hopping from
bubble
to bubble.
1001991 If using electrostatic sprays, a number of parameters must be
selected, such
as the choice of charge(s) of the spray and the target(s), i.e., positive,
negative, or
neutral, the relative and absolute amplitudes of the charges, their spatial
and temporal
variations, and spray distances The effects of charge vs particle size as it
relates to
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'wrap-around', as well as other parameters can be found in Effects of charging
voltage, application speed. target height, and orientation upon charged spray
deposition on leaf abaxial and adaxial surfaces, Real-Time Control of Spray
Drop
Application, Effects of electrode voltage, liquid flow rate, and liquid
properties on
spray chargeability of an air-assisted electrostatic-induction spray-charging
system,
Penetration Of N95 Filtering Facepiece Respirators By Charged And Charge-
Neutralized Nanoparticles, Bacterial Attachment to Meat Surfaces. A baseline
spray
distance for maximum front-side and back-side coverage is on the order of
400mm to
500mm or roughly 15" to 20". The Experimental study of the spray distance
electrostatic spray. The optimum for a given application requires testing as
the cited
study was for one basic 'paper-card' test configuration, thus not coveting all
the
possible variables such as airflow, target charge(s), etc.; however, the paper
helps
define a repeatable testing procedure. Note also that electrostatic sprayer
manufacturers also provide guidelines, e.g. for the PX200ES (Protexus PX200ES
Brochure, EarthSafe, Braintree, MA), the recommended distance is 3ft to 6 ft.
1002001 Where moisture is not an issue, an attractive approach to
electrostatics is to
facilitate scattering particles getting close to the targets, which are
oppositely charged
Also, e.g., after irradiation, a puff of a neutralizing medium can be directed
at the food
surfaces to minimize electrostatic attraction from pathogens and detritus.
1002011 Electrostatics is used, e.g., in agricultural pesticide spraying and
PPE
decontamination, but it can also cause bacterial attachment to meat surfaces
and
hydrophobic/hydrophilic surfaces. Detailed design criteria for electrostatic
spraying
are also referenced, e.g., in Effects of charging voltage, application speed.
target
height, and orientation upon charged spray deposition on leaf abaxial and
adaxial
surfaces, The Experimental study of the spray distance electrostatic spray.
Influence
of droplet size, air-assistance, and electrostatic charge upon the
distribution of
ultralow-volume sprays on tomatoes.
1002021 For some exemplary applications, static charges may need to be
eliminated
before/during/after UVC dry fog scattering. An exemplary neutralizer is MSP
Model
1090 Electrical Ionizer from MSP Corporation (Shoreview, Minnesota, a division
of
TSI Inc.). For other exemplary applications, a scattering aerosol may need to
be
neutralized if the target is charged and thus prevents scattering particles
from getting
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near the surface. See, e.g., US8605406 Apparatus and methods for altering
charge on
a dielectric material.
1002031 Discussions of charges in water are found in Water with Excess
Electric
Charge and Can Water Store Charge. The effect of humidity on charge is
discussed in
5 Atmospheric humidity and particle charging state on agglomeration of
aerosol
particles discusses.
1002041 In yet another exemplary embodiment, the powder
particles themselves
can be used to scatter UVC to other particles by creating a cloud of particles
at a
sufficient number concentration, assuming the reflectance is high enough to
meet
10 practical efficacies for a given application.
1002051 Like most materials, UVC reflectance of certain powders can be quite
low.
See
'reflection absorbance spectra of flours' in Front-Surface Absorbance Spectra
of
Wheat Flour - Determination of Carotenoids. It appears the cited flours have a
front-
15 surface 'reflection absorbance' (at a 30 angle of incidence) of 0.8 to
0.85 in the
UVC wavelength range around 275nm, yielding reflectance values between about
10(-
("5)=14 1% to 10('.8)=15 /3% Note, "However, it must be emphasized that in the
front-surface reflectance measurements the light path length is not clearly
defined as
in transmittance spectroscopy where this length is generally coincident with
the
20 distance between the windows of the sample cell. In fact, in the case of
powders, each
photon passes through an extremely heterogeneous sample and its path length
depends
on the scattering processes it encounters; thus, only an average path length
can be
defined, which, unfortunately, cannot be measured or calculated in a simple
way."
1002061 Fog isolated from products - Figure 8 details another exemplary
25 embodiment, where the dry fog and the powders are isolated within
concentric
cylinders. The visible light dry fog testing herein proved that dry fog can be
isolated
from a surface and yet still provide effective illumination of surfaces in
shadow (recall
the paddle of the visible laser power meter, UT385, within the polycarbonate
tube).
As shown in Figure 8, the fog cloud efficiently moves the emission of UVC rays
from
30 an exemplary LP mercury lamp to the exterior of the inner UV
transmissive cylinder,
acting almost like a relay lens. See the Figure for other details. A suitable
baseline
cylindrical UVC LED reactor is described in US20200247689 Method, System and
Apparatus for Treatment of Fluids (produced commercially by Typhon Treatment
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Systems Ltd., Penrith, England), which can then surround the inner UV
transmissive
cylinder (both scaled in diameter as appropriate).
1002071 In Figure 8, UVC transmissive (e.g., UV grade fused silica or UVGFS)
concentric tubes are utilized with a tubular low pressure (LP) mercury lamp at
the
center. UVC from the lamp (itself isolated from the fog using FEP/UVGFS tubing
like LP lamps isolated from water in UVGI disinfection systems) passes through
a
scattering dry fog within the middle cylindrical section and forward scatters
to the
dry powder that is isolated in the outer cylindrical section. Every point on
the
circumference of the UV transmissive inner cylinder receives scattered rays
from the
dry fog over a wide range of angles, effectively creating a larger diffuse
emitter
surface that directs UVC into the powder.
1002081 Any UVC that passes through the power then passes through the outer
wall of another UVC transmissive tube which has been surrounded with a high
reflective diffuse UVC reflector such as Porex Virtek Reflective PTFE (Porex
Corporation, Fairburn, Georgia), causing the UVC to bounce back over a range
of
angles for a chance to strike more powder. UVC that makes it past the powder
will
be re-scattered by the fog field to begin the cycle again
1002091 This is a very efficient process because the Porex reflector has an
average
reflectivity of 97% at 254nm, and the fog has effectively no absorption when
the
source water has been adequately filtered from absorbing particulates. Monte
Carlo
scattering simulations and optical ray tracing (the latter including the
effects of
reflector absorbance and lamp plasma absorbances as described in Validation of
Discrete Ordinate Radiation Model for Application in UV Air Disinfection
Modeling) can be used to define the maximum water absorbance based on overall
system efficacy requirements. Water absorbance is discussed, e.g., in
Christensen, et
al., How particles affect UV light in the UV disinfection of unfiltered
drinking water,
Journal-American Water Works Association 95.4 (2003): 179-189.
1002101 Note that the gap size of the annular region within which the dry
powder
flows is chosen based on the needs of the application, weighting such factors
as (a)
low pressure drop, (b) high dosage uniformity, (c) power efficacy, (d) product
throughput, etc. Air flow of the appropriate humidity (to prevent clumping)
can be
introduced to swirl the powder (e.g., flour) for better dosage uniformity.
Swirling is
done in UVC water treatment systems to improve fluence coverage, and also in
the
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swirl-drying of coal, see Simanjuntak, et al, Experimental Study on The Effect
of
Angle of Blade Inclination on Coal Swirl Fluidized Bed Drying, ARPN J. Eng.
App!.
Sci 11.2 (2016): 12499-12505., and powder-like foods such as wheat grains, see
Ozbey, et al, Effect of swirling flow on fluidized bed drying of wheat grains,
Energy
conversion and management 46.9-10 (2005): 1495-1512.
1002111 Alternate embodiments can be constructed via UVC LEDs and planar
vessels for the fog and the powder. Whether cylindrical, planar, or other,
this
approach provides a modular construction technique that can be arranged in
geometric
shapes such as arrays of cylinders (including nested cylinders, or arrays such
as are
found in electric car battery packs) and layers of planar vessels (alternating
fog
vessels and powder vessels). Optimization of reactor geometry for a given
product
flow rate can be performed by Design of Experiments (DOE) using both
simulations
and lab testing. See, e.g., Design and Analysis of Experiments, ISBN 978-3-319-
52248-7.
1002121 In another embodiment of an isolated system, dry fog is used (or
bubbles
in water) to determine the necessary scattering to disinfect food powders,
seeds, etc.
The number concentration and fog thicknesses are determined, and an equivalent
scattering profile (or one that is reasonably close) is fabricated on-or-in a
highly UVC
transmissive material (surface scattering vs volume scattering). Thus, the dry
fog (or
bubble) scattering is used for guiding the fabrication of a scattering element
that is
then used in an isolated system. An example of the design of a volume
scattering
material for visible light is cited herein, bribe, et al, Brighter Backlights
Using
Highly Scattered Optical Transmission Polymer, SID Symposium Digest, Vol.26.
pp.379-381, 1995. See also Research of diffusing plates for LCD backlights,
and
Design guidance of backlight optic for improvement of the brightness in the
conventional edge-lit LCD backlight, Engineered surface scatterers in edge-lit
slab
waveguides to improve light delivery in algae cultivation. Of course, there
are
advantages of using the dry fog, in that the concentration can be modified as
needed
based, e.g., using adaptive feedback to optimize the scattering with changes
in the
flow and the properties of the powder-like material to be disinfected.
1002131 Fog isolated from the UV source (and other processing equipment) such
as in UV tunnel retrofit/forward-fit applications:
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100214.1 Another exemplary embodiment is a UVC transmissive rectangular box
(made from FEP and/or UVGFS in UVC compatible frames) that contains objects to
be disinfected and rides through a UV tunnel, either directly on the conveyor
belt, or
along rails that pass through the tunnel. This approach can be used in both
retrofit or
forward-fit applications.
1002151 In one embodiment, dry fog is generated within the box structure. In
another embodiment, as shown in Figure 7, dry fog is routed to the box via one
or
more sanitary conduits whose external material is compatible with intense UVC.
In
one embodiment, the conduit can be one or more sanitary hoses of sufficient
diameter
to supply the box with a fog concentration sufficiently high to meet
scattering
requirements. Sanitary (and other) large/small diameter hoses and fittings are
available, e.g., from United States Plastic Corporation (Lima, 010 with
varying
degrees of UV resistance. To achieve long life in the high intensity UV tunnel
environment, the hose can be fabricated from PTFE, aluminum, stainless steel,
UVC
resistant polypropylene, or custom fabricated from a polymer with a high
degree of
UVC absorbing material. Alternatively, the hose can be coated/painted or
surrounded
by protective flexible sleeving such as Thermashield from Techflex, Inc
(Sparta, NJ)
Fiberglass insulation or forced cool air can be interjected between the hose
and
sleeving to further minimize dry fog evaporation as the hose passes near the
hot UVC
lamps within the tunnel. The box can also comprise double walls and/or active
or
passive cooling towards this end as well. In one embodiment, the UV tunnel is
fitted
with forced ambient air or forced cooling air to minimize dry fog evaporation
in the
hoses and box.
1002161 A 3-way valve can be used to switch from the dry fog generation system
to
the evacuation system (a vacuum/negative-pressure system and/or via purging
the
contents with clean dry air/gas in a flow-through arrangement, not shown).
Large
diameter plastic 3-way valves are available, e.g., from FibroPool (St. Louis.
MS), and
in stainless steel (sanitary) from Valtorc International (Kennesaw, GA). Flow-
through
designs ensures that fog that has been used is removed and not recycled (in
case it
gets contaminated akin to UVC-based wash-water disinfection systems).
100211 In another exemplary embodiment, the box rides on stainless steel rails
that run along opposing sides inside the tunnel. The rails are made of hollow
pipe
through which dry fog is mounted. In one embodiment, one rail carries the thy
fog to
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the box, the other rail is used to evacuate the fog from the box. Paddles (UVC
compatible material) connected to the conveyor belt push the box along the
rails. In an
exemplary embodiment, the paddles are U-shaped to prevent the box from skewing
and jamming in the tunnel as it is being pushed, while minimizing any
shadowing of
the UVC.
1002181 In yet another embodiment, the box is self-contained with an
ultrasonic
atomizer attached to the side of the fog chamber portion. Within the fog
chamber
portion, the UVC transparent windows are tilted a few degrees so that
condensate can
drip towards a channel or moat along the bottom. This prevents pooling in the
path of
central region of the box, potentially adding variability to the fluence
depending upon
environmental conditions. Fresh film can also be dragged across the box as
described
in applicant's US6485164 Lighting device with perpetually clean lens. It is
important
to note that the fog is constantly irradiated with UVC, and in one embodiment
is
recycled via condensation for continual use. In another embodiment, customers
may
have concern that the fog condensate may trap pathogens. In this case, the fog
is
safely disposed after irradiation (e.g. via a HEPA-equipped wet/dry vacuum).
Note
also that the fog evacuation/drying can start during different phases of the
cycle For
example, it can start at the tail-end of the irradiation cycle and completed
before
irradiation ceases to illuminate the target. This is an extra precaution to
minimize the
risk that the fog carries pathogens.
1.00219] The box is fitted with one or more scatterometers. For example, a
disclosed herein, one or more lasers directing their beam(s) into the box
through a
region of fog, and corresponding sensors at a fixed distance away to measure
the
transmittance to compare with fog-free values, where this data is compared to
Monte
Carlo scattering simulations as disclosed herein to arrive at an approximate
concentration to provide feedback to the control system to regulate the dry
fog
concentration. A thorough discussion of mathematical modeling of intensity vs
scattering over distance using an adaptation of the Beer-Lambert law via
correction
factors can be found in Laser light scattering in turbid media Part I -
Experimental and
simulated results for the spatial intensity distribution, Laser light
scattering in turbid
media Part II: Spatial and temporal analysis of individual scattering orders
via Monte
Carlo simulation.
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1002201 So, in an exemplary embodiment, the size distribution of a dry fog
generated by a 1.7MHz ultrasonic transducer array is characterized by a
precision
instrument, e.g., the Spraytec laser diffraction system from Malvern
Panalytical
Inc.(Westborough, MA) that is specified to detect sizes down to 0.1 micron.
The
5 measurement is performed either in-situ (e.g., within a UVC tunnel), or
in a controlled
experiment that emulates a similar aerosol environment (accounting for RH,
temperature, geometry size/obstructions, and the effects of evaporation,
coalescence,
and the like). The number concentration, Nd, is computed as described in
Measuring
resolution degradation of long-wavelength infrared imagery in fog.
10 1002211 The particle distribution is then input in a Monte Carlo
simulation program
such as MontCarl. A large number of simulations are run to characterize the
effects of
Nd, wavelength, and layer thickness on transmission through the fog, as well
on the
scattering profiles and parametrics (e.g., tts, a, path length, etc.) as
needed for
augmenting the Beer-Lambert equation. Two wavelengths of interest would be
15 simulated for the case of both the UVC treatment wavelength (depending
upon
whether 254nm sources are used, or UVC LEDs are used in the region between
about
265nm and 280nm) and a proxy wavelength for a solid state laser (e.g., 635nm)
to
characterize the fog field as disclosed herein (i.e., disclosed in one or more
of the
applications related to the instant invention). As an aside, Far UV-C
radiation can also
20 be used in the embodiments herein, see e.g., 222nm KrC1 lamps as cited
in Far UV-C
Radiation - Current State-of Knowledge, 2021. The proxy wavelength should be
chosen to have similar scattering characteristics through the dry fog as the
UVC. Once
a proxy wavelength has been chosen, the Monte Carlo simulation data is
reviewed to
determine one or more suitable locations for measuring the proxy scattering
intensity.
25 During initial testing, the collection angle of the proxy sensor(s)
should be established
that ensure healthy signal to noise ratios, while addressing the concerns as
cited in the
above reference articles. Initial testing must also determine the number of
proxy
sensors and their spatial distance/orientation relative to the beam angle from
the solid
state light source in order to provide an estimate of the 1=1d of the fog in
situ, which is
30 needed to ensure the appropriate level of scattering to reach surfaces
in shadow. In
certain exemplary embodiments, the Nd value will be used to regulate the
distance of
the UVC source(s) to the products (and change conveyor belt speed as
necessary) to
maintain the proper dosage. In some applications, better discrimination can be
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afforded by measuring optical power at two or more angles, computing the
relative
power ratios at different angles relative to the axis of the proxy beam
without fog, and
comparing the results to predictions from Monte Carlo simulations. Each
application
may have unique requirements due to, e.g., geometric limitations in the
available
space to incorporate the invention. The extent of the teachings herein
provides one of
skill in the art overarching guidance to resolve implementation issues,
whether
directly or by providing leads to authors in relevant papers or other third
parties that
can provide support via theory/analytics/simulation and/or experimentation.
Further
reference for problem solving and creating a robust deign is made to Design
and
Analysis of Experiments (ISBN 978-3-319-52248-7).
1002221 In the exemplary embodiment, the transmittance through a distance of
the
dry fog (and through the same distance without the dry fog) is measured using
a
635nm solid state laser light source, 3mW, available from Roithner
Lasertechnik
GmbH (Vienna, Austria), P/N LDM635/3LJ. The power is measured using a silicon
PIN photodiode designed for optical power meters, such as the Hamamatsu
Photonics,
K.K (Hamamatsu City, Japan) P/N S3994-01, which is also fitted with a glass
window
for protection and thus can be sealed to avoid any concerns of dry fog effects
on
electronics. A pinhole aperture can be used to limit the field of view of the
sensor.
The sensor can also be optically filtered to avoid contamination by the UVC
sources,
ambient light, etc. and then generating /or (b) estimating as cited herein by
measuring
the intensity of a source at different angles through the dry fog and then
comparing
results to a database constructed from Monte Carlo simulations.
1002231 With the system constructed as discussed, calibration testing can
begin
using at first UVC dosimeters to ensure the dosing of surfaces not in shadow
meets
the requirements. Then the dosimetric avatars, as explained herein, can be
used to test
the surfaces in shadow. Note that 3D surface disinfection modelling is
described in
UV intensity measurement and modelling and disinfection performance prediction
for
irradiation of solid surfaces with UV light. See also US9555144 Hard surface
disinfection system and method. Once confirmed, the appropriate feedback
control
elements can be used to test for sensitivities in design parameters, and the
closed loop
control system can be implemented in hardware/ software (see, e.g., Feedback
Control
of Dynamic Systems, ISBN 978-0-13-349659-8). Environmental and other product
development testing can be conducted (see, e.g., Next generation HALT and HASS
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robust design of electronics and systems (ISBN 978-1-118-70023-5), and then
trial
runs with real products can be conducted over a range of throughput rates in
laboratory and factory settings. For UVC treatment systems, lab testing will
include
actual pathogen testing (see, e.g., Ultraviolet Light in Food Technology-
Principles
and Applications, ISBN 978-1-138-08142-0).
1002241 In another exemplary embodiment, the UVC source itself (i.e., no proxy
source) can be used to determine the scattering profiles. For example, one
sensor can
be placed adjacent to a UVC source (with the appropriate filtering to avoid
oversaturation and contamination from other light sources) and one or more in
the far
field, where all other UVC sources other than the one with the sensor can be
pulsed
off so that the UVC sensor can be correlated to the appropriate source (not
all sources
in an array, for example, will be at the same inherent intensity). See also
the instant
inventor's US8937443 Systems and methods for controlline light sources, that
discusses how to measure multiple light sources and control their emittance,
especially suitable in the instant application for an array of UVC LEDs. For
example,
the '443 discloses in Claim 8 "A method for controlling light output of an
array
comprising a plurality of series-connected of light sources by a controller
while
maintaining a desired operating emittance of the array, the method comprising:
during
a first time period, pulsing current to a light source, wherein the light
source is pulsed
at a higher emittance; sampling the light of the array by an optical sensor
during the
first time period and during a second time period when the current is not
increased;
determining a difference in luminance between the first and second time
periods;
comparing the difference in luminance to an emittance value stored in a memory
associated with the shunted light source; and subsequently controlling the
current
based on the comparison, wherein the subsequent controlling produces the
desired
operating emittance of the array." Claim 13 uses a ramp instead of a pulse.
These
techniques were used to avoid visual artifacts during normal operation in the
'443,
whereas in the instant invention, UVC is invisible, although it still can be
used, and in
fact these techniques can be used for a visible proxy in the instant
application, or for
the Vis/N111 scattering application for greenhouses as disclosed herein.
1002251 Now, turning back to the isolated box in a UV tunnel, by using rails,
one
or more boxes can operate simultaneously. In one embodiment, the rail is
fitted with a
brush seal along one face that contains the fog within the rail. A hollow
member on
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the box protrudes through the bristles locally, allowing fog to enter the box.
See, e.g.,
the brush bristles as taught in US8769890 Device for feeding one or more lines
through an opening in a wall or a floor. The construction materials must
ensure the
bristles do not rapidly degrade in UVC, nor trap detritus that could lead to
microbial
growth. See also Claim 18 of US10493176 Curtain sanitizer device and method of
using the same, citing brush seals that blocks UVC. Alternatives to brush
seals are
also contemplated, such as an accordion-style magnetic seal like what is used
on
refrigerator doors, PTFE foam, air curtains, strip seals, zipper arrangements,
and the
like. In one embodiment, a magnetic door gasket is fabricated, and are
available in
custom form from TR1COMP, INC. (Pompton Plains, NJ). The protruding tube from
the box is thin with a triangular-like cross section to lift (and release) the
seal locally
with a small displacement to minimize gaps in the seal between rail and box to
avoid
dumping dry fog into the tunnel.
1002261 In any enclosed box configuration, an optional HEPA filter (e.g.,
Nilfisk
Flat PTFE-coated filter, P/N 107413540) is attached to the box to allow air to
pass
through, but not the desired range of droplet sizes (or other solid scatterers
if used).
This prevents backpressure from building that would limit the fog mover from
building up sufficient dry fog concentration in the box. The PTFE provides
protection
against the intense UVC in the tunnel. These specific filters are sold for the
Niffisk
Pty Ltd. (Amdell Park, Australia) Attix 33/44 line of wet/dry vacuum cleaners.
The
operation is akin to the use of the MERV 16 filter cited herein with reference
to
Figures 20 and 21. The HEPA filter is also used when evacuating the box,
enabling
(dry) ambient filtered air into the box for an effective flushing action. The
ambient air
in and around the tunnel can be kept at a low RH to promote an effective
flushing/drying process. The output side of the HEPA filter (furthest from the
box
interior) can also be fitted with a desiccant or other drying means.
Desiccants are
available, e.g., from Multisorb Filtration Group (Buffalo, New York).
1002271 Note also "Since water particles present in visible vapor range from 2
to 40
microns, these particles are trapped by high efficiency filters. Some types of
filters
absorb moisture and expand, reducing air flow through the filter material. As
a result,
the static pressure in the duct rises from normal (about 1" water gauge) to as
high as
40" wg. When the filter absorbs moisture, it also releases the latent heat of
condensed
steam into the duct air. When a humidifier manifold is located too close to an
absolute
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filter, the filter collects water vapor, preventing the moisture from reaching
the space
to be humidified. Placing the humidifier manifold farther upstream allows the
water
vapor to change into steam gas, which will pass unhindered through an absolute
filter.
Under most circumstances, the water vapor will dissipate properly if the
humidifier
manifold is located at least 10 feet ahead of the final filter. ... Foggers
may be applied
in air handlers or ducts where the air velocity is less than 750 FPM. For duct
applications, if the air velocity is in excess of the recommended maximum, a
fogging
chamber with fog eliminator and drain pan should be considered. When a fogging
system cannot be practically applied to the existing mechanical system, a
Direct Area
Discharge Fogging System (DDF) might be the logical alternative. The "DDF"
designation indicates that foggers are individually located within an enclosed
area
such as a warehouse or factory floor, and fog is directly discharge into the
open
space." Humidification (Armstrong Flow Control). As an aside, this is an
excellent
reference on the principles of humidity and covers some aspects of wetting.
1002281 The Nilfisk filter is designed, however, for use in wet/dry vacuums
(likely
the reason for using a PTFE coating). Further, in fog applications, the flow
rates are
much lower than what would he found in a wet/dry vacuum cleaner (shop-vac)
However, high velocities are described herein to achieve a high enough Weber
number to cause bouncing of micron-sized dry fog droplets instead of adhesion
on dry
surfaces, but then the droplets would also bounce-off at least parts of the
filter surface.
1002291 Many other tunnel/box connections are possible, such as using one hose
to
feed dry fog, and another to prevent backpressure and then remove dry fog
after UVC
irradiation is completed. A flushing approach can be used whereby the dry fog
feeding hose is switched to feeding dry air while the other hose evacuates, or
check
valves mounted to the box open to the ambient drier air when negative pressure
is
applied by the evacuation system. Note that Nilfisk makes a line of wet/dry
vacuums
suitable for health and safety applications, as well as vacuums for food and
pharma. A
suitable check valve is the 'Thin Swing Check Valve - Stainless Steel, Series
9300',
available from JeLS Valve (Huffman, TX). The valves are sized from 2" to 24"
and
comprise a 'resilient seat' that 'allows for seating at low differential
pressure.' Note
that the torsional spring in the valve may need to be optimized for a given
pressure
differential. Note also that valves like this can also be made from polymeric
materials
to reduce cost.
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[00230] In one exemplary embodiment, the products are placed on trays or food
racks and then slid into one of a number of slots within the box that allows
different
fog thicknesses above and below the products. Trays can be fabricated from
stainless
steel wire belt material used for food conveyors such as Flexx Flow belting
from
5 Lumsden Belting Corp. (Lancaster, PA) The belt material is tightly strung
in a
stainless steel frame, making a type of food rack that would be used in an
oven. The
intent here is to keep the wires relatively thin to minimize equipment-induced
shadows, while being able to maintain product weight without blocking too much
UVC. A tight wire-to-wire spacing (e.g., 72 wires per linear foot, each wire
.050" in
10 diameter) also allows support for small diameter foods, e.g.,
blueberries and the like.
Alternatively, various box heights can be used to ensure equal fog thicknesses
on top
and bottom of the products. This can also be accomplished by adjusting the
position
of the top and/or bottom UVC transmissive plates relative to the position/slot
where
the products are positioned. Note also that the food tray/rack has apertures
for the
15 UVC to pass, however, some percentage of UVC is blocked. In addition,
the conveyor
belt itself that the box sits above also has similar apertures, whereas there
are no
obstructions above the products, and thus this imbalance in irradiation must
he
considered when adjusting lamp power from above and below.
[00231] =Note also that the box need not be used with a tunnel. For example,
the
20 box can be stationary, with the sop, bottom, and/or sides fitted with
UVC lamps, such
as UVC LED arrays. Of course, reflectors having very high UVC reflectance can
be
used on one or more sides, including between/behind lamps, e.g., Porex Virteke
Reflective PTFE (Porex Corporation, Fairburn, Georgia).
1002321 As in all UVC irradiation systems, rotating the product to be
disinfected
25 greatly aids dosage uniformity. Powders can be swirled in a similar
fashion as detailed
herein in the family of patent applications for the instant invention, see,
herein the
discussion of turbulence, swirl, jets, etc.'
[00233] Ultimately, the isolated scattering approach is very efficient,
because
regardless of whether the scattered rays transmit-through or reflect-from the
fog, they
30 still head toward the powder, assuming the absorbing lamp plasma
occupies a small
volume.
[00234] A similar embodiment would be items that are wrapped with UVC
transmissive material (e.g., FEP shrink wrap) that maintains isolation (mostly
or
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totally) between a food product and the dry fog. The shrink wrap allows the
dry fog
to come extremely close to the surface, which has a benefit as shown in Figure
6.
1002351 As an aside, one should consider the effects (good and bad) of
condensation on the shrink-wrapped package (and any windows, light sensors,
etc.),
causing diffusion of light (a useful thing to simulate in optical ray tracing)
as taught
e.g., in, Pollet, et al, Diffusion of radiation transmitted through dry and
condensate
covered transmitting materials, Solar Energy Materials and Solar Cells 86.2
(2005):
177-196. For example, sensors can be biased as a result of condensation. Light
from
certain angles may be refracted away from the target, although for certain
angles it
may aid the scattering performance. Approaches that use collimated light
sources may
be extremely sensitive to the condensation-induced diffusion.
1002361 Another embodiment to minimize any deleterious effects of water on a
target (food), would be to remove residual fog and humidity from the target
after
UVC irradiation like the vacuum/exhaust hood and dryer as shown in Figure 1.
Dryers include the use of desiccants, dry air, infrared and other heaters, and
the like.
1002371 In non-isolated systems, as mentioned previously, the degree of
wetness/condensation is a function of a number of variables as taught
previously in
the discussion on the critical Weber number, and the like.
1002381 In one group of embodiments, a control system monitors condensate and
adjusts parameters to minimize condensate while maintaining an adequate
scattering
profile for a given target. Thus, an exemplary target here is to meet the
scattering
profile while not oversaturating the air with dry fog, minimizing impaction-
induced
wetting, and avoiding having the surface of the food product at or below the
dew
point (e.g., by using certain surfaces of a UV tunnel as temperature-
controlled
programmable condensing spots to avoid condensing on food items). The
following
greenhouse control systems provide a somewhat analogous application for food
products (and a closely analogous approach for the visible/NM dry fog
scattering
enhancement to photosynthesis as described herein): "In this paper, we have
designed
and implemented a system that can understand the greenhouse environment and
the
state of crops by using sensors and optimize crop growth conditions with
emphasis on
the dew point condition. An automatic dew condensation control system combined
with a WSN was realized, which utilizes the dew point condition to prevent the
dew
condensation phenomenon on the leaf surfaces of crops that is believed to be
decisive
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in the outbreak of crop diseases. Also, a model similar to an actual
greenhouse
environment was made to verify the performance of the system presented and the
model was operated and monitored by applying the automatic dew condensation
control system. It can also cope with exceptional situations by providing the
greenhouse environment and information about a device's operating state to
users
every certain time. The topic to be researched in the future is the optimal
sensor
deployment in a real greenhouse for the automatic dew condensation control
system.
To apply the automatic dew condensation control system to an actual greenhouse
environment, we will have to gather more data about the real conditions and
refine our
system. Additionally, the building blocks composing the automatic dew
condensation
control system should be extended so that it can be applied to various
situations that
can occur in the actual greenhouse environment." Park, et al, Wireless sensor
network-based greenhouse environment monitoring and automatic control system
for
dew condensation prevention, Sensors 11.4 (2011): 3640-3651.
1002391 See also Shamshiri, et al, A review of greenhouse climate control and
automation systems in tropical regions, J. Agric. Sci. Appl 2.3 (2013): 176-
183., Ma,
et al, An algorithm to predict the transient moisture distribution for wall
condensation
under a steady flow field, Building and environment 67 (2013): 56-68.,
Klingshirn, et
al, Test design for condensate analysis in refrigerator vegetable drawers,
Home
Economics and Science 68 (2020) ISSN 2626-0913. DOI: 10.23782/HUW 18 _2019,
(published on March 11, 2020).
1002401 In another exemplary embodiment, a control strategy is modeled after
the
use of 'vapor pressure deficit' (VPD) as disclosed in Shamshiri, et al,
Membership
function model for defining optimality of vapor pressure deficit in closed-
field
cultivation of tomato, Ill International Conference on Agricultural and Food
Engineering 1152. 2016: "Greenhouse climate control and management begins with
accurate understanding of the crop growth environment. According to the food
and
agricultural organization (FAO, 2002) guidelines for crop evapotranspiration
(ET),
major climatic factors influencing crop growth and photosynthesis in
greenhouse
production are air temperature (7), relative humidity (rH ), and vapor
pressure deficit
(VPD), CO2 and light. Since alone cannot measure dryness of the air (ASHRAE,
2010), calculation of a more accurate indicator, VPD, is of interest. This
parameter
can be used to estimate ET, and is defined as the difference between
saturation vapor
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pressure (VPsat) and actual vapor pressure (VP,,,,) at a known T and rH.
VPD
provides a better indication of the evaporation potential than rH and is
capable of
better reflecting how plant feels. It can be used to predict how close a plant
production
environment is to saturation in order to avoid condensation problems. ... In
tropical
lowland environments (Shamshiri and Ismail., 2013 and Ismail et al., 2015), a
high rH
of the greenhouse air leads to condensation dripping from the cover, causing
fungal
spores besides appearing mineral deficiencies due to low sap movement in the
plant.
Pathogens develop and infect plants in these environments. Prenger and Ling,
(2011)
recommended that the VPD of greenhouse air should be kept above 0.20 kPa. The
optimal values according to this reference are reported in the range of 0.5 to
1.0 kPa.
... Fungal pathogens and mineral deficiency symptoms appear below VPD value of
0.43 kPa. Disease infection can be most damaging below VPD value of 0.2 kPa."
1002411 In exemplary embodiments of the instant invention, the VPD control
approach is used to model the vapor pressure deficit of the target food item
to reflect
the risk of microbial growth resulting from the dry fog during the UVC
treatment.
Note that additional testing is required for accurate modeling given that the
UVC dry
fog scattering time periods are much shorter than growth cycle of plants.
1002421 Additional modelling for use in control strategies in the instant
invention
can be found in prediction of moisture content in grain silos. "After
harvesting, grain
is normally stored for a period of time. To maintain grain quality during
storage,
grain must be protected from the growth and reproduction of insects, mites and
fungi
[1,2]. Storage temperatures lower than 15 C can prevent insect development
[3,4].
Therefore, temperature is one of the most important thermodynamic variables in
storage that determine stored grain quality and their commercial value [5].
The
aeration is an effective and economical way to improve storage conditions
[4,6]. It is
used to remove some of the heat accumulated and the excess of moisture
produced
by respiration of grains [5,7]. The process of respiration continues during
storage for
a long period, and the interaction between air humidity and temperature is
important
[8]. When the moisture of stored grain is more than 15%, grain respires faster
than
dry grain and forms hot areas that are favourable for fungal growth and insect
attacks. Many studies have been conducted to predict the temperature and
moisture
content variation in conventional storage system [9-12]. Mathematical model of
convective drying of wheat is reported by Aregba et al. [13]. A coupled heat
and
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mass transfer model is used by Hemi s et al. [14] to predict drying
characteristics of
wheat under convective air drying ... A mathematical model based on heat and
mass
balances was developed. The grain temperature and moisture content are of
major
importance to preserve a safe storage of wheat under critical climatic
conditions.",
Hammami, et al, Modelling and simulation of heat exchanae and moisture content
in
a cereal storage silo, Mathematical and Computer Modelling of Dynamical
Systems
22.3 (2016): 207-220. Drying methods for the instant invention are also
discussed,
e.g., in Design And Construction Of A Tunel Dryer For Food Crops Drying and
Energy-efficient Industrial Dryers of Berries.
[002431 Of course, the sorption properties of grains as described above is
different
than that of many other foods. Further support for modelling a variety of
foods is
understood by examining the difference in the sorption properties of different
food
items, e.g., as described in Lind, et al, Sorption isotherms of mixed minced
meat.
dough. and bread crust, Journal of Food Engineering 14.4 (1991): 303-315, "The
equilibrium water content and the water activity of a foodstuff at a given
temperature
and pressure are related by the sorption isotherm. When a food is exposed to
an
atmosphere of a given relative humidity and temperature, it can be deduced
from the
sorption isotherm whether water will evaporate or be absorbed at the surface.
Szuhnayer (1973) discussed the use of the sorption isotherm to calculate the
moisture
exchange between the air and the food, and between foods with different
sorption
characteristics. If the driving force for mass transfer at the product surface
is assumed
to be the difference in partial vapour pressure of water between the surface
of the
food and the air, the sorption isotherm can be used in the calculation of mass
transfer
rates. The sorption isotherms determined during desorption and adsorption,
respectively, often differ, showing a hysteresis effect. The hysteresis effect
of non-
mixed meat is small. Additives, such as salt, may strongly affect the sorption
isotherm and may cause hysteresis (Lioutas et al., 1984). The content of other
constituents, such as starch and fat, can also affect the sorption behaviour
(Motarjemi, 1988). The sorption isotherm is affected by the temperature at
which it is
determined, and in general the hygroscopicity decreases when the temperature
is
increased (Labuza, 1968; Loncin & Weisser, 1977). The sorption isotherm can be
determined either gravimetrically or by measuring the water activity at
different
water contents of the food. The gravimetric determination means that the water
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content of the sample is brought into equilibrium in an atmosphere of a
certain
relative humidity, and that the loss or uptake of water is measured by
weighing the
sample. ... Meat - The time to reach equilibrium was 3 weeks and mould was not
detected by visual inspection, except at the highest humidity at 20C, where a
small
5 amount of mould was found at the time of the final weighing. ... Dough -
The
equilibrium time for dough was 4 weeks at 6 C and 3 weeks at 30 C. At 6"C, a
very
small amount of mould was seen at the highest humidity at the last weighing.
...
Crust - The moisture equilibrium of the crusts was reached within 17 days at
30 C
and within 14 days at 90 C."
10 1002441 The kinetic (temporal) equation for moisture relates to the
sorption
isotherms of the food product, the temperature and RH: "Changes in grain
moisture
and temperature of stored wheat were investigated for three different relative
humidities. These experiments aimed to determine influence of low relative
humidity
aeration on the wheat moisture content. in summer, the average ambient
temperature
15 is about 30 C. This temperature will be operated to cool the stored
wheat mass.
Wheat temperature is varying between 32 C and 42.9 C and the inlet air
relative
humidity of 40%, 50% and 60% Results indicate the significant influence of
blown
air dehumidification on decreasing relative humidity of interstitial air and
wheat
moisture content. ... Microorganisms are unable to multiply when interstitial
air
20 relative humidity is below 65% [4]. For that reason, the preservation of
wheat quality
is related to the safe moisture content of the grain. Low-cost aeration
systems have
therefore the potential to provide the necessary flexibility for temporarily
grain
storing and cooling [3]. Some authors have developed and validated
mathematical
models to predict mass and heat transfer of stored grain during the aeration
process
25 [4, 5, 6, 7]. Few studies have focused on the use of dehumidifier during
the aeration
process of stored grain and the impact of this method on the grain's moisture
and the
product quality [7, 8]. Reference [9] reported the potential using of low
temperature
and low relative humidity RH to dry rough rice without affecting product
quality and
showed that drying duration can be shortened by reducing the RH. ... The
modified
30 Henderson equation (2) was used to predict equilibrium moisture content
for
temperature of 30 C and at different relative humidity (40%, 50% and 60%). ...
The
air-grain mass transfer is described by a kinetic equation [3, 7]. The
reduction of
grain moisture content until safe level of storage involves simultaneously
heat and
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mass transfer processes, which can change grain quality. ... Equilibrium
relative
humidity was predicted using wheat sorption isotherms. For 12% and 14% wet
basis
initial moisture content, safe storage conditions equilibrium RH < 70% hold
from
summer to winter [11]. " Hammami, et al, Influence of relative
humidity on
chan_es in stored wheat moisture and tern = erature, Journees Tunisiennes des
Ecoulements et Transferts- JTET2016, Hammamet ¨ Tunisie, December.
1002451 A further dive into the physics of moisture migration into foods
relates to
the diffusion of the fog environment (gaseous water vapor and liquid
condensate)
into solids vs. exposure time as discussed, e.g., in Diffusion of water in
food
materials - a literature review. "Central to understanding the effect of
moisture on
interfacial adhesion is to first identify the rate at which moisture is
delivered to the
interface. The three primary parameters that have the greatest effect on
diffusion
rates are the size of the diffusing particles, temperature, and viscosity of
the
environment. ... and increase in temperature will produce a higher kinetic
energy
yielding an increase in velocity, thus particles will diffuse more rapidly at
elevated
temperatures." The Effect of Moisture on the Adhesion and Fracture of
Interfaces in
Microelectronic Packaging
1002461 Thus, increases and decreases of food moisture content can be
predicted
via mathematical models as described above. Interstitial spacing between food
items, the thermal environment of the UV tunnel, RH, the initial moisture
content of
the food items, and any subsequent fog-evacuation/drying must also be
incorporated
into the model after correlating with actual measurements. Ultimately, this
will
inform the process engineers the degree to which moisture will enter the food
during
the process under different ambient (T, RH) conditions, and if the moisture
must be
removed post UVC dry fog scattering treatment, and the possible moisture
removal
rates based on kinetic modeling of the removal process to inform factory
production
rates and whether there are any resultant negative effects on food quality.
1002471 Testing can be performed via actual food products, but also via
surrogates/proxies whose sorption and transpiration are similar to the actual
food
product(s). In fact, the proxies can be used as sensors much like the wireless
U VC
dosage pucks that are used in UV tunnels. As a rough example, a sponge can be
fitted
with moisture/rH/T sensors to inform the control system as bread runs through
a UV
tunnel in order to minimize the risks of pathogenic microbial growth (and to
set
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alarms if exceeding the control authority). After passing through the UV
tunnel, the
sponge can be heated to adjust moisture content of bread as it enters the UV
tunnel,
and to expel moisture so that it can be used again in the UV tunnel. In a
preferred
embodiment, a generic surrogate is used that can be adjusted depending upon
the
food product.
1002481 A surrogate can be created by adjusting the compression/decompression
of a piece of foam so that its sorption/desorption can be varied as disclosed
in Glenn,
et al, Sorption and vapor transmission properties of uncompressed and
compressed
microcellular starch foam, Journal of agricultural and food chemistry 50.24
(2002):
7100-7104.
1002491 Other surrogates/proxy arrangements can be devised to mimic the
sorption effects of variable porosity, e.g., via variable apertures between
chambers.
To avoid microbial growth in the surrogate/proxy device (important for
reusable
devices), the arrangement should be fabricated, at least in part, of UV
transmissive
material such as FEP/UVGFS such that the UVC rays in a UV tunnel can penetrate
the device so that it is continually disinfected as it passes through the UV
tunnel.
Note that the surrogates/proxies can utilize sensors that change their
electrical
properties, chromatic properties, or other to indicate moisture content of
food
products (or non-food products) that are treated with UVC dry fog scattering,
be it a
UV tunnel, an enclosed disinfection box, or the like.
1002501 When considering the injection of dry fog, e.g., into
a UV tunnel, one
must consider fixed/variable fog dispersal manifolds and spray bars, e.g., in
UV
tunnels with reference to those used with dry fog in dust suppression as shown
in
Fugitive Dust Control Using "UltraFine Fog". Headers and manifolds for
distributing
the dry fog and supplying nozzles are discussed, e.g., in Considerations in
Selection of
Fogging Systems (Armstrong International, Three Rivers, Michigan) and
US5893520
Ultra-dry fog box.
1002511 In order to achieve a desired amount of scattering, it is important
that the
thickness and number concentration of the dry fog are appropriate between a
target
surface and the UVC rays from the light source(s). Optical ray tracing
simulation
software such as TracePro (Lambda Research Corporation, Littleton, MA) that
account for bulk scattering can be used to optimize the fog thickness and
concentration for a given reactor geometry (fog chamber and UVC
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absorbance/transmittance/reflectance/scatter of surfaces, light source
locations and ray
angles) in order to optimize the fluence at surface portions of a target for a
given
application. CFD and multiphysics simulation software are also viable options.
1002521 Figure 24 is a snapshot of a custom simulation constructed to
understand
how fog concentrations change in space both axially and radially, when
directed
laterally in the air using CFD. The example shown is for a very low
concentration,
using the following conditions: Operating Temperature=25 C, Operating
Pressure=latm, Air properties (assumed RH 100%, fully saturated): Density,
pa=1.17kg/m 3, Dynamic viscosity, it', = 1.86x10-5kg/m-s, Velocity, vu=0.5m/s.
Water
Droplet properties: Density, p. =997kg/m 3, Dynamic viscosity, p. = 0.001kg/m-
s,
Diameter, (1= 3.8xlem, Concentration = 10 droplets/cm3, Velocity, vw=0.5m/s,
Mass flow rate (hand-calculated) = 2.39x10-1 kg/s. Static Pressure=pg(z0-z)
(where
g=9.81m/s2). The figure shows the concentrations at 25%, 50% and 75% of the
distance between the pipe exit and the opposing wall (no crosswinds).
1002531 This type of spatial/temporal plot is especially instructive for
applications
where the UVC dry fog scattering system is moving. It indicates the expected
number
concentrations at various distances for a given fog concentration and exit
velocity. It
thus provides feedback to the designer as to what can be expected, and the
adjustments necessary to reach required design specifications (when correlated
to
actual measurements), which include the suitable distances over which the
concentration is viable for the scattering performance when combined with the
light
source geometry. Further CFD analyses can then be run with crosswinds that are
to be
expected based, e.g., on site-surveys. Note that crosswinds can be considered
as fluid
motion of the medium adjacent to the scattering field. Abatement of crosswinds
include wind breakers, like the tent coverings (which is just another type of
UV
tunnel, and conversely, factory conveyor-type UV tunnels can/do function as
wind
breakers) used in the new nighttime mobile UVC disinfection of crops as
described in
A shot in the dark - Nighttime applications of ultraviolet light show promise
for
powdery mildew control.
1002541 In one embodiment, dry fog is (optionally chilled) and injected below
a
UVC transparent FEP film that is suspended just above strawberry plants in a
field.
The film can be planar (parallel to the ground), curved, or in any other shape
that
maximizes system efficacy. The film resides within a tent or tunnel that is
pulled
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behind a tractor as discussed herein, within which resides an array of UVC
lamps with
their light directed at the plants. The film helps to prevent the fog from
dispersing,
especially in response to ambient winds and pressure changes. This enables the
fog to
be at a therapeutic concentration. In one embodiment, fog is injected onto the
plants at
the front of the tent/tunnel if the evaporation rate is low enough to maintain
the
therapeutic concentration at the speed the tent/tunnel is being pulled at. In
another
embodiment, fog is injected along both sides of the plants. Note that multiple
FEP
films can be employed to generate different strata of scattering fields to
enhance
efficacy. For example, in one embodiment, higher concentrations may be
desirous on
the sides of the plants than the tops of the plants. One film can be shaped to
corral the
fog with thicker fog sections along the side of the plants than on the top. In
another
embodiment, different FEP films are used to trap fog fields of different
concentrations
¨ to satisfy a desired spatial profile of scattering vs homogenization.
Alternatively,
one strata layer is empty with fog added only when the adaptive system demands
additional scattering/homogenization, after which it is evacuated. In yet
another
alternative, one film is used, and one strata layer is formed below the FEP
film, and
another above the FEP film, as needed
1002551 The tent structure can also be fitted with skirts and baffles to
minimize the
effects of cross-winds and the like. Skirts (fixed and/or adjustable) that
isolate air flow
are known in the automotive/trucking industry, e.g., US8899660 Aerodynamic
skirts
for land vehicles, US10457340 Adjustable body skirting assembly and a vehicle.
Skirts are also used in hovercraft, e.g., US5560443 Hovercraft having
segmented skirt
which reduces plowing and other flexible/segmented skirts in US Class
B60V1/16.
Lightweight and flexible/segmented skirts in the instant invention also help
in
avoiding damage to the plants. Air curtains, brush seals, and vinyl strips, as
discussed
herein, are also contemplated for use around the exterior of the tent/tunnel
to aid in
isolating the fog from the external environment. In one embodiment, a cape-
like cover
is dragged over the plants behind the tent/tunnel to further prevent air
entering/leaving
the tent at high enough velocities to materially affect the fog distribution
such that
there isn't sufficient authority in the adaptive system to compensate. A
similar cover
can be dragged atop the plants by the tractor in front of the tent/tunnel.
1002561 The skirting above can be considered akin to wind baffles that are
used in
HVAC systems, e.g., US20210063029 Wind baffle with multiple, variable air
vents
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for an air-conditioner, in heating devices, e.g., US6125838 Gas grill with
internal
baffles for use in high wind conditions, US4893609 Wind-resistant outdoor
heating
appliance, US7252503 Wind-proof venturi tube. In one embodiment, such baffles
are
deployed within the tent/tunnel to break up air currents and are made out of
UVC
5 transmissive FEP or highly reflective PTFE in order to minimize UVC
absorption. In
another embodiment, baffles are placed around the outside shape of the tent to
spoil
the flow of incoming wind and redirect it away from the interior of the
tent/tunnel.
Also see Fig. 1 of the '071 application, which shows a cart structure which
directs
radiation away from the cart to vines on either side.
10 1002571 In one set of embodiments, scatterometers (in combination with
wind &
pressure sensors) are deployed to test for effects of wind and pressure on the
concentration and uniformity of the fog field and adjust the deployment of fog
(and
skirts/baffles) in an adaptive fashion. For example, a variable speed
fan/blower is used
in an embodiment to direct the fog away from the piezoelectric elements into
the
15 desired fog field location. Slower speeds will allow more fog to
evaporate and drop
back into the source water pool, thus lowering Nd. Many other ways of changing
Nd
are contemplated, such as partially closing a gate valve that feeds a mixing
box which
then feeds a manifold. Alternatively, a percentage of solenoid valves at the
manifold
exit holes can be opened. In any arrangement, care must be taken to ensure the
proper
20 mixing of the fog (to ensure homogenization around the target objects)
and speed of
the fog (also effects homogenization as well as evaporation and coagulation).
Finally,
as mentioned herein, (fluorescent) tracer particles are used in the
agricultural industry
to track how (disinfectant) fog fields move after (crop duster) deployment in
the field.
Such tracers are contemplated for use with the instant invention.
25 1002581 Collection and distribution of dry fog - In an exemplary
embodiment, dry
fog is first collected in a box and then uniformly distributed as shown, e.g.,
using a
manifold, a mesh filter for trapping larger droplets, and a box with a drain
as in
US5893520 ('520) Ultra-dry fog box. The dry fog can be generated by any of the
disclosures cited herein and the associated patent applications. The slotted
output
30 disclosed in the '520 can be used to lay down a layer of dry fog across
fruits and
vegetables as they enter a UVC tunnel. The placement of dry fog can be
considered
the task of a 'director', i.e., directing the dry fog (or scatterers in the
generic sense)
into the desired location(s). The director can be anything from an ultrasonic
atomizer
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whose natural exit flow is placed in a predefined location, or an open-ended
pipe from
an atomizer into a UV tunnel, or a simple connector into a box (e.g., like the
connector installed on the HomeSoap unit), or a hole in the bottom of a
manifold for
dry fog to fall in response to gravity, or any of the myriad of flow
shaping/control
geometries cited herein and the references. The scattering generator and
director can
be custom fabricated, ordered from stock items, or constructed at least in
part by
tapping into an existing system. The drain can direct the condensate into the
sewer
treatment system or back into the dry fog source water reservoir to recycle,
as
appropriate.
1002591 Previous references have been made to diffusers, including the use of
vortices to distribute the dry fog most effectively for the application.
Diffusers used in
IL VAC systems, are e.g., discussed in technical detail in Air distribution
engineering
guide (Price Industries, Inc., Suwanee, GA) describing terms of art such as
air pattern,
throw, drop, and spread, as well as registers, grills, louvers, etc. A simple
application
would be the placement of an air distribution device on the output of dry fog
bulkhead
connectors of the instant application in order to achieve a desired
concentration
profile Of course, one must be mindful of the effects of using such as device,
e g ,
increased pressure drop, backpressure effects on the efficacy of the fog
generator,
droplet coalescence due to impingement, creation of concentration
spatial/temporal
non-uniformities, incremental evaporation and changes in droplet size due to
increased droplet airspeed as cited, e.g., in How far droplets can move in
indoor
environments ¨ revisiting the Wells evaporation¨falling curve. Other technical
analyses of diffusers are described, e.g., in Experimental Study of Vortex
Diffusers,
Simplified Numerical Models for Complex Air Supply Diffusers, Air flow
characteristics of a room with air vortex diffuser, A simplified approach to
describe
complex diffusers in displacement ventilation for CFD simulations.
1002601 Dry fog retention with a UVC tunnel or the like -
1002611 a) Dry fog can be trapped between one or more UVC transparent sheet
members (FEP, UV grade fused silica and the like), within which a conveyor
belt
operates. One member may be sufficient if the conveyor belt is solid and does
not
allow fog to pass through. A second member may be needed below the conveyor
belt
if the belt is porous, such as a wire link belt, which are used in some
instances to
irradiate the foodstuffs from the bottom as well as from the top (and sides).
The sheet
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member(s) that contain the fog also aid in keeping the relative humidity at a
high level
to minimize dry fog evaporation. The dry fog can be injected between the
sheet(s) and
the belt at one or more locations along the path of the conveyor belt, as
necessary to
maintain the desired level of UV scattering to optimize the dosage. It may be
desirable to maintain a consistent level of dry fog concentration along the
length of
the conveyor belt, but that need not be desirable for all applications. For
some
applications, it may be beneficial to have low/no scattering for a portion of
the travel
through the tunnel to maximize the dosage to certain surfaces. For some
applications,
testing may reveal that the fog is best created in multiple sections along the
belt
separated from each other. For example, a product turning device may be used
at the
half-way point to rotate the product for better UVC surface coverage, and so
fog
would be injected on either side of the turning device (perhaps with little or
no fog
before entering/leaving the turning device). Of course, the height of the
sheet member
above the conveyor must allow passage of the products.
1002621 b) Dry fog height span must accommodate differences in product sizes.
For example, a strawberry may be one or two inches tall, whereas a loaf of
bread may
be four of five inches tall liluewater Technologies Group, Inc. (Wixom, MT)
makes
UVC sanitization tunnels that accommodate up to 30 shopping carts. Therefore,
in
order to achieve the proper UVC dosage, scattering fog fields (in conjunction
with the
coupled UVC source) of the instant invention are contemplated to be sized
accordingly, whether to envelop an entire product and/or irradiate the product
in
sections.
1002631 c) In an exemplary embodiment, a UV tunnel irradiates strawberries by
filling a UVC tunnel with a sufficient flow rate of dry fog to create a six
inch
thickness dry fog field, half above a wire-link conveyor belt and half below.
The fog
field is kept from sinking further than three inches below the belt by a
transparent UV
grade fused silica (UVGFS) plate, below which are UVC light sources directing
rays
to scatter up through the fog field and through the wire-link belt onto the
strawberries.
The UVGFS plate(s) are slightly angled to allow any condensate to run off into
a
drainage system. In this embodiment, no plate is placed above the three inch
thickness
of fog extending above the wire-link belt. The UVC tunnel has sidewalls (or
optionally the belt is configured with vertical compartments) that prevents
the fog
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field from spilling over the sides and on to the floor. A vacuum system is
placed after
the tunnel exit to remove any residual moisture.
1002641 d) In the next exemplary embodiment, modeled after the previous one
for
strawberries, the dry fog flow-rate is high enough such that no lower UVGFS
plate
would be necessary, =with the fog field continuously dropping vertically
through the
tunnel as shown in Fig. 1 and described below:
1002651 i) Referring now to Figure 1, a UVC tunnel 3700 comprises a wire-link
belt, above and below which are UVC lamps directed at strawberries supported
by the
top of the belt, each lamp surrounded by a highly UVC-reflective aluminum
(e.g.,
4400UVC MIRO 4 from ALANOD GmbH & Co. KG, Ennepetal, Germany) cusp
reflector. See, e.g., the discussion of cusp-reflectors in US7195374
Luminaires for
artificial lighting including Fig. 3 therein, and US6948832 Luminaire device
including Fig. 10 therein, and in both the applicant is a cited inventor. The
'374 cites
the need for the cusp reflector: "U.S. Pat. No. 4,641,315, "Modified Involute
Flashlamp Reflector", granted on Feb. 3, 1987 and assigned to The Boeing
Company.
This patent discloses a set of parametric equations that can be used to define
the shape
of cusp reflectors that project light emitted by tubular cylindrical lamps
without
directing any reflected light back to the cylindrical surface of lamp
envelopes.
Avoiding back-reflections to the lamp reduces light absorption by the lamp.
Accordingly, this improves efficiency by increasing the amount of light flux
projected
out from a cusp reflector/lamp fixture for a given electrical power input."
The '832
also shows the use of a cusp reflector with an integrated collimator
structure, useful
for the instant invention. Note that the lamps can also be partially
surrounded by other
high efficiency reflector arrangements as is known in the art instead of the
cusp
reflectors shown in Fig. 1 of the instant invention. In some instances, a
combination
of two reflectors (e.g., a specular reflector backing a diffuse reflector) are
useful in
providing high efficacy and a suitable degree of homogenization, see, e.g.,
W01995002785A1 Backlight apparatus with increased reflectance. For UVC
systems, a diffuse reflector suitable for use in UVC systems is from Porex
Corporation (Fairbum, GA), see Ultraviolet Reflectance of Microporous PTFE.
Note
that UVC LEDs project only in the forward direction, obviating the need for a
cusp
reflector.
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1002661 ii) The UVC lamp/reflector assemblies are optionally sealed to a UV
grade
fused silica (UVGFS) window (for ease of cleaning and to avoid any warranty
issues
regarding lamp/reflector exposure to diy fog). The window is spaced from the
center
of the average strawberry height based on simulation and then optimized
further in-
situ, based on dosimetric measurements of real strawberries/products using
applicable
pathogens (and/or use of the dosimetric avatars as cited herein), dry fog flow
rates
(whether from a nebulizer array or a piezo array, or other), the number of
lamps (their
power, the reflector geometry, etc.), the conveyor belt speed,
temperature/humidity
inside and outside of the UVC tunnel, etc. Note that UVC lamps can be placed
closer
to irradiation targets under dry fog conditions since the dry fog scattering
will tend to
eliminate the high intensity hot spots that maybe detrimental in a no-fog
condition
since the dry fog acts like an optical homogenizer for the UVC field and thus
lowers
the hot spots. An exemplary application includes the use of dry fog scattering
of UVC
to prevent the overheating of fish fillets as described in traditional pulsed
UVC
treatment in Inactivation of Escherichia coli 0157 117 and Li steri a
monocytogenes
inoculated on raw salmon fillets by pulsed UV-light treatment and Intense
light pulses
decontamination of minimally processed vegetables and their shelf-life.
1002671 (1) The UVC tunnel entrance and exit doors are designed to minimize
the
leakage of dry fog outside the system. Such doors are designed to avoid
product
damage and meet the necessary product flow rate through the tunnel. Non-
limiting
exemplary door technologies are cited herein, e.g., vinyl strip like curtain
doors or
automated mechanical doors fabricated from (or covered with) UVC- and food-
compatible materials. Note also that air curtains can be considered as
previously cited.
A slight negative pressure inside the tunnel can also be considered to contain
the dry
fog, so long as the relative humidity is maintained within the tunnel at
sufficiently
high levels to minimize dry fog evaporation, and its impact on the ambient air
surrounding the tunnel is also considered. Test data will be shown herein that
a tight
seal of the fog within the irradiation chamber may not provide much benefit
when
compared with a slightly leaky seal.
1002681 (2) An exhaust/vacuum hood or the like is positioned outside the exit
door
in order to remove residual fog and excess moisture from the exiting product
and from
any leakage through the door. Note, however, for some products, e.g., salmon
fillets,
moisture removal may not be needed (or as complete) as in other products,
e.g., bread.
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A similar vacuum hood may be placed near the entrance door (or above the
entire
system including both the entrance and exit) to capture dry fog leakage and
maintain
the desired relative humidity in the area of the tunnel and/or without overly
taxing the
existing HVAC system. Sensors can be used as known in the art to run the
motorized
5 exhaust at only the necessary power level to meet the requirements,
thereby
minimizing energy costs (and audible noise). See, e.g., VHB Series Type II
exhaust
hoods (used for condensation or heat removal applications, not grease laden
vapor)
from CaptiveAire (Raleigh, NC), which can be coupled to one of their air
movers
specified for the airflow as determined by CFD and verified through testing.
Note that
10 the exhaust/vacuum system need not vent outside of the facility as the
fog can be
condensed, collected, and routed to the sewer system or recycled as
appropriate.
Incremental increases in relative humidity can be treated with a dehumidifier
or via
the building's HVAC system.
1002691 (3) The dry fog is generated by 1.7 MHz piezoelectric ultrasonic
15 transducers in a dry fog atomizer selected, e.g., from the SM-xxB
product line
manufactured by Jiangsu Shimei Electric Manufacturing Co., Ltd. (Jiangsu
Province,
China), where `xx' defines the wattage, in hundreds of watts, in seven
different
models from 300 watts to 3200 watts. Based on the desired UVC tunnel size and
product flow rate, the appropriate aerosol generated model is chosen, where
higher
20 wattage generates a higher flow rate of aerosol. The units consume water
from plastic
jugs or can be plumbed into a domestic water system. The water quality should
be
food grade, and the mineral content of the water can be adjusted to meet the
dry fog
generation needs as discussed elsewhere herein, as minerals can affect dry fog
particle
size and evaporation rates, as well as deposits of scale that build up over
time,
25 potentially clogging the manifold ports, reducing interior UVC
reflectance, and
narrowing the gaps between wire-links to name a few. Distilled and deionized
water
are also options as discussed in the related applications of the instant
invention. The
dry fog generators feed up to three 110mm output ports, which are connected to
one
or more manifolds within the UVC tunnel. The number concentration can be
varied
30 by adjusting the wattage and/or diluting the output (e.g., feeding-back
some of the
output directly back into the source water without using it in the irradiation
chamber).
1002701 (4) The combined lengths of pipe that deliver the dry fog to the
treatment
zone in the UVC tunnel must be considered, since condensation could occur,
leaving
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less dry fog for distribution. An analogous situation is found in dry fog
nebulizers
used for patients. See, e.g., In-vitro Comparison of 4 Large-Volume Nebulizers
in 8
Hours of Continuous Nebulization, "We studied 6 units of the following
nebulizer
brands: AirLife Misty Finity (Cardinal Health), Flo-Mist (Smith's Medical),
Heart
(WestMed), and Hope (B&B Medical Technologies). All the nebulizers were
operated
according to the manufacturers' recommendations and connected to 180- cm of
flexible corrugated tubing. ... Raabe et al reported delivery efficiency to
the mask of
about 90% with the Heart nebulizer.11 In the present study the efficiency was
only
77%. We speculate that that difference is due to the difference in tubing
length in the
studies (30 cm vs 180 cm) and the difference in testing time (5 min vs 60 min
and
hourly for 8 h). Also, they applied continuous suction at 17 L/min, whereas we
had no
flow interacting with the nebulizer output." Now a 180 cm long tube is 70"
long. As a
data point, the GermAwayUY Sanitation Conveyor System (SPDI UV, Delray Beach,
FL) specifies that their UVC tunnel has a "UV Germicidal Area" of 40"x20", and
so
if the dry fog manifold was also 40", that leaves 30" for plumbing the SM-xxB
dry
fog generator to the manifbld in order to equal the 70" tubing length in the
nebulizer
study cited above Note that the dry fog falling distance though the INC tunnel
treatment zone is comparable to the dry fog travel distance into a person's
body to the
bottom of their lungs and both systems exhibit high humidity in these regions,
so
again, the systems are somewhat analogous when considering dry fog
evaporation. In
addition, the lung temperature is elevated above ambient, as is the interior
of a UVC
tunnel due to the heat generated by the UVC lamps. Dry fog evaporation and
condensation in the dry fog distribution system in the instant invention can
be
minimized by careful temperature/RH control (and/or additives to water) as
cited
elsewhere in the instant application (including all family member
applications). Note
that hose/pipe bends can form traps that act like the traps that plumber's
install below
a sink. These traps can collect water (which could lead to pathogen breeding)
and
increase the pressure drop due to the pipe restriction.
1002711 (5) In this exemplary embodiment, the manifold is comprised of a 4" ID
type 304L stainless steel pipe (a food-safe material that can withstand UVC
irradiation) that extends along the length of the tunnel, with ports on both
sides of the
pipe extending along the pipe length, high enough up the side of the pipe to
allow
condensate to collect in the bottom of the pipe and run towards the distal end
of the
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pipe (the pipe is slightly tilted at about 'A" per foot like in pipe drain
lines) outside the
UVC tunnel and drain into either the sewer system or plumbed back to the
aerosol
generator for reuse (as appropriate in light of applicable plumbing codes and
best.
practices). To minimize cost (solid 304L pipe is expensive), given that the
pressure in
a dry fog system is near that of ambient air, the pipe can be made from 304L
sheet
metal formed into a cylinder, with an overlapping seam that is riveted and
sealed from
dry fog leakage with UVC- and food-compatible 304 stainless steel tape
available,
e.g., from Viadon LLC (Peotone, IL). The pipe is placed in the tunnel with the
seam
facing upwards to minimize the risk of condensate leakage, with holes punched
or
laser cut along each side for distributing the dry fog down through the
tunnel. The
hole sizes and spacing can be determined via CFD and verified/optimized via
testing
in the actual chamber under the normal range of operating conditions
(different belt
speeds, etc.). See, e.g., the use of CFD and related analyses in Simulation of
UV-C
Dose Distribution and Inactivation of Mold Spore on Strawberries in a Conveyor
System, and Computational fluid dynamics as a technique for the UV-C light
dose
determination in horticultural products. The input end of the fabricated pipe
is
connected outside the tunnel to low cost pipe and fittings compatible with
potable
water (see, e.g., NSF/ANSI 61: Drinking Water System Components ¨ Health
Effects). Care must be used to avoid UVC light piping (e.g., through the holes
in the
manifold) and light leakage outside the UVC tunnel, which can be harmful to
people
and to incompatible materials. Ultimately this must be measured with UVC
radiometers to guide any appropriate remediation, e.g., the use of baffles to
make the
UVC follow a more tortious path in exiting the tunnel, thereby increasing the
loss of
intensity with each extra bounce. Of course, the methods chosen should also be
chosen to minimize standing water (and shadows) that promotes pathogen growth.
The fabrication of the dry fog (and other) features, whether retrofit or
forward-fit,
must also be compatible with the applicable UVC tunnel cleaning processes
(chemicals, temperatures, pressure washers, etc.). Note that the pipe can be
covered
with UVC reflective material such as Virteke Reflective PTFE (Porex
Corporation,
Fairburn, GA), and ray trace software such as TracePro (Lambda Research
Corporation, Littleton, MA) can aid in determining optimal geometries to
maximize
coupling of UVC from the lamps to the scattering fog to the product. The 4" ID
tube
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may also be distributed to smaller ID plenums between the lamps located at the
top of
the tunnel.
1002721 (6) In a slightly different embodiment, the manifold is a box built
above
the top of the UVC tunnel, covering about the same area, with holes drilled in
the
locations between UVC lamps up through the top of the tunnel and into the
manifold
box. As before, exact locations and hole sizes are determined by CFD with
verification via dosimetric testing at various locations on the conveyor belt.
The dry
fog is then plumbed between the aerosol generator and the manifold. The box
also has
a drain that allows any condensate to be captured and run to the sewer or
recycled as
before. The heat from the lamps must be considered as it can lead to
evaporation
which can then lead to condensation at saturation, after which the droplet
sizes
change, see, e.g., The Effect of Relative Humidity on Dropwi se Condensation
Dynamics. Changes in droplet size distribution will change the scattering
profile and
can also lead to wetting-sized droplets that would not be suitable for certain
products
passing through the UVC tunnel, e.g., bread. The perforations in the top of
the UVC
tunnel can be fitted with insulated tubing to minimize dry fog evaporation in
the
higher temperatures of the tunnel near the top due to heat rise One or more
tunnel
walls can be fitted with heat exchangers to minimize the temperature in the
chamber.
The manifold box can be thermally isolated from the top of the UVC tunnel by
insulative material; see, e.g., such materials from McMaster-Carr (Aurora,
OH).
Alternatively, a heat exchanger can be placed between the bottom of the
manifold box
and the top of the tunnel, such that ambient (or cooled) air is directed
therebetween
via one or more fans. In either case, tubing is installed at periodic
locations in the
manifold box (and between lamp locations in the tunnel) to carry the fog
between the
bottom of the box and the discharge points in the tunnel.
1002731 (7) In yet another embodiment, the fog is injected from ports at the
entrance and exit surfaces and directed inside the tunnel. This is especially
efficient in
retrofit applications.
1002741 (8) In still another embodiment, the fog is shaped/positioned to
envelop the
product with a specific thickness/concentration to generate a desired
scattering
profile. The fog can be shaped in numerous ways, e.g., one or more of (a)
chill the
water and/or resultant fog to cause it to sink, (b) use air pressure/velocity
and an array
of nozzles to direct the fog, where the air pressure/velocity can vary from
nozzle to
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nozzle, and the nozzles in the array can be different sizes and have different
dispersal
patterns (c) use UVC walls (transparent or reflective depending upon the lamp
arrangements) around the product (e.g., forming a container, which may be
opened on
one or more of top/bottom/side and/or contain support elements to elevate the
base of
the product) to contain the fog at a specified distance from the product,
where the
walls can also be shaped to maintain a specified fog thickness around the
product
and/or the walls can be the windows of the UV lamps that can positioned at
various
distances and angles relative to the product (d) introduce more laminar flow,
(e)
introduce more turbulence., (f) use one or more of Taylor vortices, Karmen
vortices,
Vortex/smoke rings, swirl flow like in cyclones/tornados, the Coanda effect,
the
Magnus effect, the Dean effect, continuous and/or pulsed jets, and/or other
flow
effects, whether created based on the geometry and/or movement of a single
product
or a geometrically arranged group of products, and/or with the assistance of
other
stationary/moving objects, (g) introduce entire atomizers, e.g., piezo
devices, at one or
more locations inside the tunnel, each with one or more fans to selectively
direct the
fog, (h) Place a bath of water (optionally temperature controlled) below the
conveyor
belt, add pi ezo elements along the periphery in the bath to create a fog
layer above the
water that envelops the product at a desired thickness, and filter/recirculate
the water
bath, where lamps are placed above the bath, and optionally below the bath
depending
upon whether the bottom of the bath is transparent or reflective to UVC, (i)
float
products in the bath of the previous embodiment, either due to natural
buoyancy
and/or added air bubbles, and rotate the products as they proceed along a
length of the
tunnel (i.e., change their spatial orientation with respect to the source of
wave
energy), (j) drag the wire link belt through the bath where the added buoyancy
from
the water enables the products to more freely rotate, (k) rotate and/or
translate the
manifold injecting the fog inside the tunnel, e.g., by rotating/translating a
round pipe
that acts as the manifold with perforations in it, (1) insert a cylinder into
the fog
pipe/manifold, where the cylinder has geometric apertures that meter the fog
through
the apertures (or direct the fog to different nozzles in order to create
different fog
patterns for different products) in the pipe/manifold as it is
rotated/telescoped (m)
arranging products geometrically (precisely and/or with some degree of
randomness)
on a conveyor belt to distribute the fog to attain a desired scattering
profile, with or
without the assistance of other stationary/moving objects adjacent to the
products,
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e.g., like the linear spacing between tall loaves of bread or a hexagonal
pattern of'
lettuce heads (n) creating changes in fog thickness around products as they
travel
along the tunnel, e.g., traveling waves of fog via incremental deposition of
fog and/or
perturbation of the fog field using a mechanical device like a paddle or a
fluidic
5 device, like puffs of air or waves in the previously cited water bath.
1002751 Fog sinking or low-lying fog' relates to vapor buoyancy (see '806
section
42) - Note that for the instant invention, one embodiment creates the water
vapor via
an atomizer (e.g., ultrasonic) that is cooled to create a fog layer close to
the ground:
"The two main factors that affect how low or high your fog will be are the
10 temperature of the fog and the temperature of the surrounding area. ...
The cooler
your fog is, the lower it will stay. The cooler you surroundings are, the
higher your
fog will rise. ... When designing the chilling area, keep in mind that you
want to chill
your fog as much as you can ... I advise adding some obstructions for the fog,
so the
fog will have to travel around, instead of being able to go straight through
the fog
15 chiller. Basically, you want to make it stay in the chiller longer,
which will result in
colder, lower fog. .. If your fog machine has a higher wattage, you may want a
bigger exit hole This will help spread the fog and keep it low. If the exit
isn't big
enough, the fog will be forced out and will rise a few feet. ... a pretty
inexpensive fog
chiller setup with the three pieces as described above: A sealed connection
from the
20 fog machine to the entrance of the chiller. A chiller the fog must
travel around. And a
wide exit. ... Another way to help keep the fog low, if you are inside a
building or
room where you can control the temperature, turning on the heater before using
your
fog machine will help keep the fog low. The greater the contrast between the
temperature of the surroundings and the fog, the lower your fog will be." How
To Do
25 Low Lying Fog (Ground Fog) FeltMagnet.
1002761 The effects of temperature, pressure, etc. on vapor can be found e.g.,
in the
textbook Moisture of Meteorology for Scientists and Engineers (ISBN 978-0-
88865-
178-5). The physics of fog is discussed in Essentials of Meteorology - An
Invitation to
the Atmosphere, (ISBN 978-1-305-62845-8).
30 1002771 "The molar mass of water vapor is much less than that of dry
air. This
makes a moist parcel lighter than a dry parcel of the same temperature and
pressure.
This effect is known as the vapor buoyancy effect ... We define the virtual
temperature .7; = mi+r1E)1(1+r)] . . where T is temperature, r is water vapor
mixing
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ratio, and E = Mr/Md. The molar mass of water vapor /14 is 18 g/mol,
significantly
lighter than that of dry air Md, which is 29 g/mol. This makes a moist parcel
lighter
than a dry parcel of the same temperature and pressure (Emanuel 1994). Here we
refer
to this as the vapor buoyancy effect, though it is also referred to as the
virtual effect
(Yang 2018a,b)." The Incredible Lightness of Water Vapor
1002781 (9) Note that the previous elements can be changed manually, e.g., as
part
of a machine setup during a production run, and/or a computer/controller can
be used
to direct actuators to automate changes to the previous elements in
temporal/spatial
relationships to the products. Open loop and closed loop controls (or
combinations
thereof) are both contemplated.
1002791 (10) In the instant invention, low pressure (LP) UVC lamps (which are
essentially fluorescent lamps without the phosphor coating and use instead UVC
transmitting glass instead of absorbing glass) are in an enclosed UVC tunnel
(to avoid
dry fog leakage). In an analogous situation, heat exchangers have been used to
remove heat generated by high power density fluorescent backlights for
sunlight
readable liquid crystal displays (LCDs) as taught in US64934401B2 Thermal
management for a thin environmentally-sealed LCD display enclosure In the
instant
invention, UVC lamps inside the tunnel generate heat that raise the
temperature in the
tunnel. Convection currents (from air surrounding the lamps, which may or may
not
contain dry fog, depending upon whether they are isolated from the dry fog)
inside the
tunnel couple heat to the outer walls of the tunnels, which are externally
cooled like in
a heat exchanger. In one embodiment the lamps are isolated via sealed UVGFS
windows, and the ambient air inside the lamp cavity does not contain dry fog
but
filtered ambient air (to avoid contamination). In another embodiment, the
lamps are
not sealed from the dry fog, and the dry fog is cooled (either before it is
circulated in
the tunnel or via a heat exchanger inside the tunnel) such that the
temperature rise of
the dry fog does not lead to excessive evaporation and subsequent large
droplet
condensation. Thermal simulation software can aid in the design, e.g.,
Lumerical
HEAT 3D Heat Transport Solver from ANSYS, Inc. (Canonsburg, PA).
1002801 (11) In yet another embodiment, the fog is isolated from the heat
generating lamps by injecting it into the tunnel in a vertical plane between
the lamps
above the conveyor belt and the lamps below the conveyor belt. In fact, if the
conveyor belt is porous such as the wire link belt that has been cited, the
fog can be
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injected into the gap between the upper and lower runs of the belt (the belt
forms a
loop) while minimizing the blocking of UVC light with plenums, tubes, and the
like.
[00281] (12) In yet another embodiment, a UV tunnel irradiates shopping carts.
Aerosol generator discharge ports are positioned around the shopping cart. The
center
of the cart therefore receives a very dry fog concentration, however, in one
embodiment, the concentration in certain locations (e.g., between the shopping
cart
and the tunnel wall, not in the path of direct light from the lamp to the
cart) is so high
that the UV rays are redirected back towards the UV source(s) as shown in the
Monte
Carlo simulation results herein. Since the dry fog droplets essentially do not
absorb
UVC, the reflection is extremely efficient. Lower concentration fog between
the UVC
source(s) and the center of the cart are sufficient to efficiently scatter the
UVC onto
surfaces in shadow.
[002821 (13) In another embodiment, a dry fog scanner is constructed,
creating,
e.g., a six inch wide wall of fog that is passed over lettuce, such that the
fog wall is
irradiated from both sides, where the light rays from each side travel through
about 3"
of fog thickness, which has been shown herein to be an optimal scattering
thickness
for the I-WART nebulizer-style dry fog generator. Other thicknesses are
optimized
for other atomizers generating a different droplet distribution and number
concentration.
1002831 Simulations of dry fog scattering ¨ Monte Carlo simulations shown in
Figures 3 and 4 were run using Mont Carl. Rays from a pencil-like collimated
laser
beam are directed through a fog thickness of tFOG. Rays are shown scattered at
the
inclination angle, 0, in the R-z plane. The scattered rays are equally likely
to be at
any azimuthal angle, 9, around the z-axis, so only the inclination angle, 0,
of rays in
the R-z plane are shown. Collimated rays are helpful to use as an input to
better
understand the scattering effect as it passes through the fog. This way, the
scattering
angle can be attributed solely to scatter, and not a divergent input angle
from a
diffuse light source.
[00284] Mie scattering for single droplets based on the input ray wavelength
of
X-280nm (vacuum wavelength) were compared for single 1-micron and 10-micron
water droplets (nw=1.357) in air on two tools (MiePlot and MontCarl,
attributions can
be found in Applicant's presentation), not shown. Both tools show essentially
the
same results. Broader scattering occurred for a 1 droplet compared to 101.1.
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1002851 For simulating vast numbers of water droplets, Monte Carlo scattering
can
be used as shown in Figure 3. Here a 4.85" thick cloud of dry fog at a
concentration
of 100,000/cm3 are simulated separately for droplet sizes of 1, 5, 10, and 25
microns,
each at 222nm (Far UVC, nw=1.4191) and 730nm (Far-red, nw=1.3278), with
similar
results for a given droplet size.
1002861 In Figure 4 the simulations were run at the germicidal wavelength of
254nm for 5-micron droplets. Two fog thicknesses are simulated, 3.85" and
5.85",
each at four different dry fog concentrations. The differences in these two
thicknesses have a small effect, but the differences in concentrations have a
large
effect. Also note the highlighted box. It will be shown in greater detail in
the next
slides.
[00287.1 It should be noted that the actual dry fog concentration applied to a
given
application is a function of many variables. Based on the simulations shown in
Figures 3 and 4 for the conditions that were presented (wavelength, fog
thickness,
scattering element size), number concentrations between about 105/cm3 and
107/cm3
appear to be a reasonable range to test in an attempt to optimize. In fact, as
cited
herein, the HEART O nebulizer that was tested is believed to be within these
limits
This appears to be higher than the characterization of atmospheric fog & haze
cited
herein, disclosing a range of droplet sizes from about 0.111. to 2011 in
diameter, and
droplet concentrations from about 10/cm3 to 104/cm3. Note, however, that
atmospheric fog & haze can be substantially thicker than a dry fog as proposed
herein for use in a UV tunnel, and hence the experience we have of not being
able to
see through certain fog events. Thus, for a given scattering element size, the
combination of scattering field thickness and number concentration must be
considered, which is what the Beer¨Lambert law is modeled after (to arrive at
transmittance), including the correction factors applied thereto as discussed
herein.
So, in order to roughly compare one scattering field to another, the Beer-
Lambert
equations can be used to rough-order, but each field must be accurately
described by
using the appropriate correction factors.
1002881 With reference back to Figures 3 and 4, there are traces of 1000 rays
from
dry fog scattering at various concentrations, fog thicknesses, and
wavelengths. These
renderings are helpful to get an intuitive understanding of the scattering
profiles. For
each configuration, an additional simulation was done with 1-million rays for
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statistical significance. The results of these simulations are shown in in
both linear
and polar forms detailing the relative intensities at the angle, 0, in both
the forward
(00) and backscatter (180 ) directions, and all angles in between. The %
transmitted
or forward scattered, vs the % reflected or backscattered is also supplied for
each
simulation. This provides one metric to compare scattering efficiencies,
depending
upon whether the application befits from forward scattering, backscattering,
or both.
Another metric is the angular distribution as it relates to reaching in the
shadows.
1002891 Note that MontCarl also has the ability to add velocity to the
scattering
field to simulate temporal changes. Of course, simulations of this type can
also be
performed for air bubbles in water and other combinations of substances,
phases, and
electromagnetic wavelengths.
1002901 The MontCarl results shown in Figures 12 and 13 are based on
simulations 2K rays of a 635nm laser beam with a 10 HWHM divergence based on
3.61.t diameter water droplets at concentrations between 0 and 105/mm3
(108/cm3),
with a fog thickness, tFoG=385mm (15 inches). Note how the percent
transmission
(%T) decreases with increasing concentration. For Nd= 1 08/CM 3, the ray trace
was
scaled, showing the large number of rays that only travel about 8" (203mm)
before
backscattering. In Figure 13 the concentrations vary from Ne=108/cm3 to
Nd= 109/cm3, with the ray travel decreasing with increasing concentration.
This
simulation is useful to roughly determine fog concentrations (with a 635nm
laser
beam as used herein).
1002911 Test summary ¨ testing was performed with a 635nm visible light laser
to
estimate KJ, and with HomeSoape 254nm disinfection boxes comparing the
performance of dry fog to no-fog.
1002921 Three dry fog atomizer technologies were evaluated ¨ two pneumatic
(035H nozzle from HART Environmental and a HEART nebulizer) and a
collection of three piezoelectric/ultrasonic operating at 1.7M:Hz (from Best
Modules
Corp.). All atomizers used the same local well water. In Figure lithe results
of a
measurements with the 635nm red laser are shown, used to estimate the
concentration of fog from the HEART nebulizer when comparing with the results
of MontCarl simulations, suggesting Nd on the order of I06/cm3, which is
comparable
to the measured concentrations of known nebulizers.
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1002931 Two identical, commercially available 1-lomeSoap units were purchased
from Amazon. Each stands vertically like a small computer tower and has a
front
door that opens to a cavity that is 3.6" wide, 9.2" tall, and 13.1" long.
There is a
tubular UVC lamp along the top that runs most of the length of the cavity, and
it is
5 protected by a UVC transparent glass tube. Another UVC lamp runs parallel
at the
bottom of the unit beneath a UVC transparent glass plate. Depressing the
button on
the front runs an automatic 10-minute cycle. The front door was modified to
allow
injection of fog and access to the cables from the two UVC sensor pucks, an
upper
UVC sensor facing the upper lamp, and a lower UVC sensor facing the lower
lamp.
10 The units are not specified to work with dry fog. Both units performed
flawlessly,
even the one with many dry fog cycles.
1002941 In Figure 25 a drawing of the modified HomeSoap unit is provided. As
shown, to achieve shadowing, an adjustable height platform supported the upper
UVC sensor that faced a UVC absorbing polycarbonate sheet placed in front of
the
15 entire left wall of the cavity. The platform could easily be raised and
lowered to
measure performance for different thicknesses of fog between the upper lamp
and the
upper UVC sensor. Another polycarbonate sheet covered the entire bottom glass
plate, blocking all the UVC from the bottom lamp, except for a hole for
receiving the
lower UVC sensor that faced the lower lamp. This sensor was pressed against
the
20 plate in order to eliminate fog as a variable for the lower lamp
measurements. This
configuration was purposefully constructed to make it very difficult for UVC
rays to
reach the upper UVC sensor via dry fog scattering.
1002951 In Figure 27 a chart shows data at five different vertical distances,
d,
between the upper UVC sensor and the bottom of the upper UVC lamp, with the
25 sensor facing sideways at a UVC absorbing polycarbonate sheet to create
a shadow.
At d=4.69", the sensor received 242% more UVC when fog was used, than when no
fog was used.
1002961 In Figure 28, a chart also shows data at five different vertical
distances, d,
between the upper UVC sensor and the bottom of the upper UVC lamp, but here
the
30 upper UVC sensor faced upwards to receive direct-light from the upper
lamp. The
polycarbonate sheet along the left side was removed, but the one on the bottom
glass
plate was left in place. At d=4.85", the sensor received 79% of the UVC when
fog
was used than when no fog was used. This does not mean these LTVC rays were
lost
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91
or absorbed ¨just scattered, and some available to strike other objects to be
disinfected. The measurements also appear consistent with the % transmission
numbers from the Monte Carlo simulations.
1002971 The previous data were taken at the 9:45 mark of each 10-minute cycle.
That is because of the temporal effects from the lamps, which appear to be
traditional
warmup effects of tubular lamps that emit 254nm. Note that the HomeSoap
documentation does not state the specific lamp chemistry, but it does state
254nm.
The chart in Figure 29 shows both cold-start and warm-start cycles. For both
cases,
you can see the measured irradiance is stable after the 6-minute mark.
1002981 The temporal effects on irradiance as fog filled the HomeSoap cavity,
starting at the 6-minute mark, for one cold-start and three warm-start cycles
is shown
in Figure 30. At 8 1/4" of fog thickness, the direct view stabilized fog
irradiance
averaged to 73% of the no-fog irradiance when these cycles started. Note that
unlike
previous measurements, the 2nd polycarbonate sheet was also removed, allowing
the
UVC from the lower lamp to play a role. Again, the UVC rays that missed the
detector were scattered elsewhere.
1002991 In Figure 26 the upper sensor support scaffolding inside the HomeSoap
is shown along with an exemplary MontCarl ray trace rendering (0511 droplets
at
Nd= 06CM-3, k=254nm, tFoG=5.85") extracted from Figure 4. The ray trace is
canted
by an arbitrary angle, a. It describes an understanding of the test, whereby
to reach the
detector, UVC rays emitted from the lamp need to be offset by some angle, a,
which
is not a direct ray, satisfying the purpose of the test.
1003001 In Figure 5 a drawing was created to show a microbe in a canyon (not
to
scale), without fog, having no direct line-of-sight to the rays from any of
the UVC
lamps that line the top of the drawing.
1003011 In Figure 6 two copies of the exemplary MontCarl ray trace rendering
cited earlier are each centered along the extreme rays of the direct field of
view of the
microbe in the canyon (again, not to scale). This shows that with fog, the
field of
view of the microbe is extended, such that some rays from the lamps can reach
the
microbes, hence expanding their field of view. This is valid since the
specific light
rays in the renderings equally represent light traveling into the fog or out
of the fog.
1003021 The following is a much more detailed discussion of the testing found
in
the '139 application.
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1003031 Shadow testing - There is no standard test by which the effect of
shadowing is characterized (see, e.g., Validation Needed for UV Surface
Disinfection
Applications UV Solutions, Dec-2020). The International UV Association
(IUVA,
Bethesda, MD) has formed a Food and Beverage Safety Working Group to address
this. In the interim, in support of the instant invention, there needed to be
techniques
by which to measure whether, e.g., dry fog scattering (or any other
technology) is able
to address the shadowing issue, and some of those devised as part of the
instant
invention are disclosed, below:
1003041 a) Cylinder containing a dosimeter/radiometer - In one embodiment, a
radiometric sensor is placed within a cylinder transparent to the incident
radiation
(e.g., an acrylic or polycarbonate tube for visible light, a UV grade fused
silica tube
for UVC light). The input aperture of the radiometer can be rotated inside the
tube to
face any direction of interest, e.g., directly facing the light source and
facing away
from the light source (e.g., rotated 90 degrees away from the direct line of
sight to the
light source). On the outside of the cylinder, different shadow inducing
structures can
be affixed. The approaches disclosed below were devised to be very repeatable,
such
that anyone could construct the same test easily. The visible light sensor is
P/N
UT385 from Uni-Trend Technology (Guangdong Province, China). The UVC sensor
is P/N UV512C from General Tools & Instruments (New York, NY). The
polycarbonate tube was 1" ID x 1 1/4" OD and cut to 12" in length and
purchased on
Amazon.
1003051 i) Vinyl tape (black) loop around the tube to create a shadow - In one
experiment using the setup of Figure 10, 3/4" wide black vinyl electrical tape
was
wrapped in a single loop around a clear 11/4" OD (1/8" wall thickness)
polycarbonate
tube in a ring-fashion, such that it cast a shadow from a visible white-light
semi-
collimated (25 Cree spotlight) LED onto a wide FOV sensor embedded within a
paddle/wand mounted within the cylinder (the center of the active sensor
surface was
about 0.27" from the inside surface along a radial line). See Figure 10. Four
sets of
measurements were taken. One set was taken with the radiometer sensor facing
the
source (but in the shadow of the tape), and second set of measurements were
taken
with the addition of a dry fog at various thicknesses. A third set was taken
with the
radiometer rotated 90 degrees within the cylinder about the cylinder's axis
(but again,
still in the shadow of the tape). A fourth set was like the third set but with
the addition
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of the dry fog at various thicknesses. The purpose of this testing was to
determine
whether the addition of dry fog scattering caused more light to reach the
sensor than
without the dry fog when the sensor is occluded by a smooth surface.
1003061 ii) Magnetic balls looped around the tube to create more complex
shadows
- In another experiment using the setup of Figure 10, 5mm OD black rare-earth
magnetic balls were strung in a
single line and then wound tightly around the same polycarbonate cylinder in
place of the vinyl tape, with a sufficient number of windings to ensure the
sensor
was in the shadow of the balls. There are small apertures
between adjacent magnets formed by the round surfaces of the magnets. The same
four sets of tests were conducted as with the black vinyl tape. The purpose of
this
testing was to determine whether the addition of dry fog scattering caused
more
light to reach the sensor than without the dry fog when the sensor is occluded
by a
textured surface. Black magnetic balls were used in the visible light
experiment to
more closely emulate the low reflectance of materials to UVC light.
1003071 i) Visible light testing
[003081 Test results for the above two conditions based on a fog from a HEART
Direct Connect High Output Nebulizer (P/N 100610, Westmed, Tucson, AZ) at 50
psi
air
pressure and 20 LPM air flow rate set on a 0-25 LPM Air Click Flowmeter, P/N
AF-
3021, WT Farley (Ladson, SC). Dry fog (using tap water) from the HEART
nebulizer was directed via standard 22mm corrugated tubing (see, e.g.,
AirLifee
22mm Corrugated Tubing, segmented every 6", available from Care Express
Products, Inc, Cary, IL) into a chamber (Polypropylene 19 Quart
WEATHERTIGHT heavy-duty storage tote, UPC 762016445380 with interior
dimensions 15.75" (L) x 7" (H) x 10.25" (W)) through a bulkhead connector
inserted
through the H x L sidewall as shown. The overall hose length was 18", plus an
additional 2" for the connector to the chamber. The near end exterior H x W
face of
the tote was illuminated by an external white LED spotlight (Cree P/N SPAR38-
1503025TD-12DE26-1, 16.9 watt, 3000K, 25 Spot, approx. 4" exit aperture)
aligned
along the central axis of a set of slip-fit PVC tubes (4" nominal diameter)
mounted in
a partition within the tote, across the 1-1. x W as shown. A clear plastic
window was
attached and sealed to the far-end of the inner 4" ID PVC tube, where the
outside face
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of the window could be slid to distances between 0" and 4", via a slip fit
with the
outer PVC tube, from the face of a clear polycarbonate tube (1" ID x 1 1/4" OD
and
cut to 12" in length, purchased on Amazon from the Small Parts brand, P/N TPC-
125/20-24) installed across the width of the tote as shown. The slip-fit PVC
can be
thought of as a telescopic projector, as the input to the window is always
devoid of
fog, and thus any light within the tube does not begin to scatter (except for
scattering
from the inside of the tube surface, the degree to which depends upon whether
the
tube is in its natural white state or lined with a black flocked absorber)
until it exits
the window as the distal end of the tube. Within the polycarbonate tube a
visible light
sensor paddle from a laser power meter was placed, with the sensor aperture
facing
either the center of the LED beam (in the H x W plane) or 90 degrees rotated
therefrom (in the W x L plane). The laser power meter was P/N UT385 from Uni-
Trend Technology (Guangdong Province, China). The sensor paddle was pressed
against the inside face of the polycarbonate tube by placing a 1/4" diameter
wooden
dowel encased in a 'A" ID x 3/8" OD silicone tube (purchased from Amazon)
against
the backside of the sensor. The sensor paddle was shadowed either by a single
loop of
3/4" wide black vinyl tape or 10 windings of close-packed 5mm diameter black
rare-
earth magnetic balls. A wide field of view (FONT) source monitor (Light
ProbeMeter
P/N 403125 from Extech, Waltham, MA, now part of FLIR Commercial Systems Inc.,
Nashua, NH) was placed as shown such that it caught enough stray light to
register a
high enough signal in order to catch any pertubations of the raw LED beam, yet
did
not cast a shadow into the fog). No effort was made to mix/homogenize the dry
fog ¨
it entered the far side of the chamber through a custom-made 22mm bulkhead
connector as shown and was allowed to naturally circulate. The flow pattern in
the fog
chamber was different depending upon the penetration of the telescopic PVC
tube into
the fog chamber. This could be seen by the movement of the large droplets that
were
visible (a proportion of dry fogs will have a distribution of droplet sizes, a
small
percentage which are visible). The humidity inside the chamber was measured
separately using a Hygro-Thermometer, P/N 445815 (Extech), and it consistently
reached 100% after allowing the dry fog to reach its maximum concentration.
The in-
chamber humidity measurements were made in the winter in early 2021, with room
RH between 20% and 30%. As cited elsewhere herein, the high RH minimizes, to
the
degree possible, evaporation of the dry fog.
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1003091 Testing was performed with the white LED spotlight and the HEARTS
nebulizer dry fog with one wrap of black tape covering the section of the
polycarbonate tube within which the sensor paddle was aligned, facing the LED
spotlight, such that direct light from the LED spotlight was blocked. See
Figure 10.
5 Data was taken every 15 seconds out to 4 minutes run-time. One set of
measurements
was made with the telescoping 4" PVC tube with a black flocked interior liner
(Figure
14) without adhesive backing (see, e.g., Edmund Optics Inc., Barrington, NJ,
P/N 60-
068). The black liner prevents scattering from the inside of the PVC tube,
maintaining
the semi-collimated light from the white LED spotlight. The telescoping tube
10 protruded through the dry fog isolation partition as shown (Fig. 10) for
fog
thicknesses of 1/4", 1", 2", 3", 4", as before.
1003101 In Figure 14, as mentioned, the test was configured with the 4" PVC
tube
having its inside surface lined with black flocking paper. So, as semi-
collimated white
light from the LED spotlight hits the wall, it does not scatter. There is no
fog inside
15 the inner PVC tube, as the window on the distal end is sealed to the end
of the tube.
The solid lines on the chart are the normalized data from the laser power
meter inside
the polycarbonate tube, and the dashed lines depict the % change in light
relative to
the fog-free condition for that fog thickness.
1003111 The normalized sensor curves, from highest to lowest are: a tight
grouping
20 of 1", 2", 3", 4" (3" lagging at the start), with 1/4" distinctly lower.
1003121 The % intensity change relative to no fog curves, from highest to
lowest
are: 3", 2", 4", 1", 1/4". The % intensity change relative to no fog at
stabilization of --
208% is a maximum at a 3" fog thickness, followed by 2" (184%) and then 4"
(152%), suggesting that there is a preferred fog thickness for this
configuration. Ray
25 tracing can be used to cross-check these results.
1003131 The normalized sensor readings (solid lines) at the end of elapsed
time (the
'stabilized' values shows 1/4" distinctly lower than the other distances. It
is likely that
there is not enough fog in the 1/4" gap at the number concentration from the
HEART
nebulizer to provide much scattering. It is not known whether the flow
dynamics in
30 the tote favor certain gap distances between the tubes, although it is
surmised from the
data that this effect is minor, as the excursions about a smooth-curve
`trendline' (if
one was plotted) are not substantial. Said differently, voids in the fog
distribution will
tend to fill in over-time, as would be expected in consideration of entropy.
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1003141 Notice on the plots of Figures 14 that the curves resemble resistor-
capacitor (RC) exponential charging curves. In simplistic terms, the fog
builds up in
the fog cavity like charge in a capacitor, and the scattered light increases
the amount
of light working its way around the black vinyl tape to the shadowed sensor.
The
amount of light appears to hit a maximum after about 2 minutes. It is (a)
unlikely that
by-chance the number concentration is optimized, and that (b) the optimal
number
concentration is likely higher, rather than lower. The reason it is not lower
is because
the data was taken over time, and there was no definitive local maximum before
the
elapsed time, and the number concentration was lower before stabilization. So,
this
suggests that the dry-fog concentration can be further increased for
additional benefit.
However, the concentration appears to hit a limit with the single HEART
nebulizer
in the fog chamber, which could be due to one or more reasons cited below.
1003151 One reason could be that as the fog reaches a certain concentration,
there is
an equilibrium between the incremental fog added from the continuous feed from
the
HEART nebulizer and the incremental fog that evaporates within the chamber.
1003161 Another reason could be that there is back-pressure that builds in the
fog
chamber (also suggested by a review of Figures 20 and 21) until the HEART
nebulizer becomes limited in the amount of incremental dry fog it can supply.
A
0-60psi pressure gauge was connected to the fog chamber, but no pressure above
ambient is detected on the gauge (even after 5+ minutes), however, the
flexible clear
film cover on the fog chamber does bulge a bit after fog is first introduced
and does
not collapse until the chamber is vented to ambient. Also of note, the
compressed air
continues to be consumed by the nebulizer, and some fog swirling is noticed
within
the chamber at the 5+ minute mark. Fog does not appear to be leaking out of
the
chamber (the large droplets are visible and easily seen when leaking). Various
leakage
tests are shown in Figures 20 and 21.
1003171 Yet another reason is that the smaller invisible dry fog droplets are
leaking,
but the larger visible fog is not.
1003181 Going back to the RC charging analogy, one can roughly think of the
dry
fog analogous to an electrical current, and the pressure into the nebulizer
analogous to
a voltage. Based on the pressure gauge reading 0 psi, it appears all of the
pressure is
dropped across the nebulizer (and the flow meter in series with it at the
input).
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1003191 This can be al so likened to the leakage resistance of
a capacitor; see, e.g.,
Insulation Resistance, DCL Leakage Current and Voltage Breakdown ¨ European
Passive Components Institute, that suggests temperature increases capacitor
leakage,
much like temperature increases dry fog evaporation.
[003201 Time constants related to fog charging were made (not shown) based on
the white paper System Dynamics - Time Constants. The approach taken was the
'The
Logarithmic Method', whereby the natural log is taken of the exponential
charging
function in order to linearize the curve. Comparisons are made by just using
the first
45 seconds of the normalized sensor readings during fog charging for each of
the fog
thicknesses. This type of approach can be used to model fog scattering
applications
that periodically inject and/or exhaust fog from a volume, where the process
is
terminated after a desired number of time constants.
1003211 In an effort to understand whether the protrusion of the 4" PVC tube
at
different distances into the fog chamber made a difference, the chamber was
turned 90
degrees as shown in Figure 15, where light was introduced 'cross-wise' below
the
level of the 4" tube, using a black flocking to block light from the spotlight
impinging
on the PVC tube, but allowing it to travel under the tube As shown in Figure
16, the
scattering was largely unaffected by the position of the 4" PVC tube in the
chamber. It
was theorized that there would be some differences in scattering in the cross-
wise
setup of Figure 15 if the fog were sealed within the chamber vs. allowed to
leave the
chamber in different manners, all while fresh fog was continually injected to
the
chamber as in the other tests.
[003221 Various test cases are shown in Figures 20 and 21 by which the fog
could
exit (or not):
1003231 1. Top sealed, brass bulkhead connector (0 0.72") in the side of
chamber
unplugged.
1003241 2. Top sealed, brass bulkhead connector (0 0.72") in the side of
chamber
covered with MERV16 filter paper (breathable Non-Woven Polyester Polycarbonate
(NWPP) - 95 Percent Efficiency, purchased from Biodefensor Filters, City of
Orange,
CA, via Amazon). MERV16 was used since it is sold as 'captures particles small
as
0.3 microns', thus allowing air molecules to pass through, but not the bulk of
the dry
fog droplets.
1003251 3. Top covered in MERV16, sealed around its edges to the chamber.
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1003261 4. Open top.
1003271 5. Top opening 11/2" x 9".
1003281 6. Full cover over top, not sealed.
1003291 As shown in Figure 20, only the test with the top of the chamber
removed
('Open top') had any substantially different intensity loss relative to the no-
fog
condition. However, this likely indicates that in this test, a larger amount
of the fog
was lost because the number concentration was lower - thus less scattering,
and
therefore a higher cross-wise measurement during the fog cycle. The other
configurations did not have an appreciable difference, so as long as the fog
were
somewhat contained (not necessarily in a totally sealed chamber, which was
somewhat surprising, and fortuitous, allowing for simpler containment, e.g.,
in a UVC
tunnel). Figure 21 shows the same data, but the secondary axis has been
narrowed
between -80% and -90% to look at the small differences between test cases.
[003301 Interestingly, other than case number 4 cited above, case number 5
(Top
opening 11/2" x 9") had the highest amount of scatter losses, followed by case
numbers
1, 3, 6, and 2, although these were all within about 5% of each other.
1003311 Another part of the analyses was to understand the effect on air
pressure
and flow rate to the scattering from the HEART nebulizer. See Figure 17. It
shows
that higher pressure and higher flow rates increase scattering, with 45ps1 @
15 LPM
the lowest scattering, and 55psi @ 20 LPM the highest scattering. The
guideline
settings from the HEART manufacturer (for its use as a nebulizer) is 50 psi,
and
either 10 LPM or 15 LPM (the latter for 'higher output').
1003321 Another phase in the testing was to understand whether gravity and/or
flow
dynamics made a difference in the number concentration in the vertical
direction of
the visible light tote-based fog chamber. The sensor was placed at vertical
heights on
the outside surface of the tote as shown in Figure 22, from 7/8" to 4 7/8" in
'A"
increments relative to the bottom of the tote. The data is shown in Figure 23,
as
normalized (fog/no-fog), where the 'normalized' data is the sensor data
divided by the
source monitor data, the no-fog is the reading at time=0, and the fog is the
reading
after 3- minutes elapsed time. There is also shown vertical line that depicts
the vertical
height of the fog injection port. The data shows very little difference with
respect to
vertical height, except for a bit of a step for heights above the vertical
height of the
injection port. This suggests that the flow dynamics plays a role in the
uniformity of
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fog concentration, even after stabilization time. CFD analyses can help
understand
this better, as can testing, see, e.g., Flow visualization of an N95
respirator with and
without an exhalation valve using schlieren imaging and light scattering.
1003331 It is also important to note that the number concentration of the fog
was
not quantitatively measured by dedicated instrumentation. Initial testing of
the fog
(the same HEART nebulizer) with the tote (without the partition) was
performed
with a red 635nm laser, Beamshot 1000 from Quarton, Inc. (New Taipei City,
Taiwan). The laser light traversed the fog along the entire length of the
tote. The laser
power meter was placed at the peak intensity of the beam as it exited the
tote. The
maximum forward intensity was measured at 0% fog, and airflows of 20 and 25
LPM.
The two airflow rates will produce different distributions of dry fog. The
ratio of the
maximum intensities (without fog / with fog) was calculated as shown in the
upper
table in Figure 11. Monte Carlo simulations (MontCarl) were also run using the
same
wavelength, fog thickness, and monodisperse water droplet diameters, and
provided
the change in peak intensity of a 635nm laser versus changes in number
concentration
(peak intensity will lessen the more the scattering broadens the beam, which
is
intuitive) This is summarized in the lower table of Figure 11. By measuring
the
change in peak intensity from no-fog to maximum fog number concentration, one
can
(to a rough degree) compare the measured peak intensity reduction data to the
Monte
Carlo simulations and deduce the number concentration. The data in the lower
table is
plotted in Figure 11. Thus, the measured 'Factor reduction' in peak intensity
(from 20
LPM to 25 LPM air flow at 50psi) correlates to a number concentration within
about
7E5 cm' to 2E6 cm", assuming the measured data was taken from a monodisperse
water fog of droplet diameter 3.6p. Again, while not exacting, it shows in
fact that the
HEART nebulizer could generate a sufficient number concentration to scatter
the
beam. Also note that this estimate is fairly consistent with the
nebulizer/compressor
combinations disclosed in Fig. 9 of Dynamics of aerosol size during inhalation
-
Hygroscopic growth of commercial nebulizer formulations.
1003341 Figures 12 and 13 provide Monte Carlo simulation results (via
MontCarl)
for various water fog (3.6 diameter droplets) number concentrations from 0
through
1E9 cm' (using a 635nm laser, and a fog thickness of 385mm). Is shows that
around
1E6 cm" about 75% of the rays transmit in a forward direction, with a fair
amount of
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spread from scattering. It also shows that around 2E8 cm-3, the forward
transmittance
is under 1%, with the maximum distance through the fog at just over 4".
1003351 The same 635nni red laser was tested on a smaller chamber (12 quart
polycarbonate, 12.68" (L) x 10.39" (W) x 7.76" (H), model C10 from Lipavi,
Hertfordshire, England) that hosted three ultrasonic Water Atomization
Modules, P/N
BMZ00040 from Best Modules Corp. (Hsinchu, Taiwan) each with a 10 watt
1.7MHz, 20mm diameter piezoelectric ultrasonic transducer. The water height
above
the transducers was set to about 1 cm. With all three operating at 10W, the
generated
fog cloud was about 2 inches thick, riding on top of the surface of the water.
The
635nm laser was aimed into the fog, and it could only progress through a
distance of
about 4 inches. This indicates that the number concentration was higher than
that
produced by the HEART nebulizer, since the Monte Carlo simulations in Figure
12
show that as the number concentration increases to about 1E8 cm-3, the
incident
radiation, e.g., from a laser, begins to turn back toward the source. In fact,
looking at
the simulation results in Figure 13 (only a slightly larger droplet radius),
the number
concentration (assuming monodisperse droplets as a rough approximation) is
between
1E8 cm-3 and 1F9 cm-3 Since it is easier to dilute a concentration than
increase it
(entropy), the ultrasonic (piezo type) approach provides a method by which a
dry fog
field can be tuned to any desired degree of forward scattering (in addition to
a portion
or none of backward scattering, if desired). Depending on the application and
the
desired amount of scattering, a (controllable) range of Nd values can be
selected
(using, e.g., a scatterometer or via measurements of the end-effects of the
irradiation)
for a given range of irradiation wavelengths, scatterer sizes (and shapes),
and fog
thicknesses (assuming the environmental conditions can support such
concentrations
vis-A-vis evaporation, wetting, etc.). Figures 3, 4, 12 and 13 (and others in
the
provisional filings) provide examples of the sensitivities to parameter space.
1003361 A comparison of scattering via Monte Carlo simulations conducted at a
100
HWHM beam at 280nm, 405nm, and 630nm for 5p droplets at the same layer
thicknesses was performed (not shown). The results are about the same for all.
1003371 To understand the reasonableness of the estimate of the HEART number
concentration, see Effect of evaporation on the size distribution of nebulized
aerosols.
It shows that both compressed air (pneumatic) and ultrasonic nebulizers
operate at a
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number concentration of at least 106/cm3 This is consistent with the
measurements
made above.
1003381 It is noteworthy that the dry fog, at least the visible portion,
output from a
hose connected to the HEART nebulizer follows gravity and drops to the bottom
of
an empty container, indicating it would also drop on to a conveyor belt that
carries
produce for disinfection. See also the discussion and formulae for
sedimentation (and
evaporation) in Mechanisms of Airborne Infection via Evaporating and
Sedimenting
Droplets Produced by Speaking. It shows dry fogs evaporate orders of magnitude
faster than their sedimentation time, and it also states, "Solutes in the
droplet decrease
the water vapor pressure and therefore limit the droplet radius in evaporation
equilibrium ...", i.e., adding stuff to pure water may enable the droplet to
evaporate at
a lower rate. Water vapor pressure decreases with a decrease in temperature,
and thus
further limits evaporation as can be seen in Vapour pressure of water ¨
Wikipedia.
1003391 In a preferred embodiment, an array of nebulizers line either side of
a first
enclosed portion of a tunnel conveyor system, discharging a layer of fog on
top of
product to be disinfected. Stationary sidewalls on either side of the conveyor
belt
prevent the fog from falling away. Airflow is controlled to ensure the fog is
not swept
away (although enough to ensure good mixing may be suitable). The belt then
moves
the product into the adjacent second enclosed portion of the tunnel that is
configured
with UVC lamps that cast their light through the fog onto the product. UVC
reflective
walls will aid in recycling light back to the product. Very dense dry fog
layers at the
lowest level can also provide efficient reflection via backscattering (see the
Monte
Carlo simulation results herein for the number concentrations needed for
backscatter).
The product can either be rotated in the plane of the belt in this section to
ensure full
UVC coverage of all product surfaces (see reference to product rotation during
irradiation in, e.g., Fruit Preservation, ISBN 978-1-4939-3309-9, Ch. 17
'Fruits and
Fruit Products Treated by UV light', The effect of fruit orientation of
postharvest
commodities following low dose ultraviolet light-C treatment on host induced
resistance to decay), or a second section can be installed to first flip the
product, then
add fog and UVC as previously described. UVC reflective PTFE belting can also
be
employed to maximize efficacy while providing a cleanable surface suitable for
food
products. See, e.g., Maine Industrial Corp. (Newcastle, ME) and Green Belting
Industries Ltd. (Mississauga, Ontario, Canada). Any condensation collected on
the
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handling equipment can be evacuated and drained when the belt turns upside-
down at
the end of its travel.
1003401 In preferred embodiments, a system would be tested to determine the
optimal fog number concentration and thickness as shown in the above testing.
For
example, testing may show that strawberries and tall loaves of bread require
different
settings. In addition, changes in other system settings such as particle size
distribution,
UVC irradiation patterns, etc., may be necessary to optimize a production line
for a
given product. Dosimetric avatars as discussed herein will be helpful in that
regard.
1003411 In another preferred embodiment, fog is injected in the same section
of a
UVC tunnel as the UVC. Airflow from outside the tunnel system is blocked by
one or
more of: vinyl strip curtain doors, automated mechanical doors, air curtains;
see, e.g.,
Jamison Door (Hagerstown, MD), NORDIC door ab (Halmstad, Sweden). Various
food conveyors with tunnels can be adapted as well, such as those from Project
Services Group, Inc., (Irving, TX).
1003421 ii) UVC light testing - A HomeSoape UVC desktop sanitizer was
modified to allow injection of dry fog through a pass-through (i.e.,
'bulkhead')
nebulizer connector (P/N 1422, 22mm OD, 15mm TD, Hudson RCT, Temecula, CA)
installed through the lower portion of the front access door, as well as a
small notch at
the bottom of the front door for the radiometer cable to pass-through. The
HomeSoap unit contains two tubular 254nm emitting lamps according to their
product specifications, one on the top of the unit, and another on the bottom
of the
unit (beneath a UVC transparent quartz glass sheet). The inside dimensions of
the unit
are specified as 93.04 mm wide x 234.61mm tall x 334.74 mm long.
1003431 A scaffolding as shown in Figure 25 was used to position the upper UVC
sensor (UV512C) in the shadow of the upper tubular UVC lamp. A machinist-grade
uncoated steel '1-2-3 Block' (measures 1" thick, 2" wide, 3" long) is used as
a base
weight, and another as a platform for the upper UVC sensor. Corresponding
threaded
holes in the blocks receive a threaded rod, and thus the upper Block can be
spun on
the threaded rod to change its vertical height, h, from the UVC absorbing
polycarbonate plate (PC) that was placed on the UVC transmitting quartz glass
plate
the manufacturer supplies at the bottom of the HomeSoape unit (PC is used to
absorb
UVC that would otherwise reach the upper UVC sensor). By changing h, the
distance,
d, from the center of the upper UVC sensor to the bottom of the upper UVC lamp
can
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be modified. A clearance hole drilled in the PC plate near the front door and
above the
near end of the lower tubular UVC lamp receives the bottom puck-style UVC
sensor,
which is placed face down and in contact with the quartz plate in order to
prevent any
substantive fog between this sensor and the lower lamp. For the greatest
distances, d,
the upper 1-2-3 Block is removed, and the sensor is placed on the lower 1-2-3
Block.
Note that the distance, d, of the sensor to the underside of the UVC
transparent tube
surrounding the upper UVC lamp is such that (d + 11/16" + h) z-; 9 1/8" (the
puck
radius is 11/16"). Also note that the transparent tube (likely UVC transparent
quartz)
surrounding the upper lamp is part of the HomeSoap design, presumably to
protect
the lamp from damage during use since there is no upper quartz plate like that
used on
the bottom. A separate PC sheet covers the entire left sidewall to prevent UVC
reflected from the sidewall to reach the upper UVC sensor, thus creating a
'shadow'.
Note that for simplicity, only the left sidewall and bottom surfaces are
covered in PC
sheet, so some (minor) reflections from the other surfaces reached the upper
UVC
sensor without the use of dry fog. There is a gap, w 1.2", between the sensor
element of the upper UVC sensor and the PC sheet covering the left sidewall.
As
shown in Figure 25, the front face of the UVC sensor is approximately in the
plane
formed between the longitudinal centerlines of the upper and lower UVC lamps.
[003441 The scaffolding as shown in Figure 25 is also used to position the
upper
UVC sensor in the direct view of the upper tubular UVC lamp by placing the
puck-
style sensor with the side opposite to the active sensor lying against the
upper 1-2-3-
Block (not shown). For this case, the height, h, to the top of the upper UVC
block is
again set as before using the threaded rod, but the distance, d, of the sensor
to the
underside of the quartz tube surrounding the upper UVC lamp is such that (d +
1" + h)
9 1/8" (the puck is 1" thick).
1003451 For safety purposes, prior to the start of UVC testing, a .095" thick
polycarbonate (PC) sheet was placed across the outside of the front door to
the unit to
block a substantial portion of any stray UVC light from propagating through
the fog
injection connector or the 'mouse hole' for the sensor cables to pass-through.
As an
aside, the UVC was measured at the fog injection port (without the PC blocking
sheet)
at about 1[rW/cm2. Nonetheless, safety glasses were worn even with the PC
sheet in
place.
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1003461 In order to introduce dry fog, a 22mm corrugated hose was connected
from
the same HEART nebulizer onto the bulkhead nebulizer connector that was
mounted on the door of the HomeSoap unit.
1003471 It is important to understand that the two UVC lamps in the HomeSoap
are tubular emitters (not point-like LEDs), specified as emitting UVC light at
254 nm,
but no reference as to whether they are what they appear to be - low pressure
mercury
lamps. In some sense it really does not matter, except when trying to make
sense of
their temporal behaviour. Although not dispositive, according to parent
company
PhoneSoap's patent filing, US9339576 Portable electronic device sanitizer, "As
a
non-limiting example, a low-pressure mercury-vapor lamp emits EO radiation at
peak
wavelengths of approximately 184 nm and 254 nm. While both wavelengths can be
used to sanitize a PED, 0 radiation of 184 nm will also produce ozone, which
may
be undesirable. Accordingly, the low-pressure mercury-vapor lamp may be used
in
conjunction with a filter designed to block 184 nm EO radiation while allowing
254
nm EO radiation to pass through." None of the HomeSoap documentation
specifically cites the use of 'mercury' in the product.
1003481 The output radiance of the lamps varies greatly during a cold-start
(when
the unit has not been used and the lamps start off at room temperature) and
the lamp
begins to heat up, which is a characteristic of low pressure mercury lamps.
See, e.g.,
Demonstration and evaluation of germicidal UV-LEDs for point-of-use water
disinfection.
1003491 iii) Discussion re: temporal changes in dry fog number
concentration -
The visible light testing with the tote allowed inspection inside the tote as
the fog was
introduced. Such is not the case with the HomeSoap , as it is opaque owing to
the
safety precautions in the use of UVC light (and other design-related choices).
1003501 The interior volume of the fog chamber portion of the tote is about
575 in3,
while that of the HomeSoap is about 445 in3 (using the interior dimensions
specified
by the company, neglecting the volume taken up by the modifications). The
HomeSoap is therefore lower in volume than the tote, and so should stabilize
in
concentration before the tote, and the tote stabilizes in under 3 minutes (180
seconds)
based on the time-sequential plots of scattered visible light readings taken
(not
shown).
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1003511 iv) HomeSoap testing - The liomeSoap unit starts by pressing the
power button, and the operates for 10 minutes after which it shuts off
automatically.
Figure 29 shows the results of 42 individual 10-minute cycles in the HomeSoape
unit, with 25 data samples taken on the lower lamp per cycle (using the 'UV
Clean'
UVC radiometer from Apprise Technologies, Duluth, MN) as evidenced by the
circular and square markers. During each cycle, data was manually recorded
from the
upper and lower UVC sensors, using a stopwatch to gather data at fairly
precise time
increments. Note, however, that the first data are taken 15 seconds after turn-
on (i.e.,
elapsed time) since it was difficult to manually record data any sooner.
Further, the
last data was taken at the 9:45 (min:sec) mark to avoid a race condition in
taking data
precisely at the 10-minute mark. Note the data is stable at about 420 seconds
of
elapsed time (i.e., 7-minutes into the cycle) due to the temporal effects of
lamp
temperature (the lower UVC sensor is pressed against the bottom quartz glass,
and
thus is not affected by the scattering fog). The cold start cycles clearly
show a
characteristic mercury lamp warmup curve. 'Cold start' refers to starting the
unit after
it was off for at least about 45 minutes. 'Warm start' refers to starting
within about 45
seconds from the end of the previous cycle The data at the 9:45 mark will be
referenced as 'stabilized' for purposes of this discussion. Also note the
spread of the
stabilized values. Lamp temperature performance, including cold spot reference
data
is cited in Fundamental Characteristics of Deep-UV Light-Emitting Diodes and
Their
Application To Control Foodbome Pathogens.
1003521 Some observations re: visible and UVC dry fog scattering are discussed
below.
[003531 (1) Any plotted data showing fast-moving changes on the order of
seconds
are likely due to rapid changes in dry-fog concentration as the fog swirls in
the
chamber (nothing was done to move/mix the dry fog within the chamber). In an
exemplary embodiment, the chamber can be stirred as necessary to maintain a
hornogenous fog concentration throughout the chamber.
1003541 (2) Figure 14 suggests there is an optimal fog density and thickness
to
maximize the intensity of the light onto the shadowed sensor. In fact, the
curves do
not show a pronounced maximum with a significant downwards slope, indicating
that
an even higher dry fog concentration would be more efficient A control system
can
be implemented to achieve this in many ways, incorporating one or more of
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activating a valve to maintain the concentration at maximum efficacy by
selectively
venting excess fog out of the chamber (passively or actively via a fan),
controlling the
amount of fog injected into the chamber by changing the flow rate into the
chamber (
e.g., lowering the power to one or more ultrasonic atomizers or venting a
portion of
the flow in a manifold), modifying the flow rate of objects ( e.g.,
strawberries)
through a chamber ( e.g., UVC tunnel), changing the environmental conditions
(temperature and/or R1-1) to alter the rate of fog evaporation,
raising/lowering a UVC
plate below the conveyor belt to change the volume of the chamber ( e.g., if
illuminating the objects via UVC lamps above and below the conveyor belt, then
the
plate would be a UVC transparent plate), etc. Another approach in optimizing
the
scatter is to use a similar telescopic projector as was done with the visible
light testing
described herein, where a tube devoid of fog and fitted on its distal end with
a window
(or other optical component such as lens, diffuser, etc.) telescopes into the
fog within
the UVC tunnel, such that the fog concentration remains about the same, but
the fog
thickness changes as the telescope extends & retracts.
[00355] (3) Obstructions to the flow/infiltration of dry fog in and around
objects
can be left to passive means (settling by gravity and natural air currents) or
can be
retarded/expedited as desired via electric charges, pressure gradients and the
like. In
one exemplary embodiment, a UVC tunnel is fitted with one or more plenums with
nozzles that direct dry fog at objects that move along a conveyor belt within
a UVC
tunnel. The nozzles are positioned, e.g., based on the profile of the objects,
and thus in
this exemplary embodiment, one or more of the nozzles are moved (and/or spray
profile adjusted) to optimize the fog distribution as desired. This movement
can be
done manually and/or automatically as defined in a computerized configuration
file.
[00356] Note that for some applications, all surfaces of an object need not be
treated using the dry fog scattering light technique. It may be that, e.g.,
only high-
touch surfaces are disinfected using UVC with dry fog, such as the touch
screen area
of an automated teller machine (ATM). With respect to food, some food may have
smooth surface portions and distinct textured surface portions, wherein the
smooth
surfaces may be disinfected with UVC without dry fog (and/or minimal/residual
dry
fog), and the textured surfaces are disinfected with UVC utilizing a healthy
concentration of dry fog. With respect to visible/MR light irradiation of
plants, it may
be only the top surfaces of the leaves. Of course, handheld operation of a UVC
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irradiator with fog (e.g., during cleaning of the interior cabin of an
airplane) would
likely treat only predefined surfaces as established by an airline company. A
robotic
application may have sensors that determined which surfaces to treat with the
combination of light and dry fog, in some instances by automated pathogen
detection.
See, e.g., Frank StUpmann -
Poster GerniDetect immediate detection of biotic contamination Stuepmann
(2021).
1003571 Some recommendations re: operating in fog/high-humidity:
1003581 1) On the HS unit, the lower UVC lamp is below the fog, which is not a
recommended location due to the fog sinking under the effects of gravity. See,
e.g.,
"Do not install beneath a humidifier" BIO-FIGHTER Nomad & Nomad 2 Ultraviolet
Light Systems Installation & Operation Manual. This, however, can be overcome
as
described below.
1003591 2) UVC systems have a long history of operation in humid environments
(e.g., in certain water treatment systems and food processing facilities), and
thus the
industry understands how to ensure systems operate in these environments,
e.g., by
sealing lamps in quartz sleeves: "In the quartz systems, some units are
installed which
either seal the quartz ends or leave them open. In the open arrangement,
convective
air currents can carry air (often humid) through the quartz sleeve, causing
some
deposition on the lamp surface. Additionally, the same air convection will
cause the
inner surface of the quartz sleeve to become dirty. This may also occur to
some
degree in sealed systems due to condensation effects, although there is no
current
information regarding these effects." Design Manual - Municipal Wastewater
Disinfection (1986) ... "EncapsuLampTM technology for superior safety ...
Designed
for direct water wash-downs FEP, or fluoroethylene (FEP), is a synthetic
fluoropolymer used in covering UV Resources' lamps (EncapsuLampTm)" RLM
Xtreme Brochure. ... "The resistance of the FEP/solar cell package to high
humidity
and temperature, thermal shock, and ultraviolet, proton, and electron
irradiation was
evaluated. The process was extended to 15-cell flexible modules, which were
evaluated under similar environmental conditions. The performance of the FEP-
covered cells was encouraging and compared favorably with that of conventional
cover glasses." Investigation of FEP Teflon as a Cover for Silicon Solar
Cells.
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1003601 See also Combined Hurdle Technologies Using UVC Waterproof LED for
Inactivating Foodborne Pathogens on Fresh-Cut Fniits (23-Jul-2021) "There has
been
no research on UV waterproof LED applied in the food industry ... UVC
Waterproof
Lights Emitting Diodes (UVC W-LED) - UV treatments were performed in a
stainless-steel case (32.5 cm x 17.5 cm x 15 cm) equipped with two UVC W-LED
(275 nm) modules (BlueLumi Co., Ltd., Gyeonggi-do, Korea), which were placed
on
each side of a stainless-steel case."
1003611
3) It is known to evacuate dry fog after treatment in chemical dry fogging
systems, e.g., "Dry Fogging Systems (DFS) utilize an ultrasonicator or
aerosolizer to
form very small (1-10 m) particles of disinfectant that are rapidly dispersed
into the
air. The result is the creation of a dry fog of disinfectant that both remains
airborne to
act upon any airborne biological contamination, as well as coating surfaces to
act
upon deposited contaminants. After an appropriate duration, the fog in the air
is
evacuated by vacuum or H.VAC systems, while the disinfectant continues to act
upon
surfaces. These systems typically utilize a peracetic acid solution (0.5-6%,
with or
without hydrogen peroxide and halide ion s)2 and claim a number of benefits
over
manual cleaning methods." A R oad m a p for investigation and validation of
Dry
Fogging as a decontamination technology.
1003621 4) An alternative to engineering solutions related to the effects of
humidity
on LP mercury lamps (and associated ballasts) would be to use UVC LEDs and
their
associated drive electronics. Some effects upon LED systems to be considered
including early life depreciation (like many lamp technologies), hence the use
of
seasoning (Preparation of a standard light-emitting diode (LED) for
photometric
measurements by functional seasoning). Humidity is also a factor (Chapter 17 -
Ultraviolet Lamp Systems - 2020 ASHRAE Handbook - HVAC Systems and
Equipment, however, UVC LEDs can be sealed from the environment using UVC
transparent encapsulants as cited herein. UVC LEDs, like other LEDs, lose
efficacy
with increasing temperature (see, e.g., Luminus ,CBT-3535-UV Surface Mount UVC
LED, Luminus, Sunnyvale, CA). Additional insights are disclosed in Performance
of
chip-on-board and surface-mounted high-power LED luminaires at different
relative
humidities and temperatures. Unlike LP mercury lamps, LEDs are not said to
have an
optimal cold spot temperature dependence, and their forward voltage varies
less than
one volt over temperature. LEDs are relatively easy to cool to maintain high
efficacy
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(see, e.g., Thermal Design Using Luxeon Power Light Sources) compared to
mercury-
based lamps (see, e.g., Maintaining Optimum Fluorescent Lamp Performance Under
Elevated Temperature Conditions).
[00363] 5) Note that any effects on the lamp and/or electronics is separate
from the
efficacy of UVC scattering with dry fog, i.e., the efficacy testing herein is
in effect
normalized to whatever the lamp intensity is. Of course, it is desirable for
the light
source and electronics of the instant invention to be protected from high
humidity as
appropriate, following good design practices. However, as demonstrated with
the test
data herein, systems that are not specifically designed for high humidity
environments
can still work.
[00364] vi) UVC scattered light measurements in shadow and in direct-view of
the
upper HS UVC lamp - The data in Figure 27 shows the results from shadow-based
UVC testing as described earlier. The lower two lines show the consistencies
in the
measurements of fog and of no-fog conditions at each distance (min/max). Based
on
this limited sample size, the consistency of both fog and no-fog increases as
the
distance between the sensor and lamp increases, hits a maximum at 4.69" and
both
decrease as the distance continues to increase, with the fog maintaining a
higher
consistency over the no-fog condition, perhaps due to the homogenization from
scattering in the fog.
[00365] The dashed lines represent the average irradiance measured as a
function
of distance in the fog and no-fog conditions, with the highest irradiances at
the shorter
distances as would be expected. The shape of the curves shows a first slope
from
minimum distance to 4.69", then a lesser slope beyond 4.69". The 'cross'
markers
show the ratio of average fog/no-fog readings, which generally increases from
smaller
to larger distances, although at 4.69" there is a local maximum. The ratio of
fog/no-
fog is a minimum of 1.92 at all distances, i.e., demonstrating a net increase
in
irradiance with fog. For this setup and dry fog droplet size and number
concentration,
the absolute value of the UVC irradiance peaks at 37.5 RW/cm2 at the smallest
distance. It must be said, as before, there is no standard shadow test, so the
absolute
UVC irradiance values shown below, with fog, are specific to this test setup
at the one
dry fog number concentration that was used, etc.
[003661 The data in Figure 28 shows the results from the direct-view-based UVC
testing as described earlier. The upper two lines show the consistencies in
the
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measurements of fog and of no-fog conditions at each distance (min/max). Based
on
this limited sample size, the consistency of no-fog hits a minimum at 4.69",
while the
fog hits a maximum there. As before, there is a convergence of the two lines
as the
distances increases towards 4.69", then both diverge as the distance continues
to
increase, with the no-fog maintaining a higher consistency over the fog
condition.
1003671 The dashed lines represent the average irradiance measured as a
function
of distance in the fog and no-fog conditions, with the highest irradiances at
the shorter
distances as would be expected. The shape of the curves is smoother than the
shadowed configuration above. The 'cross' markers show the ratio of average
fog/no-
fog readings, which is a maximum of 87.9% at the shortest distance measured
(for this
configuration), and then decreasing as the distance increases, with a marked
decline at
7.17". The ratio of fog/no-fog is much less than the shadow configuration. The
absolute value of the UVC irradiance is much higher than the shadowed
configuration, as would be expected.
1003681 c) Dosage versus log-reduction - For the instant invention, it is
useful to
understand the incremental log-reduction that can be obtained by an
incremental
fluence, i e , if the irradiance is doubled, what is the incremental log-
reduction? This
varies by microorganism, and thus the desired incremental fluence can be
application
specific, as some applications are focused on the effects of a small group of
pathogens.
1003691 In Fluence (UV Dose) Required to Achieve Incremental Log Inactivation
of Bacteria, Protozoa, Viruses and Algae (the 'Source article') there are
tables that
"present a summary of published data on the ultraviolet (UV) fluence-response
data
for various microorganisms that are pathogens, indicators or organisms
encountered in
the application, testing of performance, and validation of UV disinfection
technologies. The tables reflect the state of knowledge but include the
variation in
technique and biological response that currently exists in the absence of
standardized
protocols. Users of the data for their own purposes are advised to exercise
critical
judgment in how they use the data." Given the caveats, the data is especially
useful
for understanding general trends.
1003701 Figure 2 is a summary of different types of microorganisms and the
'fluence multiple' needed to achieve incremental 1-log and 24 og reductions
(for Low
Pressure mercury or 'LP' lamps) based on the above referenced paper. For
example,
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the fluence for Aspergillus niger (ATCC 32625) for a 1-log reduction in the
Source
article is 116 mJ/cm2 and for a 2-log reduction in 245 mJ/cm2 , so the
'fluence
multiple' to go from 1-log to 2-log is 245/116-2.11. The tabular data in the
paper
specifies "Fluence (UV dose) (mJ/cm2) for a given log reduction without
photoreactivation."
1003711 The analysis of the data shows that the incremental LP fluence for a
given
microorganism to go from 1-log to 2-log is only the same as going from 2-log
to 3-
log about 25% of the time, based on the 304 microorganisms (aka 'data points')
in the
Source article having LP data for 1, 2, and 3-log reductions out of the 337
having LP
data for at least a 1-log reduction.
1003721 Note also that the data is based on disinfection in water, whereas
surface
disinfection requirements may be higher or lower, depending upon microorganism
type, and Figure 2 also captures this data from Table 4.1 of Ultraviolet
Germicidal
Irradiation Handbook - UVGI for Air and Surface Disinfection (ISBN 978-3-642-
01998-2). Of course, these data should also be used to obtain a sense of
general
direction, as they have their own caveats since they were based on results
from
different studies, etc.
1003731 All the tabular data from the Source article were used except for any
LP
tabular entries that had qualifiers (e.g., ¨, <, and >). These were excluded
since the
'fluence multiples' could not be calculated consistently. There are six
summary tables
on the right. The topmost summarizes all microorganism types, while the tables
below
that provide a summary for each specific microorganism type (Spore, Bacterium,
etc.). The columns show for a given type of microorganism, the average fluence
multiple required to go from a 1-log to a 2-log reduction (1->2 log), etc.
Table entries
of #N/A indicate the data was not available (or calculation was not
applicable).
1003741 As cited herein, objects to be irradiated comprise complex surfaces,
and so
there is a big difference between a laboratory collimated light test setup and
a UVC
tunnel in a strawberry production processing facility. Two excellent articles
on the
complexities involved are Simulation of UV-C Intensity Distribution and
Inactivation
of Mold Spores on Strawberries, and their follow-on work Simulation of UV-C
Dose
Distribution and Inactivation of Mold Spore on Strawberries in a Conveyor
System.
These will be discussed elsewhere herein.
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003751 In shadow measurements, the fog increases the overall irradiance in a -
monotonic fashion (there may be a local maximum around d=4.69", which warrants
further study), in proportion with distance. The increased fluence re:
shadowing,
whether visible light in Figure 14 or the LTVC light in Figure 27, show gains
of a
factor more than 2 (fog/no-fog) relative to a no-fog condition. As shown in
Figure 2
(citing Fluence (UV Dose) Required to Achieve Incremental Log Inactivation of
Bacteria. Protozoa. Viruses and Algae), a factor of 2 increase in fluence
corresponds,
for many pathogens, to more than 1-log incremental reduction.
1003761 d) The effects of humidity on disinfection - It is also important to
understand the effects of humidity on disinfection (other than from the dry
fog
scattering and evaporative effects discussed herein).
1003771 See, e.g., "Of the physical factors that might influence UVGI lamp
performance, air temperature and flow rate, lamp design, and ballast design
were
found to be most significant. Isolated changes in humidity had a measurable
but very
small effect on lamp irradiance ... It is critical to understand the effect of
humidity on
the various organisms. The literature is contradictory on the subject. The
physical
factors work has shown that the lights are not affected This makes it critical
to clarify
the impact of humidity on the organisms. ... Humidity and organic matter were
shown
in sections 4.1.1 and 4.1.2 to have protective effects that would be difficult
to
distinguish from natural variation in an environmental organism, and
significant
variation should be expected. Resistance variations between strains of the
same
organism have the potential to be substantial. Very little work has been
done."
Defining The Effectiveness Of UV Lamps Installed In Circulating Air Ductwork
(2002).
1003781 "A possible reason for the higher transfer efficiency under high
relative
humidity observed in our study was that the high humidity prevented the
inoculum
from drying, resulting in greater transfer efficiencies." Transfer Efficiency
of Bacteria
and Viruses from Porous and Nonporous Fomites to Fingers under Different
Relative
Humidity Conditions. -The effect of relative humidity (RH) on the UV
susceptibility
of microorganisms has been studied for decades but no general explanation has
emerged that applies to all microbes, and no predictive methods have
previously been
developed. Most bacteria tested tend to experience decreased UV susceptibility
at
high RH, but some show the opposite effect, or no significant effect at all.
Viruses
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show mixed results, with some experiencing a small increase in UV
susceptibility
with increasing RH. Webb (1965) found that airborne Pigeon pox virus was
extremely
hardy and resisted inactivation from variations in RH, while Rous sarcoma
virus was
largely inactivated at 30% humidity. Both viruses survived well at 80% RH.
Spores
show little, if any, response to changes in RH, although data is still quite
limited."
Ultraviolet Germicidal Irradiation Handbook UVGI for Air and Surface
Disinfection
(ISBN 978-3-642- 01998-2).
1003791 e) Benefits to improvements in UVC uniformity - In the direct-view
measurements, the fog reduces the overall irradiance in a monotonic fashion,
inversely with distance. However, this reduction comes with an increase in
fluence
uniformity as cited herein. The benefits are cited in Simulation of UV-C
Intensity
Distribution and Inactivation of Mold Spores on Strawberries: "There are many
reasons a uniform irradiation dose is desired for UV-C treatment. Firstly,
uniform
dose distribution is needed to achieve an even level of inactivation.
Secondly,
overexposure to UV-C could degrade the quality of the fruits. Thus, the range
of dose
intensity should be as narrow as possible to avoid applying too much
radiation.
Potential damage to strawberries under high UV-C close includes browning of
the
calyx (Lammertyn et al., 2003). Thirdly, the inactivation effect of UV-C on
fruits is
found to increase with UV-C dose initially but then begins to diminish after
exceeding
a certain threshold (Nigro et al., 2000; Stevens et al., 1996). Hence,
delivering the
optimal dosage with uniform dose distribution is important to successfully
implement
UV-C treatment of fruits. ... To determine the optimal horizontal distance
which
provides the most uniform dose distribution, the coefficient of variation (CV)
was
calculated. CV is a normalized measure of
dispersion of a probability distribution and can be calculated as follows. CV
= alp
[Eq. 9] where u is the standard deviation and p is the mean intensity of
surface
incident radiation (W m-2)." CV is also discussed in Protocol for Determining
Ultraviolet Light Emitting Diode (UV-LED) Fluence for Microbial Inactivation
Studies, "a CV of 6.7% was determined to be the maximum CV value to obtain a
uniform irradiance distribution". Note the calculation is based on a finite
number of
samples since the metrology does not have infinite resolution. Now, in the
field of
flat panel displays, luminance uniformity requirements are applied to both
small areas
and large areas of the same display. See, e.g., Human Factors Evaluation of
Portable
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Electronic Devices in Tactical Aircraft, citing a military specification,
where" Large
area uniformity guidelines arc as follows: "The difference in luminance
between any
point and the average within any circle whose diameter is one-fourth the
display 's
minimum dimension shall not exceed +20% of the average value. Total variation
across the display shall not exceed 40%. ... Small area uniformity
guidelines are as
follows: The difference in luminance between any point and the average within
any
mm circle shall not exceed +10%."
1003801 Note also that CV is applied in the application of a flat Petri dish,
and the
small area and large area uniformities for flat panel displays are obviously
applied to
10 flat surfaces as well. What about a complex surface like a strawberry
under UV
irradiation? How about a random assortment of strawberries in a UV tunnel?
1003811 Previous work in the food industry have established baseline
configurations that can be further enhanced by the instant invention, as cited
in
Simulation of UV-C Dose Distribution and inactivation of Mold Spore on
Strawberries in a Conveyor System: "(2) Uniformity evaluation - Uniformity of
UV-
C dose distribution on the surface of strawberries was evaluated using the
coefficient
of variation (CV), which was a normalized index of dispersion of a probability
distribution. Results and Discussion ¨ (1) Uniformity evaluation - In order to
evaluate
the uniformity of UV-C dose distribution on the surface of strawberries, the
radiation
simulations were carried out using four configuration models. The UV-C
treatment
time was fixed at 7 s, the conveying speed and mesh sliding steps were fixed
at 0.1 m
s...1 and seven, respectively. This meant that the incident UV-C intensity was
calculated independently at seven time-dependent positions with 0.1 m sliding
distances, and the irradiation time for each position was 1 s. The total
irradiated UV-C
dose distribution was estimated by accumulating incident UV-C dose on the
surface
of strawberries at seven time-dependent positions. The results of the
simulation are
presented in Fig. 5. The frequency polygons of incident radiation dose on the
surface
of strawberries can be recognized visually." This, of course, is a simulation.
Actual
measurements, e.g., in the field of UVC surface disinfection, would best use
actual
inoculation, irradiation, stomaching, etc. as described, e.g., in Ultraviolet-
C light
inactivation of Escherichia coli 0157147 and Listeria monocvtogenes on organic
fruit
surfaces. However, a system with good uniformity may also have small spikes in
a
beam outside of the sample points that over-irradiate and damage the quality
of a
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strawberry. Other wave energy sources, e.g., applied to non-disinfection
applications
may also have nuances that require careful consideration when determining a
meaningful uniformity number. Note that an approach using metrology that could
catch these spikes and provide high fluence resolution is taught herein using
the
inventive dosimetric avatar. These avatars could be constructed for all wave
energy
sources (EM, EL, QP) with appropriate selection of relevant dosimetric
materials.
[00382] With respect to a scattering field, note that the distribution of
scattering
elements tails-off and can be altered by air currents during the testing, and
so this adds
another layer of complexity to the uniformity determination. Further, the beam
profile
of the wave energy source and the geometry of the test setup would influence
the
determination, and thus standard test setups must be defined like they are in
the UVC
disinfection and flat panel display industries. Generally, these
determinations are
made by organizational expert committees to ensure all stakeholders have a
voice and
the appropriate amount of confirmatory testing has been completed.
1003831 It is important to note that in both the shadow and direct-view
measurements, scattered light that misses the upper UVC sensor is not
absorbed, but
simply redirected in other forward trajectories that may strike another
surface to
disinfect it (or for visible/N1R light in a greenhouse, light may strike
another leaf
portion to enhance photosynthetic growth).
1003841 By optimizing (testing, CFD, etc.) the number concentration (e.g.,
with a
larger piezo/ultrasonic dry fog atomizer system), the number of UVC sources
and
their locations and beam profiles, etc., the instant invention can improve the
efficacy
in a variety of applications across the electromagnetic spectrum.
1003851 As an aside, more information is available in the incorporated-by-
reference provisional filings on EM, EL, and QP wave energy sources,
scattering
characterization, as well as dosimetry and dosimeters, including commercially
available devices.
1003861 Dosimetry and Actinometry for use on a conveyor belt traveling through
a
UVC tunnel - Correlations between dosimetry and log-reduction can be seen,
e.g., in
Inactivation Characteristics and Modeling of Mold Spores by UV-C Radiation
Based
on Irradiation Dose. Fluence/dosage can be measured in a number of ways, e.g.,
via
traditional electroopti cal radiometers, photochromic and radiochromic
indicators, and
3D volumetric dosimeters, all citied previously. These are well understood and
their
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use in the instant invention, in addition to the use of newly proposed
approaches are
discussed below. Note that some approaches are reusable such as electrooptical
and
those based on reversible photochromic pigments/dyes. The reuse is a benefit;
however, the data must be captured quickly as it is effectively erased over
time. Thus,
the advantage, e.g., of dosimeter cards that use irreversible photochromic
pigments/dyes, however, there is the expense of continually purchasing new
devices.
As an aside, the specific photochromic chemical(s) used by the makers of
dosimeter
cards have not been found in the literature. The instant invention also
proposes non-
traditional/new methods of dosimetry.
1003871 Non-traditional chemical pigments/dyes - Irreversible photochromic
pigment that changes from colorless to purple is available from New Color
Chemical
Co., Limited (Xiamen, China), see Irreversible Photochromic Pigment Technical
Data Sheet (New Color Chemical Co.). See also US20140038305 Articles and
methods for the detection and quantification of ultraviolet light. Cyanotype
and
SolarFast dyes are known to change with UV exposure: Cyanotype changes from
clear to 'Prussian blue' after UV exposure, and SolarFast dye is available in
a wide
variety of colors with varying color changes upon ITV exposure These are avail
able
from Rupert, Gibbon & Spider, Inc., manufacturers of Jacquard Products,
(Healdsburg, CA). Both Cyanotype and SolarFast dyes are marketed for use on
natural fibers, however they can be used with nylon "Nylon performs a lot like
silk
and they both hold really tightly to the fiber. That means you really need to
wash
properly and thoroughly after exposure." (private communication with Jacquard
Products 15-Mar-2021) even though its use on nylon is not mentioned publicly
by
Jacquard Products, and numerous sources say to avoid fibers that are not
natural.
1003881 Glow phosphors - Also known as long-persistence phosphors, these
include commercially available material such as SrA1204:Eu,Dy, and are
excitable
across the UV spectrum, including by UVC. They are commercially available in
encapsulated and unencapsulated form, see e.g., Techno Glow (Ennis, Texas),
the
former offering protection from the environment albeit at a slight loss in
performance. The brightest phosphor powder from Techno Glow is their green
unencapsulated Strontium Aluminate Europium Dysprosium SKU P02-GRN-M, with
stated emission intensities (excitation conditions not specified) as follows:
Immediate: 93,000 mcd/m2, 1 Minute: 6,000 mcd/m2, 10 Minutes: 940 mcd/m2, 60
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Minutes: 207 mcd/m2 The particle size is said to be < 100 microns, and thus
provides a high resolution coating.
1003891 A challenge with using these phosphors is the brightness decay,
comprising a very rapid initial decay, i.e., once an object is irradiated with
UVC, the
peak intensity emission from the phosphor decays rapidly, and so is difficult
to
capture by a measurement device if the object must be moved from the
irradiation
tunnel to a measurement area. In addition, the phosphors must be attached-to
or
incorporated within an object without negatively affecting the UVC
transmittance to
the phosphor from the UVC source, and from the phosphor to the measurement
device.
1003901 One simple method is to coat phosphors on an object using a spray
adhesive and then add a protective encapsulant/overcoat. In some instances, it
may
be desirable to include some absorbing material (e.g., neutral density carbon
black)
in the overcoat to enable use in very-high UVC irradiances such that the
phosphors
are not saturated, although the optical density should be consistent across
the object's
surface (requires a homogeneous dispersion of carbon black and being
consistent in
the coating thickness)
1003911 Another would be to disperse the phosphors in a UVC encapsulant that
is
then coated on the object (the encapsulant can be loaded with carbon black as
cited
previously).
1003921 Note that the emission brightness of these phosphors changes with
"Glow
Crystal Particle Size, Loading Content, Transparency of Resin, Excitation
Intensity,
Exposure Time" (Source: FAOs ¨ GlowStop.com, GloTech International, Auckland,
New Zealand). A deeper, technical perspective can be found, e.g., in Long
persistent
phosphors¨from fundamentals to applications. Note that the combination of
excitation intensity and time can be consider a dosage, and so thus the
prospect of
using glow phosphors as a reversible/reusable dosimeter.
1003931 To use these phosphors, the decay curves at various excitation
intensities
can be characterized by sending a phosphor-coated test coupon through a UVC
tunnel along with the objects to be disinfected (or their avatars). A circular
coupon
would be placed below gradient neutral density filter such as Circular Linear
Variable Metallic Neutral Density Filters from Newport Corporation (Franklin,
MA),
available in optical densities from 0 to 1, 2, or 4. Further, a puck-style UVC
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radiometer is placed adjacent to the coupon to measure the raw intensity from
the
UVC lamp(s), representing the intensity at the phosphor coating. Intensities
are
measured from the object (e.g., a phosphor coated strawberry or its avatar)
and at the
same time from various locations across the coupon and the time-history from
the
radiometer puck as it too traversed the tunnel. One can then correlate an
intensity
measurement on the surface of the object to a dosage, thus compensating for
the
decay curves of the excited phosphors. Even without the radiometer, the
approach
can still provide information on the relative irradiation across the surface
topology of
the object which can be captured via one or more visible light sensors, e.g.,
via one
or more cameras using photogrammetry.
1003941 In one preferred embodiment, as mentioned previously, glow phosphors
(Green (#1 Choice), SKU P02-GRN-M0001Z from Techno Glow, Ennis, TX) were
sprinkled on a fake plastic strawberry after applying E6000 spray adhesive and
smoothing with an acid/flux brush. Excess was removed by gentle tapping, and
after
curing the coated strawberry was placed in a HomeSoap UVC chamber, and after
1
minute, the door was opened, and an obvious glow was emanating from the
phosphor
coating For furtherprotection, a low viscosity T.TVC encapsulant such as
MasterSil
151 can then be conformally coated in a thin layer to avoid excess UVC
absorption
Exemplary excitation, emission, and decay curves are shown in Roles of Eu2+.
Dy3+
Ions in Persistent Luminescence of Strontium Aluminates Phosphors.
1003951 Lightfastness - "Lightfastness is a property of a colourant such as
dye or
pigment that describes how resistant to fading it is when exposed to
light.[1][2][3]
Dyes and pigments are used for example for dyeing of fabrics, plastics or
other
materials and manufacturing paints or printing inks. The bleaching of the
color is
caused by the impact of ultraviolet radiation in the chemical structure of the
molecules giving the color of the subject. The part of a molecule responsible
for its
color is called the chromophore.[4][5] Light encountering a painted surface
can
either alter or break the chemical bonds of the pigment, causing the colors to
bleach
or change in a process known as photodegradation.[6] Materials that resist
this effect
are said to belightfast." Lightfastness Wikipedia.
1003961 A well-known standard tester for measuring lightfastness is the Fade-
Ometer, e.g., see the brochure Atlas Ci3000F Weather-Ometer and Fade-Ometer.
Lightfastness of inks ¨ see, e.g., Light fastness of printing inks - A review.
The
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general lightfastness of inks and dyes are described in Materials Information
and
Technical Resources For Artists - ASTM and Lightfastness of Media. Since the
need
is to quickly show chromic variations in response, e.g., to UVC light,
materials with
poor or very poor lightfastness (Lightfastness categories IV and V.
respectively) are
favored for the instant application. See, e.g., Technical Pigments and Pre=
arations for
Plastics (Sun Chemical), especially pigments with poor colorfastness and high
temperature stability ( e.g., suitable for incorporating in 3D printing
filaments) such
as Sunbrite Orange 46 with light stability of 2 (1 being the poorest) and
heat
stability of 300 C, and FDA approved pigment for cosmetics, SunCROMATm FD&C
Yellow 6 Al Lake with a light stability of 2 and a temperature range up to 275
C. It
is important to note that FDA food grade colorants should be considered for
use on
food production lines, see, e.g., How Safe are Color Additives FDA. Color
additives are also available from IFC Solutions (Linden, NJ). Graphs showing
rapid
photodegradation of commercial inks in response to a carbon-arc lamp can be
found
in Figures 9 & 31 of Study of the Photodegradation of Commercial Dyes.
1003971 Tnemec (Kansas City, MO) makes a "... colorant which fades from
purple to clear The fugitive colorant, Series 44-500 Ski p-Safrm
. . Added in the
field to Tnemecs clear urethane topcoats, Skip-Sal is a translucent-colored
tint that
"dyes" the urethane topcoat purple, allowing the applicator to clearly see the
work in
progress. This helps prevent skipping of areas, aids in the application of
correct film
thickness and makes apparent any runs or sags. Within four to 72 hours?
exposure to
direct and indirect sunlight, the purple tint disappears ...". Fugitive Dye
Helps
Contractors Apply Coatings Evenly WaterWorld. The data sheet cited US5548010
Color dissipatable paint. It describes various chemistries that comprise a
"color-
dissipatable paint additive that, because it has a light unstable dye therein,
when
mixed with paint, provides a second color that dissipates within a reasonable
time
frame, generally from hours to a few days ... it is well known that some dyes
have
poor light stability characteristics. Two typical dyes of this category are,
FD&C#2
blue (indigotene), and Basonyl green NB-832 (triarylmethane). ..." Note that
this
of course reference to normal sunlight, not, e.g., the intense U VC in a
disinfection
tunnel. It is contemplated that such a fugitive colorant can be added to a
LTVC
transparent encapsulant, a thin mildly UVC-absorptive encapsulant, molded
component or a 3D printed filament.
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003981 Photopolymers - "3D printers of this type use a UV photo cured resin
for
the build material. At the completion of the 3D printer's build cycle, the
parts need to
be post-cured with UV light to finish the part" as cited in the brochure for
the helix
cure 12OTM UV Curing Chamber, 2018-06-10-helix-cure-120, from Strategic 3D
Solutions, Inc. (Raleigh, NC). Thus, for the instant invention, e.g., a
strawberry can
be 3D printed, and then placed in a UV tunnel, and the degree of UV post-cure
is an
indication of the dosimetry. Insufficient UV post curing manifests itself,
e.g., in
shape distortions as discussed Mechanics of shape distortion of DLP 3D printed
structures duiingUV post ¨ curing. Such distortions can be sensed by 3D
scanning,
e.g., photogrammetry. Note that a common wavelength for UV photo curing is
405nm, and thus this approach is most easily suitable for use in systems that
utilize
405nm violet-blue light, e.g., for pathogen reduction, see, e.g., 405 nm light
technology for the inactivation of pathogens and its potential role for
environmental
disinfection and infection control, Disease Suppression in Greenhouse Tomato
by
Supplementary Lighting with 405 nm LED.
1003991 Food safety ¨ food contact with dosimeters - Food safe coatings ¨
certain
photochromic materials, like many inks, may not be listed with FDA (or equiv.)
as
food safe. First note, however, that a dosimeter need not be deployed when
food is
running through a production line UVC tunnel, so concerns regarding FDA
compatibility of dosimeter materials can capitalize on this flexibility.
Second, if
running alongside food, there are analogous applications where food safe
protective
coatings are used: "Inks and coatings that do not have direct food contact are
not
regulated; as long as there is a "functional barrier" between the food contact
side and
the ink or coating, and the inks and coatings do not migrate to the food
contact side
during various steps in the process. It is the responsibility of the packaging
manufacturer to determine if the construction meets the definition of a
functional
barrier." Food Packaging - A Guide to Best Practices for Print. "Incidental
contact
substances are those where contact is not intended nor is it continuous, such
as
involving food processing equipment. Food packaging printing inks and coatings
may
be indirect food additives as they could have direct, indirect or incidental
contact with
food. 3. Barrier Coatings Stop Migration FFDCA recognizes that a functional
barrier
can prevent a substance from migrating into and becoming a component of food.
Under 21 CFR 170.3(e) "If there is no migration of a packaging component from
the
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package to the food, it does not become a component of the food and thus is
not a
food additive." Under these criteria the substance is not subject to
regulation,
however, packaging end-users are responsible for extraction testing to assure
compliance." 7 Essentials of FDA Food Contact Coatings = Cork Industries.
1004001 FEP (fluorinated ethylene propylene copolymer) ¨ 856G-200 is a 2 mil
thick FDA compliant coating as disclosed in Teflon FEP Coatings (Intech
Services,
Inc., Newark, DE). FEP is well known for a high degree of UVC transparency,
often
used to encase LP mercury bulbs in UVC disinfection systems. Intech claims FEP
coating thicknesses down to 0.5 mil in thickness. FEP coating cure
temperatures are
fairly high, between 575 F - 700 F (301 C to 370 C). "FEP heat shrink tubing
requires approximately 420 F 50 F (215 C 10 C) to initiate shrinkage"
with
shrink ratios of 1.3:1 and 1.6:1 and standard minimum wall thickness starting
at 8
mils. Zeus-Catalog-G V IRI, Zeus Industrial Products, Inc. (Orangeburg, SC)
1004011 Parylene C ¨ "a food contact approved substance and is registered
through
the FCN nr 001777 at the US Food and Drug Administration." Comelec SA (La
Chaux-de-Fonds, Switzerland). Much higher absorption in UVC than FEP; details
can
be found in Parylene Optical Properties Why Your Competitors See Parylene in a
New Light - VSi Parylene. Note however that Parylene C is deposited at room
temperature (see e.g., Parylene Deposition Process _ Specialty Coating
Systems,
Specialty Coating Systems Inc., Indianapolis, IN), and thus if the UVC
intensity is
high enough whereby the Parylene C UVC absorption still allows sufficient
exposure
of photochromic materials, then this becomes an option for UVC dosimetry.
1004021 Addition of absorbers to enable use in higher intensity (UVC) fields -
In
some applications, the desire is only to ensure the UVC dosage meets a minimum
level across the surface of an object. In such cases, additional absorption
(e.g., carbon
black additives, neutral density filters, etc.) can be used to ensure a
dosimeter is not
saturated before it can register the appropriate dosage level. Thus, if the
natural state
of, e.g., a chemical actinometer is too sensitive for indicating the minimum
dosage,
additional absorption can be added. Simple detectors may then surround the
object
after exposure, set to trigger if a threshold chromatic response (depending on
the type
of actinometer material) is reached, indicating less than the minimal dosage
after
irradiation, after which an alarm causes one or more remediating operations
(e.g.,
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increase in UV intensity, slowdown in belt speed in a UVC tunnel, change to
dry fog
flow rate, etc.).
1004031 Carbon black and others are cited in UV Degradation Effects in
Materials
¨ An Elementary Overview. UV absorbing carbon black materials for use in
manufacturing are cited in Specialty Carbon Blacks For Plastics from Cabot
Corporation (Billerica, MA). A technical analysis of carbon black loading vs
absorbance in the UVC wavelength range is disclosed in Spectroscopic Studies
of
Polyester ¨ Carbon Black Composites. D&C Black No. 2 ¨ "... high-purity carbon
blacks approved by FDA, including ... high-purity furnace black, which is
approved
for use in food-contact polymers ( 178.3297 (21 CFR 178.3297))." Federal
Register -
Vol. 83, No. 110 - Thursday, June 7.. 2018 - Rules and Regulations. Suitable
commercially available FDA-approved carbon blacks are manufactured by Cabot
Corporation (Billerica, MA), Specialty Carbon Blacks for Food Contact
Applications
in Plastics (Cabot). These carbon blacks can thus be used in dosimeters on
food
processing lines. Certain food colorants exhibit absorption in the UV,
enabling their
use on/within dosimeters on food processing lines. See, e.g., Characterization
and
Measurement of Anthocyanins by UV-Visible Spectroscopy comprising a
representative spectrum therein.
[004041 Dosimetric avatars - A dosimetric avatar is a 3D object constructed to
record surface irradiation that correlates with how a predetermined second
object
would react (e.g., a strawberry's surface being disinfected by UVC). This is
different
than a 3D volumetric dosimeter as previously cited, which are meant to record
the
dosage throughout the volume of an object (e.g., mimicking a patient's organ
to
record the volumetric distribution of therapeutic x-rays).
[00405] In one embodiment, these novel dosimeters can use non-living materials
to indicate fluence (e.g., the chemicals, phosphors, etc., as cited herein).
In another
embodiment, they are inoculated with pathogens as well comprising the non-
living
material. In this case, the avatar provides the shadowing function as well as
an
indication of the fluence around the pathogens.
1004061 In one embodiment, a dosimetric avatar is constructed such that a
first
surface portion creates a shadow on a second surface portion when irradiated
from a
source of wave energy external to the dosimetric avatar ( e.g., a UVC,
Visible/NIR, e-
beam, etc.), the shadow geometry modeled after a shadow geometry on the second
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object (e.g., the achenes on a strawberry), and the shadowed surface portion
constructed of a material that changes its properties when irradiated such
that the
changed properties correlates to a dose ( e.g., using dyes that are used in
dosimeter
cards). The correlation of the changed properties is constructed in the form
of one or
more of algorithms, mathematical formulae, and lookup tables. For example,
dosimetry cards react to fluences by a change in color/tone. This change can
be
correlated to a fluence by characterizing the cards with a calibrated setup
and known
fluences in a controlled fashion.
1004071 Note that the dosimetric avatar is not the same as attaching an off-
the-shelf
dosimetric decal to an N95 mask, and then irradiating the mask with its decals
as the
decals do not capture micro-shadows that would be created, e.g., by the fibers
of the
mask. The avatar provides an additional level of fidelity. This approach may
or may
not use the original object as part of the avatar.
004081 As background, see, e.g., "... Radiochromic films were attached to
various
surface locations on 12 apples ("Fuji") to study the uniformity of UV-C
exposure."
Radiochromic film dosimetry for UV-C treatments of apple fruit and "We exposed
PCI1 indicators located on exterior and interior N95 surfaces to sub-
saturating UV-C
treatments (Fig 3B-3D)." Quantitative UV-C dose validation with photochromic
indicators for informed N95 emergency decontamination. In these approached,
paper
dosimeters are placed on 3D objects, providing the irradiance around the
outside
surface of the object, although not likely conforming exactly to any sharp
curvatures
of the original surface. Also, the texturing of the original object is not
replicated in the
decals, nor were decals placed just below the surface to indicate canyon wall
effects.
1004091 Manufactured objects can be made to act as avatars for real objects
(made
via 3D printing, machining, etc.). Note that in any of the approaches
disclosed below,
the avatar and/or the sensors can be moved to temporally sample the fluence as
the
dosimeter traverses, e.g., through a UVC tunnel. While the Dosimetric Avatars
have
been disclosed for use, e.g., with the dry fog scattering also disclosed in
the instant
invention, such avatars can be used with any irradiation system, including
more
traditional non-fog UV systems.
1004101 UVC material compatibility must be understood before selected a host
material. A number of references have been previously cited in the instant
invention.
More recent publications include Damage to Common Healthcare Polymer Surfaces
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from UV-C Exposure and Interactions and damage of surfaces by light. Note that
the
fluence received by the host material of the avatar may or may-not be
sufficient to
bias the dosimetry (unless the degradative effects, in-full or in-part, are
being used for
dosimetry), but should be considered. Note that an avatar need not react to
irradiation
with the same time constant as how the real object reacts to the irradiation.
However,
it is important that there is a method by which the two can be correlated,
e.g., by use
of a scaling factor/function derived from actual test trials accompanied by a
separate
radiometer. Similar time constants can be useful, however, in some cases like
real
time mock production trials.
1004111 Shadow resolution:
1004121 a) A photomicrograph of a strawberry (see ID number SS2259206 at
Science Source, New York, NY) shows that the achenes (contains the seed) on
the
surface of the strawberry is roughly on the order of 500p. x 1000 and sits
100011
below the outer surface of the strawberry. Thus, any dosimetric feature added
to a
strawberry (or an avatar thereof as discussed herein, which for example is a
realistic
copy of a strawberry that has been dyed with an ink that has dosimetric
properties)
should capture this natural shadowing or at least the aspect ratio defining
the canyon
wall effect (also discussed herein). Further, a strawberry avatar created,
e.g., by 3D
printing, should be made on a printer having resolution in x, y, and z,
sufficient to
preserve natural shadowing for portions of the avatar that will be examined
for
dosage. A discussion of 3D printer resolutions from 2015 can be found in What
Resolution Can 3D Printers Print.
1004131 b) 3D printing (or any additive/subtractive manufacturing process or
combinations thereof) of objects must also consider the surface roughness of
the
target in order to understand threshold feature sizes that tend to trap
microbes. In
Surface modifications for antimicrobial effects in the healthcare setting - a
critical
overview, it states in part "However, the assumption 'the rougher the surface,
the
worse the hygienic status' is somewhat simplistic, although many publications
make
this type of claim. Cells are easily removed from 'smooth' surfaces, but they
may be
retained within features approximating in size to that of the cells. In larger
features,
the cells may again be relatively easily removed. Typically, surface
topography is
measured by the Ra-value, defined as 'the average departure of the surface
profile
from a center line'. Other parameters are also used, but the Ra-value is the
most
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popular in the microbiology literature. An Ra-value of 0.8 pm is often deemed
indicative of a hygienic surface." So, if the intent is to be wholly faithful,
e.g., to a
real strawberry, then the Ra-value of a strawberry avatar should mimic that of
the real
strawberry. Note that UVC wavelengths are about 0.25 gm, so they are much
smaller
than the smallest strawberry feature size and therefore are not fundamentally
limited
in their ability to reach into the shadowed areas. Should smaller wavelengths
be
required, VUV, x-rays, gamma rays, and even electrons or ions (whose de
Broglie
wavelength, a function of accelerating voltage, can be on the order of
nanometers) and
other particles can be used. "... the momentum of a photon can be expressed as
p=h/X.
This equation shows that the photon wavelength can be specified by its
momentum:
X=h1p. De Broglie suggested that material particles of momentum p have a
characteristic wavelength that is given by the same expression, ?=h/p. Because
the
magnitude of the momentum of a particle of mass m and speed u is p=mu, the de
Broglie wavelength of that particle is5 X=h1p=h1 mu . 5The de Broglie
wavelength
for a particle moving at any speed u is k=hlymu, where T=[1-(u2/c2)]-1/2." The
velocity created by acceleration in a voltage potential, AV, between two
parallel plates
is given by the formula u =[ 2gAV/m 11/2, where q is the charge, m is the mass
of the
particle, and u is the velocity. The above extracted from PHYSICS for
Scientists and
Engineers with Modern Physics (ISBN 978-0-495-11245-7)
1004141 c) 3D models ¨ models are available for various foods and other
objects,
such as the Strawberry 3D model (Model ID #976725 from Humster3D) via the
portal
CGTrader (Vilnius, Lithuania and New York, NY). A one-time (royalty free)
upfront
license of $49, downloadable in the following formats: *.max (3ds Max 2008
scanline), *.max (3ds Max 2008 vray), *.thx, (Multi Format), *.obj (Multi
Format),
*.3ds (Multi Format), *.mb (Maya 8.5), *.lwo (Lightwave 6), *.c4d (Cinema 4D
11).
The polygon mesh model has 358,220 polygons and 360,125 vertices, providing a
very-detailed surface texture, where surface texture is very-important for
high fidelity
dosimetric avatars. Note that not all models on the portal have this level of
detail, yet
some of these lower resolution models may be suitable for gross testing.
1004151 d) A 3D model may be modified to add surface roughness as described in
Intentional Design of Surface Roughness for Orthopedic Parts nTopologv. A 3D
printed strawberry may also be further post-processed to add surface roughness
features smaller than the resolution available on the printer. Some techniques
used to
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add micro roughness to materials (e.g., painting, coating, acid-baths) is
discussed,
e.g., in Influence of topographical features on the surface appearance
measurement of
injection moulded components. In Combination of laser surface texturing and
DLC
coating on PEEK for enhanced tribological properties, the authors state in
part "...
PEEK surfaces modified via laser surface texturing (LST) combined with DLC
coating. An ultrashort-pulse laser was used in order to pattern a hexagonal
array of 33
pm in diameter dimples onto the PEEK surface. The depth of dimples was varying
(2,
12 and 21 pm) as well as the dimple density (10, 30 and 48%)." See also Effect
of
surface roughness on the ultrashort pulsed laser ablation fluence threshold
of zinc and
steel, which starts "Laser ablation is a subtractive micromachining technique,
which
can be employed to improve the surface functionality of a product by applying
a laser-
induced texture to the surface [1]. It is a flexible and precise manufacturing
process
compared to other techniques, such as electric discharge texturing, chemical
etching,
shot blasting and electron beam texturing [2]." Companies that provide
texturing
equipment/services include: Comco Inc (Burbank, CA) ¨ MicroBlasting;
Lightmotif
(Enschede, Netherlands) - laser microtexturing, Standex Engraving Mold-Tech
(Salem, NH) ¨ chemical and laser texturing The impacts of surface roughness in
UVC irradiation systems for a variety of foods is discussed, e.g., in
Ultraviolet-C light
inactivation of Escherichia coli 0157-H7 and Listeria monocytogenes on organic
fruit
surfaces, Pulsed light processing of foods for microbial safety, Applications
of Pulsed
Light Decontamination Technology in Food Processing - An Overview,
Understanding The Factors Affecting Microbiological Quality Of Wheat Milled
Products - From Wheat Fields To Milling Operations, Bactericidal effect of
intense
pulsed light on seeds without loss of viability, Feasibility Study Of Surface
Applications For Flashblast Radiation In The Food Industry, as well as include
the
shadowing due to the food container as discussed in Aseptic Processing and
Packaging of Particulate Foods.
1004161 e) Another surface feature nuance to be considered (in accurately
emulating the microbial retention on object avatars) is the effect of object
feature size
on microbial movement, e.g., in The Effect of Topography on Surface Behavior
of
Pscudomonas aeruginosa, it states in part "We found that there was a threshold
feature
size of 1-2 gm at which bacterial surface motility is drastically impacted.
This
suggests that bacteria in the shadow of a strawberry achenes may find it
difficult to
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move. See also The Effect of Surface Topography on the Retention of
Microorganisms. Note that mean diameters of airborne microbes are shown in
MERV
Filter Models National Air Filtration Association and can be roughly
summarized as
follows - viruses. .02¨.22 pm, bacteria: .17-3.1 gm, fungi : L4-17.3 gm.
[00417] f) In an exemplary embodiment, lower resolution dosimetric/printed
features are employed to fabricate object avatars to ascertain first order
effects, which
in fact may be wholly sufficient for certain applications (in addition to
being more
cost effective to produce).
[00418] g) Note that a non-limiting, wide variety of objects (fruits,
vegetables,
whole plants with exposed parts (one or more of
leaves/roots/flowers/fruits/etc.),
bottles, packaging materials, N95 masks, etc.) are contemplated for use with
the
instant invention.
[00419] (1) 3D printing (an example of additive manufacturing) - Replication
of
natural surface textures so that the surrogate does not add more shadowed
areas,
thereby making the test results overly conservative. The matter of 3D printer
resolution is discussed in What Does Resolution Mean in 3D Printing_ Formlabs.
[00420] (2) Multi-axis CNC (an example of subtractive manufacturing) - The
fabrication of dosimetric avatars can be made via 5-axis CNC machines in a
wide
variety of materials, including wood that can be dyed with dosimetric
material. See,
e.g., 5axisworks Ltd. (London, England), with their 5AXISM.AKER having working
volumes 400mm on a side and larger, mechanical resolution of 36 microns (XYZ)
and
.034 degrees (BC-axis), electronic resolution of 4.5 microns (XYZ) and .0041
degrees
(BC-axis), and mechanical repeatability of 50 microns (XYZ) and .017 degrees
(BC-
axis). See also the Desktop 5-axis CNC Mill from RobotDigg (Zhejiang, China).
Note
that the material can be removed via traditional machine tools such as drills
and/or
custom-cutters like those available from Vexor Custom Woodworking Tools
(Denver,
CO), etc. Laser cutting (and other approaches) are also contemplated, as
disclosed
below. Several exemplary embodiments follow.
[00421] A CNC drilled polycarbonate (PC) plate is an interesting option since
it is
very absorbing in UVC, and thus holes made in a PC plate allow UVC to pass
only if
it is on or near the hole's axis and aligned-with or tilted slightly about the
axis (the
amount dependent upon the hole size and plate thickness) which can be
determined
with simple geometry. This effectively eliminates any biases due to the
plate's UVC
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reflective/scattering properties By selecting the PC plate thickness, hole
size, hole
taper (and other geometric features such as a countersink, etc.) if any, and
hole axis
angle relative to the surface-normal of the plate, only light from
predetermined
directions is allowed to pass through the plate. On the underside of the PC
plate a
dosimeter is placed, either a (permanent) card-type or one or more
optoelectronic
UVC sensors. The hole pattern in the PC plate can be made to maximize the
available
sensing surfaces of an existing card or optoelectronic sensor(s), although
custom
cards/sensors can of course be made. One method of making holes in PC plates
is via
laser drilling, available, e.g., from Laser Light Technologies (Hermann, MO).
Laser
micromachining systems are available, e.g., from AMADA WELD TECH INC.
(Monrovia, CA). Consistent dosimetry requires consistent hole sizes and
surface
finish. Note that the holes can be filled with a UVC transparent encapsul ant
to provide
an environmental seal. An alternative environmental seal would be to use be a
thin
piece of UV grade fused silica (UVGFS) or FEP, followed by the PC plate,
followed
by the card/sensor(s). An environmental seal around the edges of the backside
of the
UVGFS for compressing against the enclosure would then prevent FOD from
entering
the dosimeter and allowing the ITVGFS to be wiped clean after each use.
1004221 An alternative to a PC plate would be a PC tube, or even a custom
molded
part (e.g., in the shape of a strawberry or any other edible/non-edible
object). For
example, PC strawberry halves can be fabricated, with each half having a flat
back-
surface to accommodate a dosimeter card/sensor(s) facing strategically placed
holes in
the PC that pass from the back-surface through to its 3D shaped/textured front-
surface. Alternatively, a PC tube is made with strategically placed holes,
where the
tube is covered in FEP much like the (heat shrink) FEP that is used to
encapsulate LP
mercury bulbs. Dosimetric card(s)/sensor(s) are placed on the inside of the PC
tube,
either adjacent to the inside surface of the tube (e.g., curving the card
around an inner
mandrel that is placed in the tube), at a plane in/near the center of the
tube, or at some
other location in the tube.
1004231 Also, in any of the above, 3D modeling software can be used to
determine
a functional equivalence between holes in a gross approximation to, e.g., a
strawberry.
Since there is a randomness to strawberry surfaces and the geometric path by
which
the points on the surface transit the UVC tunnel, a tube, for example, can be
configured with holes relative to the surface normal of the tube that create a
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functionally equivalent shadow as a real strawberry. In fact, the achenes of a
strawberry can be approximated by a countersunk hole drilled into the outer
surface of
the PC, and then one or more through-holes drilled to sample the UVC from
predefined directions. Note that the 3D modeling approach can be used with any
applicable dosimeter disclosed herein.
1004241 (3) Laminated Object Manufacturing - Fine scale laser cut wood sheets
are
laminated to form a 3D object, see e.g., An Additive Manufacturing Method
Using
Large-Scale Wood Inspired by Laminated Object Manufacturing and Plywood
Technology. This assembly technique can also be made via a CNC router, e.g.,
Snapmaker 2.0 from Shenzhen Snapmaker Technologies Co., Ltd. (Shenzhen,
Guangdong, China); note the modular device can also be fitted to perform 3D
printing
and laser engraving.
1004251 (4) Molded part manufacturing - Molded parts are available from many
3rd
parties, such as fruits/vegetables/plants from Yiwu New Funny Crafts Co.,
Ltd.(
Zhejiang, China), and custom injected molded thermoplastic resin parts as
small as
"grain of rice" with wall thicknesses down to wall sections as thin as 0.010"
from
Piller Aimmco (Washougal, WA) Many more can be found via Thomasnet from the
Thomas Publishing Company (New York, NY), which also is a source for any other
materials and manufacturing services herein.
1004261 (5) Shadow pins - Yet another approach to obtaining a high degree of
dosimetric fidelity is to construct a pin-like dosimeter that presses into the
real object
in order to capture real-life shadowing. The head of the pin can be flat to
receive a
small adhesive-backed dosimeter decal. The pin can be pressed into, e.g., a
strawberry
such that the decal is below the surface and in the shadow of surrounding
flesh.
Alternatively, the head of the pin can be manufactured from a dyeable material
and
resembling, e.g., the achenes of a strawberry, which is then dyed with a dye-
based
dosimetry chemical (or can be electro-optical). The strawberry provides the
general
shape that generates gross shadows due to the convexity of the fruit. The pin
provides
an additional 'micro-shadow' as would an achene.
1004271 In yet another alternative, the head of the pin can be made flat, and
a
micro-shadow-inducing feature can be attached to the top of the pin via a
magnet,
adhesive, screw threads, interference fit, Velcro, etc.
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1004281 Pins like these can be made with heads having various canyon-wall
aspect
ratios that can be selected as appropriate for a given food article (or
other).
[00429] The pin-like feature allows attachment of the dosimeter to objects
that may
be wet and thus not amenable to adhesives. However, adhesives and other
fastening
devices can be used instead of pins as desired. For example, it may be
difficult to
attach a pin to hard objects.
[00430] (6) Host/matrix materials that can be dyed - Note that one needs to
consider many aspects when manufacturing such objects to ensure the desired
level of
fidelity to the actual object ( e.g., a strawberry), e.g.,
temperature/humidity and their
effect on the photochromic and host/matrix materials, the
transparency/reflectance/scatter of the host/matrix material to the incident
radiation,
the coefficient of friction, dimensional stability, overall weight, density
distribution,
center of gravity, moments of inertia, brittleness, coefficient of elasticity,
surface
hardness, porosity, color fastness, etc., both before and after irradiation
(with and
without dry fog).
[00431] (a) Plastics ¨
[00432] (i) Nylon - "Nylon a Polyamide Acid, metal complexes,
disperse
reactive and disperse dyes are the important classes of dyes used in dyeing of
nylon."
Dyeing of Polyamide Fibres. See also FAQ: How to dye nylon or polyamide.
1004331 "Polyamide (PA) ... The FDA approved PA 12 (PA 2200), supplied by
EOS GmbH, was used in this study. ... PA and fillers were first dry-mixed by
shaking
in a plastic bag for 5 min prior to feeding into the hopper. The temperature
profiles in
the barrel were set at 180-200 C from the hopper to the die, with screw
rotating speed
of 150 r/min. The extruded strands were immediately quenched after extrusion
in a
water bath, and were then pelletized. Fabrication of composite filament. A
desktop
single screw extruder (Extruder Version 1.3, Filastruder) was used to
fabricate the
filament from the composite mixture. The pellet was dried in the oven at 80 C
for 24
h. The nozzle temperature was set at 185 5 C until 1.75 0.1 mm of filament
was
obtained. The filament was spooled to the winder as it extruded. ... The
processing
temperature was set at 180-200 C and 185 C via a twin screw extruder and a
filament
extruder, respectively. These temperature settings were only slightly higher
than the
melting temperature of the materials, which is a common practice in
determining the
processing temperature. Nevertheless, the printing temperature was set a bit
higher, at
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230 C. In fact, PA can be extruded down to as low as 190 C. However, the
thread
bonding of layered parts was not sufficient at temperatures below 230 C. From
DSC
and TGA results, PA displayed wide processing windows (temperature range from
melting to decomposition), therefore, a printing temperature at 230 C was
still
acceptable." Preparation and characterization of a newly developed polyamide
composite utilising an affordable 3D printer.
1004341 Thus, colorants (dyes, pigments) that can withstand these temperatures
can
be introduced to the process and extruded as photochromic filaments for 3D
printing.
1004351 (ii) Polymer clays ¨ see dyeing and coloring polymer clays e.g., in
Polymer clay coloring from glassattic.com, How to Color Polymer Clay The Very
Best Methods. Many experts recommend that water-based dyes should be avoided
in
polymer clays since the baking process would cause voids due to the water. One
process around that would be to roll out the polymer clay to a very thin
layer, and
provide sufficient heat to evaporate the water (but below the curing
temperature), and
then form the dyed polymer clay into the shape of the desired object and bake.
The
baking temperature of the polymer clay (275 F for Sculpey from Polyform
Products
Company (Elk Grove Village, IL)) must be considered in order to avoid the
temperature at which the dye breaks down and no longer functions as intended.
1004361 =Note that "Prussian blue does not begin to decompose thermally until
the
temperature exceeds 200 C." Cyanomicon - History, Science and Art of Cyanotype
-
Photographic Printing in Prussian Blue, citing Characterization of Prussian
blue and
its thermal decomposition products. Note that 200 C is 392 F. Many other
brands of
polymer clay are available from the Polymer Clay Superstore (Wemersville, PA).
Irreversible Photochromic pigment from New Color Chemical Co. Limited (Xiamen,
China) has a maximum specified temperature of 220 C.
1004371 (b) Metals - As an example, anodized aluminum can be dyed ¨ "During
the
type II anodizing process a porous anodic coating is formed when the aluminum
part
is processed in a sulfuric bath. The newly formed pores create a space for the
dye to
be absorbed into the surface of the aluminum. The anodized coloration process
works
through direct pigment injection into the empty pores of the part. Once the
colored
pigment reaches the surface, it's sealed off to preserve the selected color."
Arrow
Cryogenics Inc. (Blaine, Minnesota). UVC encapsulants can be considered for
sealing
as well.
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1004381 (c) Ceramics - "The use of cyanotype on ceramic substrates evokes
reminiscences of the attractive and celebrated blue Delftware. Regrettably
this
procedure is limited by the fact that if Prussian blue is fired under a glaze
it will
decompose thermally around 200 C, with the evolution of poisonous cyanogen and
hydrogen cyanide gases, destroying the blue and leaving only weak brown 'iron
earth'
coloured images (iron oxides). However, the sensitizer is easily imbibed into
a bisque-
fired ceramic surface, such as possessed by unglazed tile bodies. This is
still very
absorbent and needs its porosity to be restricted with a sizing agent, such as
gelatin."
Cyanomicon. Note that this comprehensive text on cyanotype also describes
other
formulations. The author, Mike Ware, would surely be considered a subject
matter
expert in the chemistry and photochemistry of cyanotype and related.
1004391 (d) Natural fibers ¨
1004401 (i) Wood flour ¨ is graded in size by 'mesh', which correlates to the
diameters as shown in the table, below (e.g., 200 mesh is a particle 75
microns in
diameter). Wood flour is sold in "20-100 mesh, with 100-200 mesh sieve's
available"
from Lignetics Brands (Louisville, CO) and in 100 & 200 mesh from PJ Murphy -
Forest Products Corp (Montville , NJ) See Table 15.1 of Functional Fillers for
Plastics, Ch. 15 Wood Flour, ISBN: 978-3-527- 32361-6 for the "Conversion
between
US standard mesh and particle diameter".
1004411 Other natural fibers include cotton and wood-based Cellulose
Nanofibrils
(CNF) that are tens of nanometers in width and under 3 microns in length and
Cellulose NanoCrystals (CNC) that are tens of nanometers in width and under
300
nanometers in length from Cellulose Lab (Fredericton, New Brunswick, Canada).
1004421 (e) 3D printable materials - While there may be overlap with the
previous
categories, only certain materials can be 3D printed, and thus it makes sense
to give a
summary of some of these. See, e.g., Polymers for 3D Printing and Customized
Additive Manufacturing, for a detailed summary of the deposition techniques
and
materials used. See also 3D Printing Temperatures & Printing Guidelines
Filaments.ca for a long list of 3D printable filament extrusion temperatures.
1004431 Wood ¨ "Just like real wood, objects 3D printed with wood filament are
porous, meaning they easily absorb different dyes and stains. ... If you have
access to
a CNC laser machine, an engraver, or even a pyrography set, you can add
features or
drawings to your finished piece of work." Wood 3D Printing Guide How to 3D
Print
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Wood A113DP. See also The Complete Wood 3D Printing Filament Guide
3DSourced. Current technology uses a PLA (polylactic acid) filament, with 20%
to
40% wood content. See, e.g., 3D Printing Matefials - Feels, Smells Like Wood.
The
earlier referenced list shows Laywoo-D3 (Orbi-Tech GmbH, Leichlingen, Germany)
is specified from 165 C - 250 C, with 165 C - 180 C for bright/light color
wood
effect. MatterHackers Inc. (Lake Forest, CA) recommends "190 C to 250 C.
Printing
at lower temperatures will produce a brighter color while printing at higher
temperatures will create a darker print", see Light Cherry Wood Flexible
LAYWOO-
D3 Filament - 1.75mm10.25kg).._Mattedbc_kers In Laywoo-D3 review (Jan
Hisocks), it states "This printed nicely between 190 C and 255 C with varying
colour
as the temperature increases, if you print up to approximately 225 C the
colour will be
a lighter tone than 225 C to 255 C ..."
1004441 Recall stock cyanotype dye is limited to 200 C and New Color's pigment
at 220 C, and thus these photochromic materials can be incorporated within the
base
filament such that avatars can be printed without requiring a postprinting
coating step.
See also Effect of Extrusion Temperature on the Phvsico-Mechanical Properties
of
1.Jnidirectional Wood Fiber-Reinforced Polylactic Acid Composite (WFRPC)
Components Using Fused Deposition Modeling. In Fabrication of PLA Filaments
and
its Printable Performance, filaments were manufactured via extrusion from raw
PLA
particles at temperatures as low as 190 C. Natural fiber composite PLA
manufacturing is discussed in Natural fibre reinforced polylactic acid
composites - A
review. These natural fibers include wood and other fibrous materials that are
known
to accept cyanotype dye. A manufacturing process for a PLA/wood composite is
disclosed in Effect of wood content in FDM filament on properties of 3D
printed
parts. "Regarding filler content, the objective was to maximize biomass
content while
ensuring that the printer does not have many flow problems when printing
hundreds
of samples. This value for ball-milled poplar turned out to be 20 wt.%. 210 C
was the
most suitable filament extrusion temperature for 20% ball-milled poplar and
80%
PLA after testing in the range of 190-230 C. ... Extruder temperature of 190
C and
extrusion at the highest speed at 15% fibrillated poplar content were found to
be the
best conditions for the fibrillated poplar containing filaments, which were
then used
for printing and characterization. ... Based on the tensile stress¨strain
curves, it was
decided that ball milling was the preferred choice for size reduction over
friction
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grinding (fibrillation)." Tensile properties of 3D-printed wood-filled PLA
materials
using poplar trees. Hence, fibrillated poplar fibers provide lower processing
temperatures necessary for certain photochromic materials, wherein the use,
e.g., in
3D printing avatars for dosimetry, are not subjugated to high tensile loads.
1004451 Foam - "LW-PLA is the first filament of its kind using an active
foaming
technology to achieve lightweight, low density PLA parts. At around 230C this
material will start foaming, increasing its volume by nearly 3 times."
colorFabb BV
(Belfeld, The Netherlands) Foam has a very high surface area, enabling dyes
more
contact area for bonding. Foam also provides a texture akin to bread and other
bakery
products.
[00446j (f) Paper dosimeters used in novel ways ¨ First note some published
uses
of such dosimeters. In Ultraviolet-C decontamination of a hospital room -
Amount of
UV light needed, co-authored by paper-dosimetry manufacturer Intellego
Technologies AB (Sweden), is states in part: "Indicators (surfaces) in the
direct line of
sight and vertical to the UVC device showed a more distinct change of colour,
thus
indicating that the UVC dose received was higher than that received by
indicators
(surfaces) placed horizontally, or shadowed by equipment or furniture, or both
(Fig
2A)." More recently, in UV dosimeter Badges - An Emerging Tool for Monitoring
Delivered Dose (UV Solutions magazine, Ql, 2021), paper dosimeters ('UVC 100
Dosimeters by Intellego Technologies' and `UV Intensity Labels by UV Process
Supply') were affixed to various 'complicated' objects ¨ "Four objects were
selected
to evaluate the usefulness of the dosimeter badges as an identifier for LTV
dose on
varying complicated geometries in a typical commercial UV-based disinfection
device
(i.e., the LuminTM) The four objects were a razor, comb, sunglasses and keys.
... Six
dosimeter badges were attached to each object individually. Each badge
placement
was documented by photographing the object in two positions, one displaying
the side
of the object that would face the lamp and the other showing the opposite. The
lamp-
facing side of the object was named Side-1, and the bottom-facing side was
named
Side-2. ... dosimeter badges can be used to generally assess where UV light
has
touched a surface. This can help researchers in identifying areas that are
shadowed
from light and have not received any dose at all."
[004471 In an exemplary embodiment, the dosimetric avatar integrates paper
dosimeters. For example, a 3D printed strawberry (although it can be
fabricated by
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any process, such as those cited herein) is made with slots and hinged surface
portions
for acceptance of an optionally textured paper dosimeter (or portion of one
depending
upon the size of the avatar). In one embodiment, the paper is used to capture
the UVC
received by the general surface profile of the strawberry. In another
embodiment,
apertures are formed in the 3D printed part such that the paper dosimeter is
located
behind the apertures and is shadowed by the walls forming the apertures
(mimicking,
e.g., the achenes of a strawberry). Thus, the shadowing features can come from
a
textured paper/cardboard dosimeter, features in a (3D printed) carrier
(microscopic
and/or macroscopic shadowing surfaces including shadowing due to the overall
convexity of the avatar), or both. In one embodiment, commercially available
paper/cardboard dosimeters are embossed (by a supplier or the customer) with a
pattern representative of the texturing of a target object. These may be cut
into small
shapes (using, e.g., optional dashed lines on the dosimeter) and then inserted
into a 3D
printed 'carrier' shaped like a strawberry. The carrier may also be a generic
one,
enough to provide some convexity like the Platonic solids (the five regular
polyhedra
- tetrahedron (or pyramid), cube, octahedron, dodecahedron, and icosahedron.).
A
more exact geometry can he developed by importing a 3D strawberry model (as
cited
herein), simulating the UVC irradiation system and its effects on the
strawberry via a
ray tracing program (e.g., such as TracePro from Lambda Research Corporation,
Littleton, MA), then constructing an avatar design with (near) equivalent
performance.
1004481 Design methodology of features in 3D printed parts suitable for
capturing
paper dosimeters include 3D printed hinges (see, e.g., How to design living
hinges for
3D
printing 3D Hubs), snap closures (see, e.g., How to design snap-fit joints for
3D
printing
3D Hubs), slots behind and parallel to the surface - see, e.g., 3D Print
captured nuts
without pausing your print, which are used to capture nut-fasteners, and for
the instant
invention, the slots can be adapted to capture dosimetric paper, including
optional
features to prevent the paper from sliding out, such as by pinning using a
fastener, or
making the slot gap not much bigger than the thickness of the paper, and
placing a lip
at the entrance to the slot to ensure the paper doesn't slide out.
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1004491 =Note that textured materials such as beads and fibers can be
deposited/affixed on paper dosimeters to provide shadowing, either with a
degree of
transmissibility or not. These textured papers can then be inserted in an
avatar. In fact,
3D printed strawberries can be printed on top of a scaffolding supporting
paper
dosimeters to create an integrated dosimetric avatar, so long as the printing
temperatures (and other effects) do not cause the paper dosimeter to degrade
to an
unusable state in the process.
1004501 Less accurate avatars may be constructed to gather first order
effects; for
example, a cylinder of about the diameter of a strawberry can be constructed,
a
dosimetric paper wrapped around it, and then a mesh surface wrapped around the
cylinder to emulate shadow-inducing textures. Faceted shapes (e.g., truncated
pyramids) lend themselves well to paper dosimeters. Any object can be
constructed
from a low-res mesh-model that can inherently provide such faceted shapes by
limiting the number of nodes. These shapes can take advantage of the adhesive
backing on paper dosimeters, which can be simply stuck to the facets. Once
irradiated
and the dosimetric patterns are captured (e.g., via photogrammetry), the
faceted
avatars can he bathed in a solution to aid in removal of the adhesive from the
paper
dosimeters so that the objects can be reused with new paper dosimeters.
1004511 (g) Paper forming techniques used to build avatars - The following all
provide additional background on design and fabrication techniques. As
mentioned
herein, weights can be added to provide a closer inertial copy of the actual
object.
1004521 (i) Origami techniques (see, e.g., Origami Strawberry) can be used to
construct avatars directly from paper dosimeters. Once irradiated, they can be
unfolded and simply scanned on a flatbed scanner. Each facet can be numbered
to
have geometric references when viewing the scanned image. The avatars would
always be folded in the same way, so the references always relate to the same
surface
feature on the avatar. The folding lines can also be printed on the dosimeter
paper.
1004531 (ii) Tissue paper honeycomb construction --- see, e.g., Large Tissue
Paper
fruit and vegetable decorations. This approach naturally forms a texture-like
depth
that generates shadows.
1004541 (iii) Other paper construction ¨ see the faceted construction, e.g.,
Paper
Fruit - Mr Printables, folded construction, e.g., HANDMADE' 3D fruits and
vegetables from payer (original work) ¨ Steemit.
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1004551 (iv) Cardboard construction - "The following techniques require no
glue to
attach cardboard together: Interlocking Slots Interlocking slots are thin
slots cut into
Iwo pieces of cardboard that intersect each other at an angle to allow the two
pieces to
hold themselves together. The slots must be cut slightly thinner than the
thickness of
the cardboard so the friction of the mating piece in the slot will help hold
the pieces
together. Tab-n-Slot A tab-n-slot is a tapered tab that has slots cut on
either side of it.
The slots allow the end of the tab to be folded in on itself from both sides.
The tab is
then inserted into a slot cut into the mating part. The slot must be just wide
enough for
the folded tab to squeeze through, but narrow enough that when the ends of the
tab are
folded back out they retain the tab locking it into the mating part."
Cardboard 101.
Note that folding can be used without tab-n-slot as well, either with another
method to
stabilize the shape (magnets, adhesives, hook-and-loop, etc.) or without any
such
mechanisms if the material is stiff enough to hold its shape (e.g., cardboard
laminated
to metalõ or even hand-bendable metal sheet instead of cardboard). These
constructions can use textured sheet material surfaces or not, depending on
the
application. 3D printed sheets with integral hinges can be deployed as well,
with or
without texturing.
1004561 This type of construction is interesting in that after irradiation,
the pieces
can be pulled apart (or splayed back to planar-form, and optionally held flat
by a
fixture) and then placed on a flatbed scanner (or equivalent) for extracting
information
to feed into a dosimetric analysis. As mentioned herein, metal interlocking
plates each
can be overlayed with adhesive-backed paper dosimeters to provide an avatar
with
inertia more similar to the real object. One can also construct pieces using a
jigsaw-
puzzle type arrangement, either a traditional 2D arrangement, or a 3D jigsaw
puzzle
as can be found on website of the Puzzle Warehouse (St. Louis, Missouri). See
also
GB2499381A 3D puzzle formed using CAD and CAM processes.
1004571 (v) Molded wood/paper pulp ¨ see, e.g., US10377547 Methods and
apparatus for in-line die cutting of vacuum formed molded pulp containers,
also citing
the use of dyes and coatings. Molded pulp is well known for its use in egg
cartons
(US4088259 Die-dried molded pulp egg carton) and cup carriers (US7762396 Cup
carrier).
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1004581 (7) Surface texturing - A recent publication on the issue of surface
textures
in UVC disinfection systems is Surface Textures and Implications for Needed
Standards.
1004591 As cited herein, a strawberry surface texture is on the order of 1000
(1mm) in feature size (relief). This creates a `micro-shadow', unlike the
shadows
created by the general curvature of the strawberry's gross convex geometric
shape. A
micro-shadow does not need to be tiny ¨ it results from a finer undulation
within the
gross shape of an object. Another example would be an N95 mask that has a
general
curvature that will create shadows, but it also has a fibrous texture that
creates micro-
shadows.
1004601 One method, especially suited to paper/cardboard dosimeters (but
applicable to any material that can be deformed), is to use embossing to
create a
textured surface. See, e.g., 4 Ways to Emboss Like a Boss The Paper Blog
("Debossing is basically the opposite of embossing. Instead of creating a
raised
pattern, debossing creates an indented pattern.") The Graphic Designer's Guide
to
Embossing ¨ ZevenDesign (states in part, "Although embossing seems to be quite
deep visually, it is commonly no more than 15 microns and at most, 25
microns."),
Performance evaluation of oaer embossing tools Droduced by fused de osition
modelling additive manufacturing technology ("Results show that paper
characteristics determine the embossing force required for achieving a good
embossing result ... with the right amount of embossing force, letters and
borderlines
can be equally well formed by the embossing process regardless of paper
weight,
surface characteristics, etc."). "... the "blind emboss," which involves only
the raising
or lowering of the image on the paper (and not printing or foiling anything).
This
creates a subtle, sophisticated effect. You may have seen the results of blind
embossing on a notarized document or even a "This book is the property of..."
stamp
inside a print book you have borrowed. (You can get such personal embossing
stamps
online for your own library with your own name on the die. If you look
closely, you
will see the two interlocking elements of the die.)" Embossing Printing
Industry
Blog.
[00461] High relief blind embossing is available, e.g., from Eisenhardt
Printing
Company (Frankfurt, Germany), cited in Design Inspiring_ Distinct Blind
Embossed
Business Cards where the "emboss itself is 3mm high on Gmund Cotton Linen
Cream
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222 lb Cover." High relief is also discussed in US20070062658 Absorbent paper
product having high definition embossments at [0061]: "The embossed paper
product
of the present invention comprises one or more plies of paper. At least one of
the plies
is embossed so it comprises a plurality of embossments. In one embodiment, the
embossments of the product of the present invention have an embossment height,
h, of
greater than about 800 microns. In another embodiment, the embossments have an
embossment height of from about 800 microns to about 2500 microns. In other
embodiments, the embossments have an embossment height of from about 1000
microns to about 2000 microns. In other embodiments still, the embossments
have an
embossment height of from about 1250 microns to about 1750 microns. The
embossment height, h, is measured using the Embossment Structure Measurement
Method described in the test methods section herein. Referring to FIG. 5, the
embossment height, h, is a measure from the top of the unembossed structure to
the
bottom of the embossment as described in the test methods section. In an
embodiment, the embossments have an emboss impression angle of less than about
150 degrees. In another embodiment, the embossments have an emboss impression
angle of from about 90 degrees to about 150 degrees."
[00462] Paper product dosimeters can be embossed either before or after the
paper
is treated with the photochromic chemical(s). An advantage of embossing before
treatment is that the paper can be embossed as far back in the process as when
it exists
in a slurry form, allowing greater relief depths without tearing.
[00463] A list of embossing machines can be found in Top 13 Best Embossing
Machine on The Market with Reviews 2021.
[00464] Multi-level or sculptured embossing can create more sophisticated
profiles
(like a more realistic strawberry texture, given the surface profile cited
herein), see,
e.g., Multi-Level Embossing Kicks It Up a Notch, Reaches New Depths
PostPress.
Multi-level and sculptured embossing dies in brass are available, e.g., from
E.C.
Schultz & Company (Elk Grove Village, IL). In a preferred embodiment, a paper
dosimeter like UVC 100 dots would be embossed using a custom sculpted
embossing
die suitable for a handheld or tabletop embossing tool, such as those used by
notary
publics, e.g., from Indiana Stamp (Fort Wayne, IN).
[00465] As a simple test, the corporate seal from Luminated Glazings was
embossed onto standard 20 lb. Hammermill copy paper (International Paper
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Company, Memphis, TN), measuring .003" thick. After embossing with the
corporate
seal, the thickness of the seal area measured .015". Similar embossing is used
for
notary publics. A simple test platform would be to purchase a notary public
seal or a
custom embosser, e.g., from Ideal Impressions, Inc. (Monsey, NY) dba Ideal
Stamp
Shop.
1004661 A UVC Dosimeter Card, SKU 201188 (two-colors, 50 mJ/cm2 to 100
mJ/cm2) was purchased from CureUV (Delray Beach, FL). The stock paper measured
.019" thick (about 6 times thicker than the 20 lb. copy paper). The Luminated
Glazings corporate seal was embossed onto a portion of the card, and the
maximum
thickness after embossing was .034", or .015" thicker than the stock paper.
The label
was marked `www.americanultraviolet.com' on the back, and the same two-color
card
can be seen on the American Ultraviolet website as SKU UVC-TAB-F-25-1. A
similar card is the UVC100-DUO from Intellego Technologies (Stockholm,
Sweden),
and note that American Ultraviolet is a 'partner' of Intellego Technologies as
per the
Intellego website.
1004671 In order to understand whether an embossing can create the depth of
profile of a real strawberry, an epoxy cast of a portion of the surface of a
large
strawberry was made, and the dimensions of the surface texture was measured to
rough order (3D models are available as previously cited, from which a high
fidelity
surface texture dimensions can be captured). The oblong shaped achenes are
roughly
7/64"apart within each row, with adjacent rows about 5/64" apart. The achenes
are
roughly 1.5/64" wide x 7/64" long x 1/64" deep, and each sit in a well that is
about
3/64" wide x 4/64" long x 2/64" deep. So, the depth of this texture, to rough
order is
about 2/64" = .0312" = 0.79mm. Thus, the texture of this particular strawberry
was
about twice as deep as the depth of an embossed piece of 201b copy paper.
However, a
smaller strawberry would have a similar texture but on a smaller scale. An in
terms of
shadowing, the dimensionless aspect ratio (e.g., width/depth or length/depth)
effectively defines the 'canyon wall effect' (see, e.g., UV-C Effectiveness
and the
'Canyon Wall Effect' of Textured Healthcare Environment Surfaces UV
Solutions,
although 'aspect ratio', per se, is not cited). Of course, the 'wall'
structure of the
canyon (slope angle(s), any texturing on it, reflectance, etc.) will also
affect the
shadowing, but to first order, replicating the gross features of the 'canyon'
can be
very-helpful. Now, the aspect ratio of the measured strawberry is roughly
(3/64") /
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(2/64") or 3/2 in width/depth or (4/64") / (2/64") or 2/1 in length/depth. If
the
maximum depth of embossing a dosimeter paper is the same as 201b copy paper,
the
depth is .015", and therefore the feature width could be set to (x/.015" ¨
3/2, so
x=.022") and the feature length set to (y/.015" = 2/1, so y=.030"). This can
be used
for an embossing depression having an ellipsoidal cross section, or these can
be
averaged (.026") for a circular cross section. Specific sidewall slopes can be
added,
but for a first order effect, the standard low cost, single-level embossing
die
fabrication method can be used (e.g., via etching) yielding its characteristic
sidewall
slope.
1004681 In an exemplary embodiment, a .019" thick UVC Dosimeter card from
CureUV (SKU 201188, or the equivalent from American Ultraviolet, Lebanon, IN)
is
purchased, and then embossed with a texture similar to that of a strawberry,
with
maximum depth of texture .015", representing the depth to the bottom of the
achenes
of a certain sized strawberry. Based on the previous analysis, the aspect
ratio
W/D=3/2, and L/D=2/1, and so each embossed achene feature starts as an oval
shape
(3/2)(015")= .022" wide by (2/1)(.015")=.030" long, with a depth of .015"
below the
indicating surface of the stock Dosimetric card These cards (or the just the
central
photochromic section) can be placed on the sides of a faceted strawberry
dosimetric
avatar.
1004691 (8) UVC surface reflectance - One aspect in producing dosimetric
avatars
of a given fidelity is to understand the significance of the UVC surface
reflectance of
the targeted objects (e.g., strawberries). A reference to the issue of UVC
absorbance
of fruits, in addition to shadowing/shielding is cited here: "In inoculated
fresh fruits, a
greater UV shielding efficiency was observed, because microorganisms may
reside in
crevices or in irregularities (injuries) present on the fruit surface or may
penetrate
under the fruit's epidermis. This shadowing effect of coherent PUV photon
sources
used in these experiments is illustrated in Figure 2. Therefore, a larger UV
exposure is
required, because many chemical components in plant tissues are capable of
absorbing the UV energy, thus becoming effective chemical absorbers of UV
light."
Development of Pulsed UV Light Processes for Surface Fungal Disinfection of
Fresh
Fruits. Note that this reference promotes rotation of fruits for better UVC
coverage.
1004701 In order to better quantify the significance of UVC reflectance of
fruits
(low reflectances require a direct hit on the pathogen with the UVC, as the
portion
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reflected from an adjacent surface would be of very low intensity). Published
data for
UVC reflectance of some fruits are disclosed below.
1004711 The UVC reflectance of blueberries are shown in Figures 2 & 3 of
Classification of blueberry fruit and leaves based on spectral signatures. The
y-axis in
the plots below is specified as 'Absorbance (log(1/12)'. Rearranging, R=10-A,
where R
is % reflectance and A is absorbance. As shown in the plots, in the UVC range,
both
leaves and fruit have absorbance values between about 0.8 and 0.85, thus
reflectance
values of 10(M8)=158% and 10085)=14.1%. Note the differences as the fruit
matures
and between varieties. This provides a template for testing other
fruits/vegetables/etc.
1004721 It should be noted that Thyperspectral' data has been collected by
various
groups for many fruits, serving as an indicator of fruit quality, ripeness,
etc. However,
very-little is collected in the UVC range (mostly Vis/N IR); see e.g., Table 1
of
Extraction of Spectral Information from Hyperspectral Data and Application of
Hyperspectral Imaging for Food and Agricultural Products, Table I of Optical
non-
destructive techniques for small berry fruits - A review.
[00473] When making a dosi metric avatar of a fruit, the UVC reflectance
(254nm)
of nonfruit should ideally match that of the actual fruit The INC reflectance
of some
common materials are available in UV Disinfection - Application Information
(Philips
brochure) .It includes a wealth of other data (including papers) useful in
constructing
UVC reactors. As an aside, the UVC reflectance of paper dosimeters is not
specified
by the manufacturers (although it can be measured).
1004741 Published information of UVC reflectivity down to 250nm of exemplary
3D printable materials (colored and colorless PLA) are shown in The Optical
and
Thermal Properties of PLA Filament in a Context of Material Colour and 3D
Printing
Temperature. See also Characterization of the Reflectivity of Various Black
Materials
H.
1004751 (9) UVC degradation of 3D printable materials as a dosimeter ¨
1004761 Photodegradation-induced property changes such as weight and
coloration
can be used for dosimetry as discussed for PLA in The Effect of UV Treatment
on the
Degradation of Compostable Polylactic Acid. Changes to water contact angle and
mechanical strength for PLA under UV exposure is discussed in Mechanical
Properties of 3D Printed Polvlactic Acid Parts under Different Testing
Conditions.
Note that much of the available data is for UV wavelengths other than UVC, but
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correlations are reasonably expected. The time constants of PLA filament aging
must
be understood if used as an avatar. See Effects of Ultraviolet Aging on
Properties of
Wood Flour-Poly (Lactic Acid) 3D Printing Filaments. Other polymeric mateiials
are
disclosed in Effect of UVC Exposure on Non-Metallic Materials in HVAC Systems.
1004771 (10) Weight and inertia of avatars - For fidelity to an actual object,
the
weight and inertia should be the same in order to mimic, e.g., the natural
tumbling/movements of an object carried by a conveyor belt through a UVC
tunnel,
which can also be impacted by the friction between the object and the tunnel
belt.
1004781 One analogous technique is to add specially shaped weighted blocks
within an object to change its inertia, such as that done with the
manufacturing of
bowling balls - see e.g., The insides of pro bowling balls will make your head
spin
Popular Science, A Look at the USBC's Bowling Technology Study, and What makes
bowling balls hook, also citing the effects of friction on rolling.
1004791 Other analogous techniques can be seen in the weights added to tires
for
balancing, and selective removal of material room high speed shaft assemblies
for
balancing Of course, weight changes can be used to induce imbalance
conditions.
1004801 In the case of 3D printed (or machined) parts, one or more inner
cavities
can be defined for acceptance of a material of different density (or it can
remain
empty) to better emulate, e.g., the natural tumbling of a strawberry along a
conveyor
belt. In the case of paper/cardboard parts, weights can be added to a central
core, or a
frame can be made from metal, with paper dosimeters adhesively attached.
1004811 Surface textures (including surface hardness & firmness) can affect
the
friction/dynamics between a dosimetric avatar and, e.g., the transport belt in
a UVC
tunnel, and therefore impact whether sliding/tumbling of an avatar is similar
to a real
object. Thus, for high fidelity dosimetry, surface textures should be
considered.
[004821 (11) Adhesion of photochromic materials
1004831 Dye additives - see, e.g., US6942705 Method of dyeing thermoplastic
resin article and colored plastic lens obtainable by that method, claiming the
use of a
monocyclic monoterpene with the dye.
1004841 Primers - See, e.g., products such as Leather World Plastic Primer -
"Excellent water-based plastic primer for most automotive plastics and hard
vinyl
panels. This makes an excellent base for Dye Colorant to adhere to the hard
plastic or
vinyl trim." Leather World Technologies (Roanoke, VA). See also Water Base
Plastic
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Primer - "used when dying plastic with water base colors" from Superior
Restoration,
Inc. (Sacramento, CA).
1004851 Watercolor Grounds ¨ a brush-on porous surface coating suitable for
application on plastics and other surface materials. Traditionally used for
covering-
over mistakes in watercolor paintings, allowing the surface to be repainted
with
watercolors. Manufactured, e.g., by art supply company Daniel Smith (Seattle,
WA).
Similar 'primers' for dyes are discussed in How to Use Anti Spread Techniques
and
Products - How to (Wild) - Silk Painters International.
1004861 (12) Adhesives and coatings
1004871 Fine sprays - see, e.g., 3M Spray Adhesives Brochure. See material
compatibility chart for use on plastics, metals, etc. See also adhesives with
"mist"
spray patterns. See also 6000 Spray Adhesive (Eclectic Products, Inc.,
Eugene, OR),
Glue for Glitter (DESIGN MASTER color tool, inc., Boulder, CO). Note that in
one
experiment, 6000 spray adhesive was sprayed on a fake plastic strawberry,
then
brushed smooth with an acid/flux brush to maintain the surface profile of the
strawberry. Glow phosphor was then sprinkled on, followed by tapping the
coated
strawberry to shake off loose particles The technique worked well Note that
the
coated strawberries could then be placed in an air pressure chamber to further
aid in
embedding the particles into the adhesive to the degree desired. A UVC
encapsulant
could then be used to provide a food-safe seal around the particles while
still
providing UVC and visible light transmissibility to/from the particles. The
E6000
Safety Data Sheet states it is made from Styrene, 1,3- butadiene polymer and
tetrachloroethylene. UV absorbance is given for styrene-butadiene in Analysis
of the
Absorption Spectra of Styrene-butadiene in Toluene.
[00488] Brush/Vapor ¨ In an analogous art, cyanoacrylate (instant) adhesives
are
used to adhere powders in the manicure industry, see, e.g., All About Dip
Nails!.
Note that the cited use of any overcoats may not be suitable if it should
block UVC
from reaching photochromic powders, and thus the simple cyanoacrylate adhesive
base layer may be sufficient in such applications, although a UVC transparent
encapsulant (such as one or more of those cited herein) can be used as an
overcoat
(and food safe as applicable). Also note that cyanoacrylate adhesives easily
vaporize,
providing another high resolution application method. In another analogous
art, such
vapors are used to detect fingerprints, see, e.g., The Cvanoacrvlate Filming
Method
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and Superglue Fuming For The Chemical Enhancement Of Latent Fingerprints, for
the processes used to vaporize the adhesive and condense onto object avatars
(e.g., a
fake strawberry), after which photochromic powders can be applied (and
encapsulants, if desired, as cited previously).
1004891 UVC transmitting adhesives, coatings, and encapsulants for paper-based
avatars to work in the fog field, they must receive UVC light and cannot
degrade due
to the high RH during operation (true for any other materials for use with the
instant
invention, such as UVC LEDs). One method of protection is to laminate a
protective
window using a LTVC transmitting adhesive/tape. Another method is to
encapsulate or
conformally coat the sensitive device.
1004901 (i) Tapes ¨ see, e.g., 3M P/N 0CA8146-2 and 0CA8146-3, available from
Thorlabs (Oak Ridge, NJ). See Thorlabs.com - Optically Clear Double-Sided
Adhesive Tape. Best suited for planar surfaces.
1004911 (ii) Coatings/encapsulants/adhesives ¨ see, for example 1. SCHOTT
(Duryea, PA) Deep UV-200 Silicone Adhesive as cited in Heterostructure design
and
epitaxial growth of AlGaN-based light emitting diodes emitting in the UVC
wavelength range; 2 Dow (Midland, MT) Silasti CTM Moldable Optical Silicone; 3
Dupont (Wilmington, DE) Fortasun 6212, see DuPont Fortasun_Launch_Tech
Sheets_PV-6212 Cell Encapsulant 4. KF-96-50CS dimethylpolysiloxane silicone
oil
(Shin-Etsu Chemical Co., Ltd, Tokyo, Japan) as cited in A Novel Liquid
Packaging
Structure of Deep-Ultraviolet Light-Emitting Diodes to Enhance the Light-
Extraction
Efficiency; 5. Master Bond Inc. (Hackensack, NJ) UV LED Encapsulant, see e.g.,
Optical Transmission Properties of Adhesives MasterBond.com, with their
MasterSil 151 (a 'two component, low viscosity silicone compound for high
performance potting and encapsulation' that 'cures at room or elevated
temperatures')
and MB600 (a `low viscosity' 'sodium silicate adhesive/coating' with a 'widely
used
cure schedule is 45 minutes at 200 F followed by another 60 minutes at 300-400
F')
products well suited for UVC (and visible) light applications.
1004921 Other means by which photochromic materials can be attached - Many
other processes are contemplated for attachment of photochromic materials such
as
vacuum coating, electrostatic powder coating, etc., given that they are
compatible
with the temperatures and other aspects of the respective coating process(es).
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1004931 Calibration images/targets - In order to accurately discern a dosage
on a
dosimeter, calibration colors have been used historically for comparison
purposes.
This can be seen, e.g., on the commercially available UVC 100 Dosimeter Cards
from
Intellego Technologies (Stockholm, Sweden), that "feature a yellow indicator,
surrounded by two reference colors (orange and pink) to indicate UVGI doses of
50
and 100 mJ/cm2." In a similar fashion, dosimetric avatars can be used with
calibration
features, either on the avatar itself, on a card near where the avatar will be
sensed after
exposure, or relative to a computerized data file that was derived from the
same
photochromic material, which is exposed in a quality control lab, e.g., on a
daily
basis, along with one or more dosimetric avatars to ensure proper dosimetric
sensing.
Note that ambient light conditions must be considered when correlating an in-
line
dosimetric avatar to the calibration target. For example, a visible light
calibration card
(to sense ambient light) would be placed near the camera(s) used to measure
the
dosimetric avatar. Open source software for camera calibration is referenced
in
Camera Calibration Toolbox for Matlab from the California Institute of
Technology
(Pasadena, CA). A comprehensive discussion of issues encountered in
correlating
image capture to calibration images for fruit (bananas) Assessment of banana
fruit
maturity by image processing technique. This paper was cited in later paper
looking at
both bananas and strawberries, Monitoring the Change Process of Banana
Freshness
by GoogLeNet. The paper also discloses a recently developed technique called
'transfer learning': "Transfer learning is a new machine learning method that
uses
existing knowledge to solve different but related problems ... A total of 104
strawberries were collected, and 312 photos of strawberries were taken as a
data set.
After the same operation steps and 2100 iterations, the recognition accuracy
of the
model is 92.47%. The accuracy and loss curves in training are shown in Figure
11.
The strawberry change is more challenging to recognize than the banana because
the
strawberry itself is red. When it goes bad, the color changes to a deep red,
so the back
and forth changes are less obvious. However, our model can still achieve high
accuracy. The results show that the model has good adaptability and can be
used for
various fruit identification." For the instant invention, instead of real
strawberries,
they could be dosimetric avatars, and in fact, transfer learning (e.g., via
the intern&
through a secure network to the cloud administered by the Assignee and/or its
delegates) allows access, e.g., to updated dosimetric avatar data for
different types of
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objects. This also enables a business model comprising maintenance fees for
access to
the trade secrets hosted in such a transfer learning database. Of course, this
business
method can be extended to any business, especially those that use machine
vision,
from fixed camera embedded systems to portable cameras like a GoPro (San
Mateo,
CA) or those on iOS and Android smartphones. Note that the transfer learning
database can also hold additional data related to objects, and so for the
example of a
UVC tunnel, such data includes one or more of: model number of the UVC
irradiation
system and its operating parameters like beltspeed/temperature/humidity/dry-
fog data,
camera calibration data (including ambient lighting radiometry), UVC
radiometry for
correlation to the type of UVC lamps being used (LP/MP/Xenon/LED), date codes
of
equipment and avatars, dosage levels necessary for a given object (be it for
UVC to
kill certain pathogens or VIS/N1R to accelerate the growth of certain
greenhouse
fruit/vegetable varieties), etc.
1004941 Photogrammetry for measuring visual changes of irradiated objects -
Qlone (Yokneam, Israel) is an Android/i0S smartphone app that can generate a
3D
model of an object (include surface colors) by placing the object atop of a
paper
calibration grid and guiding the user to move the smartphone's camera in
azimuth and
elevation (as directed by the app's hemispherical grid). The app exports (for
a fee)
objects in 3D formats such as OBJ, STL, USDZ, GLB, FBX, PLY and X3D. A
discussion of the data within 3D file formats can be found in An Overview of
3D Data
Content, File Formats and Viewers. Using this information, one can extract (or
pay
for an expert service to extract) the color/intensity information from the 3D
rendering
on the irradiated object automatically and provide data (including statistics)
that can
be interpreted to characterize the quality of the irradiation, quantitatively
and/or
qualitatively, where the former, e.g., can determine whether the irradiation
is
inadequate, and the latter, e.g., can provide a sense of how the irradiation
varies over
the object. A simple az/el fixture for use with apps like Qlone can be found
in For
Better Photogrammetry. Just Add A Donut Hackaday and automated configurations
are described in Automating Photogrammetry with Foldio360 Smart Turntable
(Update 2018). Other applications and hardware platforms can be found in,
e.g.,
Photogrammetry: Step-by-Step Guide and Software Comparison. Consultants can
assist in developing a photogrammetry solution, e.g., Nick Lievendag
(Amsterdam,
North Holland, Netherlands) is a consultant in the area of photogrammetry, and
his
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ylog 3Dscanexpert.com provides reviews of hardware and software, including
professional grade equipment such as those from 3D scanning manufacturer Artec
Europe (Rue des Peupliers, Luxembourg).
1004951 See also A new, open standard for 3D imaging data for other point
cloud
scanning technologies (LlDAR, etc.) and file formats. The holding structure
(and
other features not associated with the desired object) can be automatically
eliminated
in photogrammetry by constructing it in a manner much like a 'green screen' is
eliminated in video production. Features of the holding structure include
color,
pattern, transparency, thinness, temporal changes, temperature, absolute
coordinates,
special coating that causes the holding structure to change its (optical)
characteristics
without causing a change in the object's characteristics, etc. See, e.g.,
Using Prior
Knowledge for Verification and Elimination of Stationary and Variable Objects
in
Real-time Images, A background subtraction algorithm for detecting and
tracking
vehicles. "Subtraction, masks ... A binary image is called a mask. It may be
used to
cut specific content off other images ..." Digital Photogrammetry - A
Practical
Course (ISBN 978-3-662-50462-8).
1004961 "The image of the strawberry was obtained by a 3D
laser scanner (Next
Engine, USA). The equipment consisted of a calibrated camera, a rotation
table, a
laser source and a computer with ScanStudio HD software (Next Engine, USA).
Scanning, aligning, trimming, filling holes and fusing are the main processing
features
used to produce a single surface mesh. The image acquisition process and the
strawberry surface obtained are shown in Fig. 3a and 3b. The distance from the
lamp
surface to the base of the strawberry was 150 mm. Three geometries were
created
with the strawberry calyx on its side, top, and bottom (Fig. 4a)." Simulation
of UV-C
Intensity Distribution and Inactivation of Mold Spores on Strawberries
1004971 Close-up and macro photography - Discerning the photochromic
differences of an exposed dosimetric avatar from an object with a textured
surface can
be challenging. Close-up or 'macro' photography is used for imaging at very
close
distances. See, e.g., Close Up And Macro Food Photography Ideas You Should
Try,
and How To Take Great Macro Photos With Your iPhone. Note the add-on lenses
that
can be attached to smartphones. Also note the trend of more sophisticated
camera/imaging technologies in smartphones. See, e.g., Recent trends in
smartphone-
based detection for biomedical applications - a review, citing such uses as
Routine
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diagnosis, Bacterial detection, Virus detection, Food quality control, Deep
learning
for smartphone-based imaging devices (SIDs) It is anticipated that this trend
will
continue, aiding the functionality/productivity of the instant invention. See
also New
Imaging Options for Conservators. Restorers. Curators. Forensics. Document and
Material Examiners Linkedin, describing "Z-stacking", where "in-focus images
from different levels are electronically combined into a single 'all-in-focus'
image." Z-
stacking (aka focus stacking, focal plane merging, and focus blending) is
described
further in Focus stacking ¨ Wikipedia, "... a digital image processing
technique which
combines multiple images taken at different focus distances to give a
resulting image
with a greater depth of field (DOF) than any of the individual source images.
Focus
stacking can be used in any situation where individual images have a very
shallow
depth of field; macro photography and optical microscopy are two typical
examples
..." 3D models can be constructed from such images, see, e.g., An automated
device
for the digitization and 3D modelling of insects. combining extended-depth-of-
field
and all-side multi-view imagine. See also US9224193 Focus stacking image
processing apparatus. imaging system, and image processing system, US8287195
Motor controlled macro rail for close-tip focus-stacking photography Focus
stacking
software for macro photography is available, e.g., from Zerene Systems LLC
(Richland, WA). Exemplary high quality close up images can be seen from the
works
of Rob Kesseler, e.g., a co-author in Fruit: Edible, Inedible. Incredible
(ISBN 978-
1608872817). Extensive teachings in the art of close-up and macro photography
can
be found, e.g., in Close-up and macro photography: its art and fieldcraft
techniques
(ISBN 978-1315620800). These techniques can be combined with
photogrammetry/automation as cited in co-pending US Patent Application No.
63/190,139 (the '139).
1004981 Alternative approaches (or in combination with close-up and macro
photography) - Certain avatar constructions, some examples disclosed in the
'139, can
have their 3D geometries transformed into a plane that is more suitable for
imaging.
This can be done by one or more operations including flattening, unfolding,
disassembling, stretching, sectioning etc. (i.e., their geometries modified)
in order to
facilitate the dosimetric imaging. For example, the 'origami' like avatars
cited in the
'139 can be unfolded. A 3D printed avatar can also be sectioned to better
reveal the
photochromic gradations on the (textured) surface, such that the profile of a
section
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can be imaged normal to the cutting plane. A tab-type 3D construction can he
disassembled. A molded 3D avatar made, e.g., out of a stretchable material can
be
stretched taught around a planar form.
1004991 Mapping - Note that mapping imagery back to a 3D model may provide
diagnostic information enabling better optimization of the instant invention
by
adjusting Nd, tFoG, light sources, etc., and other parameters based on
understanding
how the differences in fluences map to the actual product. See, e.g., Fold
Mapping -
Parametric Design of Origami Surfaces with Periodic Tessellations. Each fold
can be
numbered to allow recombination back to the 3D shape such that the dosimetry
can be
understood on a 3D object. See also the references to 3D models of flluence on
strawberries cited in the '139, namely Simulation of UV-C Intensity
Distribution and
Inactivation of Mold Spores on Strawberries, and Simulation of UV-C Dose
Distribution and Inactivation of Mold Spore on Strawberries in a Conveyor
System.
1005001 Visual inspection - Simple visual inspection of irradiated objects
provides
photochromic feedback and can be used to quickly determine the uniformity of
irradiation (a hallmark of the inventive dry fog approach), and the coloration
can be
correlated to a calibrated dosimeter that travels adjacent to the object
through the
irradiation chamber. The readings on these devices can be correlated to the
surface
portions in an adjacent photochromic object facing the same direction as the
sensor in
the pucks.
1005011 Avatar quality control checks - The surface of the avatars can be read
automatically as it leaves the UVC tunnel (using photogrammetry if using
photochromic materials or using a wireless link if the avatar is
electrooptical). An
analogous method is used in the detection of undesirable objects in a high
speed
manufacturing line (reject systems). "Spray is an optical sorting machine with
the
highest resolution cameras to examine the product on the conveyor belt. The
system is
used to check whole or cut agro-food products: Fruit and Vegetables. Spray can
dispose of colour defects, marked produce and foreign bodies also the same
colour as
the good product. ... Spray is equipped with an air reject system with 176
electrically
controlled ejection valves ... that differentiate unusable produce from
defects
considered second choice. ... Automatic capture of images of rejected products
and
their filing for post-production analysis . ." Raytec Vision Bluelight
Technology,
Ftaytec Vision S.p.A. (Parma ¨ Italy), and available in customized
configurations.
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Such systems can also identify and remove avatars into a separate bin as they
exit the
production line. Another analogous system is described in US9462749
Selectively
harvesting fruits, but for the instant invention, instead of looking for
colors pertaining
to ripeness, the system would look to colors (or gray scales) related to
threshold
dosages on the surface of a dosimetric avatar. For example, a gray scale
(shade of
cyan in the case of cyanotype) that corresponds to an under-dosed portion of
an avatar
(or an area-weighted portion that is under-dosed) would trigger an alarm, slow
the
speed of a conveyor via a control system, etc. Excessive over-dosing (again,
could be
area-weighted) could also trigger an alarm, lower the UVC lamp power via a
control
system, etc. Similarly, there can be other thresholds or mathematical
functions that
trigger suitable responses.
1005021 Mechanical transformations - Radiometer pucks and avatars can be
mechanized to morph into a variety of shapes. For example, a radiometer can
extend
and retract orthogonal surfaces each run through the tunnel to estimate
dosages for a
range of sizes of strawberries.
1005031 Feedback from the dosimetry - Feedback can be used to adjust
irradiation
and fog patterns, as well as alert the operator of any failures thereof If the
manufacturing process causes the release of debris that can affect the
dosimetry, then
measures can be taken to counter this. For example, the dosimeters can be
placed
within UVC grade fused silica (or the PTFE derivative FEP) that can be washed
off
prior to each pass through the tunnel.
1005041 Other approaches in food surface disinfection - Food surfaces have
complex surface topologies that shades a percentage of pathogens from direct
UVC
light. A fog of scattering particles can be directed at the surfaces along
with UVC.
The flow rate can be adjusted to get under flaps, etc.
1005051 In an exemplary embodiment, a food product on a production line enters
a
disinfection station on a first conveyor belt. A second conveyor belt is
spaced a short
distance from the end of the first conveyor belt (either at the same vertical
height or
slightly below, see e.g., the metal chain conveyors from Dorner Mfg. Corp.,
Hartland,
Wisconsin).
1005061 The surfaces of the food product are then charged, e.g., to a positive
potential, e.g., by dip coating. Preferably, the local humidity is controlled
given its
effects on particle size as taught in Atmospheric humidity and particle
charging state
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on agglomeration of aerosol particles, Industrial Sprays and Atomization (ISBN
978-
1-84996-875-1), and Food Powders. Physical Properties, Processing. and
Functionality (ISBN 0-306-47806-4).
1005071 As the food product extends over the gap between the conveyor belts, a
system adaptively directs a cloud of electrostatically negatively charged food
safe
liquid droplets of a predetermined size distribution over a predetermined
scattering
thickness layer(s) on all sides of the food.
(005081 At the same time an algorithm calculates the appropriate UVC
irradiation
spatial/angular/temporal patterns which is directed at the cloud to achieve
the
necessary dosage(s). The UVC scatters through the cloud and irradiates the
food
surfaces, including those in shadow, to achieve the appropriate dosage.
Background
and algorithms for adaptively calculating UVC irradiation levels (and avoiding
overdosing) are taught e.g., in US6656424 Ultraviolet area sterilizer and
method of
area sterilization using ultraviolet radiation, Guidance for Implementing
Action
Spectra Correction With Medium Pressure UV Disinfection, Understanding UV
Monitoring for Air and Water UV Treatments
1005091 Discussion of overdosing (damaging effects of exceeding the necessary
threshold) includes Use of UV-C light to reduce Botrytis storage rot of table
grapes.
100510.1 An exemplary UV monitor with programmable (tunable) ND controller is
Model Q46UV UV254 Turbidity Monitor, from Analytical Technology, Inc.
(Collegeville, PA).
1005111 Exemplary systems include Trojan UV3000Plus Reference Documents -
City of Healdsburg, Installation Instructions and Operating Manual for
Ultraviolet
Water Treatment System - Series B-160 (Wedeco), UV Planning and Design
Principles for DWT.
1005121 A textbook discussing a PID controller design for germicidal UVC
systems Water and Wastewater Infrastructure - Energy Efficiency and
Sustainability
(ISBN 978-1-4665-1786-8); see Appendix E, citing Olsson, G., Instrumentation,
Monitoring. Control and Automation in Water and Wastewater Operations, Lund
University, Sweden, 2010; Araki, M., Control Systems Robotics. and Automation.
Vol II. PD Control, Kyoto University, Japan, 2010.
[005131 MD Controllers are available e.g., from OMEGA Engineering, Inc.
(Norwalk, CT), West Control Solutions (Gurnee, IL) Consulting services for MD
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controllers include Wescott Design Services (Oregon City, OR), and for
multivariable
controllers via Advanced Process Control (Red Lodge, Montana).
1005141 Textbooks on control systems include Control and Insuumentation For
Wastewater Treatment Plants (ISBN 1-85233-054-6), Advanced process control -
beyond single loop control (ISBN 978-0-470-38197-7), Advanced Process
Engineering Control (ISBN 978-3-11-030662-0).
1005151 A food-grade roller conveyor table can also be used, with irradiation
between rollers. Such systems are available from Vande Berg Scales (Sioux
Center,
Iowa). The UVC radiation sources are strategically placed to optimize
illumination of
the shadows given the geometrical design constraints of the production line.
Note that
care is required not to overdose the food and thereby degrade its desirable
qualities.
See citations in the Background, e.g., Effect of Emerging Processing Methods
on the
Food Quality: Advantages and Challenges, ISBN 978-3-030-18190- 1, and
Electronic
Irradiation Of Foods - An Introduction to the Technology, ISBN 0-387-23784- 4.
1005161 An advantage of vertically offset belt conveyors is that the
disinfection
zone can disinfect both the food article as well as the upper conveyor at the
same time
and is easily adaptable for the instant invention.
1005171 After irradiation, a puff of a neutralizing medium can be directed at
the
food surfaces to minimize electrostatic attraction from pathogens and
detritus. The
food can then be packaged (e.g., in plastic wrap, a vacuum sealed bag, a
sealed bag
with a predefined atmosphere, etc.), to avoid further contamination. An
exemplary
neutralizer is MSP Model 1090 Electrical Ionizer from MSP Corporation
(Shoreview,
Minnesota, a division of TSI Incorporated).
1005181 Other arrangements are contemplated in order to irradiate all surfaces
of
the food product. For example, the product can be briefly levitated from
underneath
(like in an air hockey table) with the scatterers while it is enveloped with
scatterers on
the remaining sides, during which the food product is irradiated. Such air
levitation is
found in air tables/conveyors, e.g., available from Pack Air, Inc. (Neenah,
Wisconsin).
1005191 Alternatively, the product can be held in a grill basket like that
used on a
barbeque. The grill basket can also be rotated through the scattering field.
An example
would be the Char-Broil NonStick Grill Basket (Columbus, GA).
[005201 After irradiation, the remaining aerosolized droplets
can be
vented/evacuated, and neutral-charged clean dry air can be blown across the
food item
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at a distance downstream from the irradiation zone so that the dry air does
not
interfere with the scattering particles.
100521] If liquid droplets are unacceptable for contacting certain food items,
then
e.g., CO2 droplets from a dry ice fog can be used, as long as the CO2 is
safely vented
after processing.
1005221 Alternatively, charged food-safe powders can be used for the
scattering
field. After irradiation, the powder residue can be washed-off (if desired) in
a liquid
solution that also neutralizes the surface charge(s). The powder can also form
a
desirable coating that is left on the food article.
1005231 Service businesses ¨ data and analytics can be coalesced at a facility
or via
cloud services and monetized. For example, the machine setting parameters for
a
given food object may be best provided by an expert service, e.g., te0G and Nd
, lamp
positioning, conveyor belt speed, chamber temperatures, fog velocity, etc. for
optimizing the processing of strawberries vs blueberries vs bread. Analysis of
dosimetry, including the dosimetric avatars cited herein can also be provided
as a
service. The data can be gathered from offsite laboratories and uploaded from
data
captured during machine operation at customers' sites Monetization can be one-
off or
based on tiered subscription services. See, e.g., Integrated and Intelligent
Manufacturing - Perspectives and Enablers also citing Cloud manufacturing - a
new
manufacturing paradigm. See also Towards an Automated Optimization-as-a-
Service
Concept, Streaming Machine Generated Data to Enable a Third-Party Ecosystem of
Digital Manufacturing Apps. See also US10618137 Automated constructing method
of cloud manufacturing service and cloud manufacturing system.
1005241 In an exemplary embodiment, a cloud service provides a hub by which
clients manually (or automatically) download optimal UV tunnel machine
settings (or
other devices based on the instant invention) based on the products being
processed at
the factory. Dosimetry data is uploaded to the cloud for analysis and machine
optimization. The contractual arrangement with members can be constructed such
that
the data from the clients can be used in aggregate for further optimizations.
The
analytics are refined over time, such that the factory continues to make
incremental
productivity/quality improvements. Of course, suitable backup systems must be
in
place when the cloud connection is down, hackers attempt to subvert the
process, etc.
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005251 A suitable software platform is available from MachineMetrics
(Northampton, MA), "Any equipment provider, OEM or distributor, can install
MachineMetrics Edge device on a new machine sold to a customer or retrofit any
machine currently in the field. MachineMetrics Edge has the ability to connect
to the
machine's PLC and any additional sensors into the electrical cabinet of the
machine
and allows for the data to be visible to the customer and shared with the
equipment
provider. ... Encrypted data is then streamed to the secure MachineMetrics
cloud
where the data is structured and aggregated to enable visualizations and
analytics for
service teams to monitor. Access to the historical and real-time data is
available
through open APIs. Real-time dashboards, historical analysis, and integrations
with
other systems can be built with these APIs." The Machine Builders' Guide to
Remote
Machine Monitoring.
1005261 Application ¨ disinfecting boxes/crates of food, food trays &
containers ¨
In CFD model development and validation of a thermonebulisation fungicide
fogging
system for postharvest storage of fruit, CFD simulations were generated to
understand
how a fogging disinfectant reached stacked fruits in a box/bin. This approach
can be
leverage in a group of embodiments of the instant invention.
1005271 As an example, a box of known contents (either via QR code, image
processing of the contents, etc.) is engaged by a system that temporarily
seals the
openings, evacuates the air via the sealed openings to a predetermined
pressure or
over a predetermined time, fills the interior of the box via the openings with
electrostatically charged puffs of water spray having a predetermined droplet
distribution size in the submicron and micron range, inserts UVC wands and
irradiates
the targets with UVC using an array of UVC LEDs until reaching a predetermined
dosage based on time or feedback, then evacuates the droplets, and finally
tilling the
interior with dry air to complete the process.
1005281 Many options are possible. For example, the contents of the box can be
imaged (e.g., inserting cameras or via penetrating radiation such as THz, x-
rays, etc)
to determine an optimum irradiation process that includes adapting one or more
of the
following parameters: distribution size of the scatterers, the fluid
pressure/timing/distribution of the spray, the number/timing of
evacuation/filling/itradiation cycles, the UVC
intensity/spatial/angular/timing
characteristics of the individual radiators, mechanical movement of the
product by
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effectors, etc. UV-grade optical fibers can telescope in-and-around the target
to
enhance irradiation coverage. In fact, UV grade optical fibers/rods (e.g., end-
emitting
or side-emitting depending upon the application) can be formed in a thin sheet
interspersed with manifolds fitted with nozzles/perforations to emit
scattering
elements as shown in the complementary views of Figures 9a and 9b. Note that
light
rays emitted from the side emitting fibers, while somewhat diffuse, are still
vulnerable
to surfaces in shadow adjacent to the plane of the fiber/manifold array
without
additional scattering spaced apart from the fibers.
1005291 Side emitting fibers for use with UV are discussed in
Pligtmutigi.n..A.r.g45.
Where You Typically Cannot Get Light, Design and Modelling of Novel Waveguide
and Light-Emitting-Diode-Based Photoreactors, Photocatalytic activity on TiO2-
coated side-glowing optical fiber reactor under solar light. UVC grade side-
emitting
fibers can be made from fused silica fibers (or rods) with a special surface
treatment,
see Performance Assessment of Novel Side Firing Flexible Optical Fibers for
Dental
Applications. Fused silica rods are available Heraeus Quarzglas GmbH & Co. KG,
Heraeus Conamic (Kleinostheim, Germany), and fused silica fibers are available
from
T FONT Fiber Optics Inc. (Williamsburg, VA).
1005301 A plenum can be constructed within the box that directs air underneath
each target so as to lift the target temporarily off its resting surface
within the box in
order to irradiate the target's surfaces that normally contact the box and
therefore
would be in shadow. The same (or additional) puff of air can also be used to
move the
surfaces of leafy vegetables to better illuminate target surfaces in shadow.
1005311 Of course, other processes can be added, such as injecting into the
boxes
(or the targets themselves) any other agents needed for disinfection or other
purposes
(e.g., ripening). Other sensors can be used to optimize the efficacy of a
given process
as is known in the art, including the art cited herein.
1005321 An exemplary high throughput fogging system with ¨ 1 micron particle
size is the Sanomist from Sanitech Innovations (Juinagar, Navi Mumbai, India).
1005331 Food trays & containers are also considered, where the tray or
container
holds e.g., prepared liquid and/or solid food, and the desire is to stop the
progression
of microbial growth by using low dosages of UV/visible light, e.g., as cited
in
Applications of Light-Emitting Diodes (LEDs) in Food Processing and Water
Treatment. Because the food was originally prepared with low microbial counts,
the
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dosage strategy is not the same as that used, e.g., to reduce pathogens by 4-
or 5-log in
water. In fact, with prepared foods, the cited article suggests that some
foods are
degraded by high doses of light. The article suggests that wavelengths closer
to blue
may be sufficient to control microbial growth. In that case, existing clear
PET or
PETE (polyethylene terephthalate) containers have suitable light transmission
(see
e.g., Fig. 2 in PTS 2014 27 437-448 Quality Changes of Extra Virgin Olive Oil
Packaged in Coloured Polyethylene Terephthalate Bottles Stored Under Different
Lighting Condition). These containers can have holes by which scattering vapor
can
be injected (periodically) in order to scatter the light incident on the clear
packaging.
[00534] Trays used for food contact, whether disposable or not, are generally
open
to the air. In an exemplary configuration, these trays are stored in a
refrigerated case,
and periodically illuminated with germicidal light while they are fogged with
a food-
safe vapor of the appropriate scattering size.
[00535] Whether box, crate, tray, or container, in one embodiment, the
geometry is
such that the food is supported by point contacts (e.g., triangular
corrugations) such
that some of the vapor and light is guided between the corrugations in order
to contact
the backside of the food (in addition to contacting the front side of the food
article)
and allow draw-through of the vapor from one side to the other. Specially
fabricated
refrigerated cases can be designed to periodically direct vapor and light
through the
corrugated channels, while also directing the vapor and light onto the top
surface. In
some instances, there is no need for vapor to contact the top of the food
article, only
germicidal light (for those food articles where sufficient light contacts the
top surface
of the food without requiring scattering).
[00536] In any of the configurations, the vapor can also contain a small
amount of
food-safe biocide so that moisture from the vapor does not cause microbial
growth.
[00537] Application ¨agriculture via wave energy scattering to enhance kinetic
processes (process intensification) such as germicidal, photosynthetic, fruit
ripening,
etc. (on any unicellular/multicellular eukaryote that responds to wave energy,
plant
or animal) grown for food, aesthetic value, soil conditioning, filtration,
toxin
reduction, climate control, shade, enhanced gaseous (e.g., CO2, 02) exchange,
as well
as for providing medicines, fuel/energy, and other
residential/commercial/industrial/military products and purposes -
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005381 Germicidal - "Gadoury's vineyard setup uses an array of 75 to 100 lamps
¨ glass tubes similar to fluorescent lamps but without the coating that
household
lamps use to shift the wavelength into the safe zone ¨ combined with
reflectors,
inside a shield that carries the lamps over the canopy. "It's not a death ray,
but it will
give you the mother of all sunburns, and if you look directly at it, it could
blind you,"
Gadoury said, adding that the vineyard array is designed to prevent worker
exposure
to UV with shields, so only the glow is visible. "When you see these things
going
through the vineyard at night, glowing in the dark, it's sort of
otherworldly." Inside
the array, there are enough reflectors to create a fog of light particles that
bounce
around and hit every canopy surface. Engineers at the Lighting Research Center
have
worked on how to optimize that light spray and how to size it for delivery,
Gadoury
said. if you want to pull an array behind a tractor at 2 miles an hour, you
have to make
it long enough and bright enough to get sufficient exposure at that rate. A
robot array
that crawls through a strawberry field, on the other hand, can be much
smaller, since it
al so moves much slower" A shot in the dark - Nighttime applications of
ultraviolet
light show promise for powdery mildew control. In an exemplary embodiment,
such a
system is fitted with a scattering generator to increase the fluence to
surfaces in
shadow. Using the example in the article about vineyards, scattered UVC (or
other)
can be directed at any part of a grape plant, including vines, leaves, fruit,
etc. that are
susceptible to grapevine downy and powdery mildew. See also US20200134741
Controlled Agricultural Systems and Methods of Managing Agricultural Systems,
US8299445 Lighting apparatus for controlling plant disease, US9867894
Germicidal
apparatuses with configurations to selectively conduct different disinfection
modes
interior and exterior to the apparatus.
1005391 Photosynthetic ¨ this has been discussed elsewhere herein.
1005401 Fruit ripening/other - "The positive effect of LED lighting on the
acceleration of ripening in bananas was greatest for blue, followed by red and
green.
Under the irradiation of LED lights, faster peel de-greening and flesh
softening, and
increased ethylene production and respiration rate in bananas were observed
during
storage. Furthermore, the accumulations of ascorbic acid, total phenols, and
total
sugars in banana fruit were enhanced by LED light exposure." Effect of LED
irradiation on the ripening and nutritional quality of postharvest banana
fruit.
"Researches have shown that UV-C could induce resistance of fruit and
vegetables to
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postharvest spoilage as well as delayed the ripening process for extending the
shelf
life [32]. Further UV can induce bioactive compound production (polyphenols,
anthocyanin) in fruits [33]. Moreover, when used at an ideal level, UV-C light
induces systemic acquired resistance or buildup of phytoalexins to prevent
further
invasion [34]. Most likely, that play a major role in the disease resistance
of many
plant systems and activates genes encoding to produce pathogenesisrelated
proteins
[35, 36]." Postharvest Ultraviolet Light Treatment of Fresh Berries for
Improving
Quality and Safety.
1005411 There may be some applications where a spatial intensity gradient is
desirable. For example, when illuminating the undersides of leaves in a
vineyard at
night, from an energy perspective, it only makes sense to cast the
illumination at
leaves and not the open areas adjacent to the leaves. Thus, in one exemplary
embodiment, an array of LED illuminators is mounted on a robot, where a camera
is
used to turn on only those LEDs in the array that will illuminate a leaf. The
LEDs
can be statically mounted in a flood-type arrangement, or groups of LEDs can
each
be mounted on a computer controlled gimbal. In another exemplary embodiment,
multiple LED groups direct their beams towards one target, while single LED
groups
each irradiate unique targets.
[005421 =Note that the source of wave energy ( e.g., UV source) and the source
of
scattering particles can be collocated, or they can be separated, and their
deployment
can be coordinated or not. Coordination can be tightly controlled or quite
loosely
controlled via wire-based links ( e.g., USB, ethernet, etc.) and/or wireless
links
(Bluetooth, WiFi, LiFi, etc.), i.e., communications channels. For example, on
a farm,
prevailing winds may make it difficult to precisely direct the scattering
field, and in
such circumstances the scattering field may simply 'flood' the target zone. In
another
embodiment, if winds are too strong, a more tightly controlled system may
employ
denser scatterers whose scattering performance is adapted by adjusting the
wave
energy beam(s) and/or relative locations between the sources of illumination
and
scattering. The projecting elements for the wave energy and the scatterers
each may
be gimballed for best coordination. The system may also deploy one or more
reflectors in the far field to redirect wave energy that misses the target
back towards
the target(s). Alternatively, some wave energy may be focused at a reflector
in the far
field such that the scattering field is illuminated from such a vantage point
(in
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addition-to or instead-of illumination without the use of the reflector). A
target may
also include a reflector (diffuse and/or specular) to aid in the backscatter
of wave
energy. Multiple systems can be deployed with their efforts coordinated by
communication with each other and/or through a common agent. An exemplary
agent
can be one or more computers adapted/programmed for such purposes (local or
cloud-
based), and/or one or more human technicians.
1005431 Now, the geometry of surfaces in shadow can be predictable (e.g., HVAC
coils) or unpredictable (e.g., the undersides of leaves in a vineyard
fluttering in the
wind, the daily changes to leaf arrangements in a greenhouse, or a random
arrangement of equipment in a hospital room). The aerodynamics of a given
application may allow for a static setup or may require robotic/human
articulation for
the dispensing of scattering particles and/or the UVC. The scattering angles
required
for a given application may suggest a single-sized collection of scattering
particles or
multiple sizes (either together or via consecutive applications), or even a
pass
without any particles, where the application of particles is only used for
specific
locations (and specific conditions). The size of the particles (their
distribution in
space, etc.) will determine the degree of forward/side/backscaftering The
desired
amount of each can be determined for a given application Also, the proportions
between one or more of forward/side/backscattering can also be used as part of
the
feedback system for determining dosage and/or adjusting the application
conditions.
These proportions can also determine the shapes of scattering particles (e.g.,
if they
are deforming from spherical due to local conditions). Spherical beads can be
used to
calibrate the system. So, if the system is designed/characterized based on
spherical
scatterers, the change to non-spherical shapes will impact the dosages, as the
proportion of forward/side/backscatter will change.
1005441 A preferred simulation strategy would start first with simple
geometric
embodiments. For example, parallel surfaces, then various parametrically-
defined
curved and polygonal surfaces, pinched surfaces - all of various aspect ratios
(depth/gap). This is similar to how turbulence and pressure drop are
characterized for
various plumbing elements. In fact, turbulence and pressure drop are
calculations that
are helpful in the instant invention in order to understand how the media and
scattering particles flow around the target surfaces. Similarly, data used for
insecticide foggers (including electrostatic versions), e.g., application
variables as a
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function of crosswinds, serve as one of the baselines for inputs to the
simulations and
real world tests. Ultimately, for surfaces in shadow, the goal is to get
scattering
particles near the surfaces so that the UVC rays can find a path to the
surfaces which
would be impossible (or of such low dosage) otherwise. Note that the above
approach is applicable to both gaseous and liquid media, e.g., water-bubbles-
in-air
and air-bubbles-in-water. The simulations should be run based first on
spherical
particles, and then on various degrees of non-sphericity based on
characterization
during testing (or simulation). Also, key to the approach is determining
whether the
appropriate dosage has been delivered, which includes selecting the type of
feedback
elements and their location for use in a control system. For example, COMSOL
simulations may show that over the range of input conditions, one or more
(important) locations may receive the lowest dosage compared to all other
locations.
Therefore, placing feedback elements at these locations (e.g., a wireless UVC
sensor
in a vineyard supplied power by a solar panel and battery system) ensures that
once
this sensor meets the dosage requirements, all the other surfaces meet the
requirements as well. In another embodiment, the system has an attached wand
element that is used to sense dosage in the far field Other feedback elements,
such to
measure atmospherics (wind speed, humidity, temperature, etc.) can also be
wirelessly located (indicating the best conditions for application and/or
aiding in the
configuration of adaptive systems) or attached to the illumination or
scattering
system(s). The scattering field also needs to be statistically predictable so
that
dosages can be reasonably assured by providing a consistent range of angles
from the
scattering field. While an appropriate amount of scattering can be obtained
with a
very narrow depth of a given concentration, it may also be appropriate to use
a
deeper field with an adjusted concentration to result in about the same level
of
performance (which may also require an adjustment to the illumination
conditions).
From a physics perspective, a deeper field would have higher entropy than a
narrower field, and so the deeper field would have more available microstates
and so
be a more favorable (stable) configuration. Note that the above methodical
approach
is much different than simply injecting CO2 bubbles (water medium) based on
the
hope that e.g., within a range of bubble diameters from 1 to 100 microns some
level
of performance will be met.
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1005451 In an exemplary embodiment, the fog field is modified after its
emission
into space (e.g., a room, a greenhouse, a vineyard, etc.), e.g., via one or
more streams
(e.g., fan-shaped streams, cylindrical streams, etc.) of clean, dry compressed
air, so
that there is one or more clear paths through the fog to allow the UV beam to
travel
farther into a room before reaching the scattering fog, thereby increasing the
UV
intensity at select locations in the far field. Alternatively, the fog field
can be
generated with gaps, e.g., linear stripes, or circular rings. These fields can
also be
scanned across the targeted surfaces in various patterns, e.g., zig-zag,
epicyclic,
random, etc. As an aside, note that different aerosols can be utilized at the
same time
(or in some temporal order) e.g., one with more forward, side, and/or
backscattering
than another. Air streams can also be used to increase the stochastic nature
of the
process, increasing the chances of irradiating surfaces in shadow that were
previously
missed. Note that flow changes are contemplated based on positive pressure,
negative pressure, and alternating positive/negative pressures.
1005461 As mentioned, the scattering approach can also be used in other
horticultural applications, such as in stimulating incremental photosynthesis.
1005471 In a simple embodiment, a single ITVC LED (-- 280nm) or array thereof
and a single ultrasonic mesh atomizer are combined to form a modular unit to
disinfect surfaces in shadow. In a second simple embodiment, red (¨ 660nm) and
blue (¨ 450nm) LEDs (see e.g., the Horticulture Reference Designs from Cree,
Durham, North Carolina) are used with a small array of ultrasonic mesh
atomizers
(and the necessary aerosol shapers/mixers/directors) to stimulate plant growth
including leaves in shadow. Note that to help the penetration of light into
surfaces of
shadow, the aerosol can be directed in a strong puff to move the surfaces (or
the hood
can be equipped with an evacuation feature that first evacuates some of the
air
adjacent to surfaces in shadow after which the evacuation is stopped and the
aerosol
is then directed into the shadowed surfaces, somewhat akin of what is
discussed in
the evacuation/filling cycles of steam sterilization (CFD investigations of
steam
penetration, air-removal and condensation inside hollow loads and cavities,
CFD
simulation of the inactivation of Geobacillus stearothermophilus on dental
handpicces), also contemplated for the instant invention with respect to
multiple dry
fog scattering cycles) . A strong puff of air can be used to separate surfaces
before
the application of the aerosol. For example, in the case of plant leaves
shading each
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other, the effects (positive like increased light interception and mass
transport, and
negative like leaf/branch damage) of air flow ( e.g., from a leaf blower) to
separate
leaves must be considered. See e.g., Review - Wind Impacts on Plant Growth,
Mechanics and Damage and Foliage motion under wind, from leaf flutter to
branch
buffeting. Note that the aerosolized water can be a mixture of 'dry' and 'wet'
particle
diameters depending upon how much wetness (if any) needs to be transferred to
the
plants. The scattering of light is more strongly influenced by the smaller
diameter
'dry' aerosols, and so much larger diameter 'wet' aerosols can be present
without a
significant change to the scattering characteristics (see the single particle
Mie
scattering of the 0.5p and 5.01.t water droplets herein). Of course, using the
smaller
diameter wet particles, it may be possible to sufficiently scatter light
depending upon
its wavelength without resorting to aerosolizing dry particles as well.
Certain aspects
of these concepts, as applicable, can be scaled to larger sizes (e.g., crates,
rooms,
tunnels, greenhouses, vineyards, etc.).
1005481 Purging aerosols before/after irradiation/disinfection - In an
exemplary
aerosolizing system, a first air mover is used to aerosolize e.g., distilled,
or deionized
water (that may be treated with surfactants, disinfectants, etc.). The source
air (e g ,
from a compressor) may or may not be filtered depending upon the system
requirements. Exemplary reasons for filtering include (a) the degree to which
UVC is
more efficiently coupled to the aerosol with pre-filtered air, (b) the degree
to which
the aerosol particles have less absorption with pre-filtered air, (c) the
degree to which
the aerosolizing generator works more efficiently with pre-filtered air, and
(d) dust
removal to avoid clogging the fine particle filtering used for evacuation
after
irradiation/disinfection as described below.
1005491 Prior to aerosolization/irradiation, the air may be evacuated/filtered
to a
predefined degree to enable particles to better penetrate cracks and crevices.
Also,
after the irradiation/disinfection, any remaining aerosolized liquids may be
evacuated
(similar to that cited in Altapure AP-4 specification sheet for a standalone
system, by
pulling through one or more fine particle HEPA-type air filters by a (high
volume)
secondary air mover (e.g., ) to remove aerosolized particles within a desired
range of
sizes, which is a function of the filter's size rating (similar to what is
found in an
IIVAC system in a building or on an airplane). The air mover must be sized for
the
flow rate required in accordance with the evacuation time requirements,
accounting
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for the filter's pressure drop that increases as more particulates are
trapped. In order to
reach the desired filter efficiency, the air in a given room may need to be
turned over
a number of times. See the overall discussion of air filtering re: COVID-19,
including
MERV, HEPA, and ISO 16890 ratings, e.g., in Evaluating and Reducing the Risk
of
Airborne COV1D-19 Infection Indoors. The article discusses in detail the
effect of
particle sizes in the transmission of the SARS-CoV-2 Coronavirus (or any
similarly-
sized pathogen), including the effects of vortices and eddies in air movement.
[00550] It is also important to note that e.g., a surface disinfection system
according to the instant invention will also have a remedial effect on
airborne
pathogens since UVC travels through the air (more generally, travels through
the
media, be it a gas like air, or a liquid like water). According to the above-
referenced
article, aerosolized SARS-CoV-2 Coronavirus within droplets having aerodynamic
diameters between about 1 and 10 are the most effective for transmission
(the virus
itself is < 10.
[00551] Particles (aerosolized droplets contain the virus) between 1p. and 10g
in
diameter are larger than the ¨ 0.28 wavelength of UVC light, and this is
important
for multiphysics simulation purposes to understand how an entrained virus (or
collection thereof) is irradiated within the droplet. Certainly, a more
homogeneous
irradiation field (resulting from a scattering field of the instant invention)
has a greater
likelihood of intercepting a virus-laden droplet, especially for those
droplets buoyed
for long times, e.g., by eddies created by vortices from an HVAC system in a
room or
on an airplane (see Fig. 1 of Evaluating and Reducing the Risk of Airborne
COVID-
19 Infection Indoors).
[00552] The evacuation system cited above can also be fitted with a UVC
irradiation system to further reduce the number of aerosolized pathogens (in
addition
to trapping by the fine particle filtering). Such a system can be enclosed
within a
chamber of the device, e.g., using PTFE, a diffuse reflector material known to
be very
highly reflective of UVC, such as Gore DRP material (DRP Literature (Gore), W.
L.
Gore & Associates, Inc., Electronic Products Division, Newark, Delaware). Of
course,
such a highly reflective surface must be kept clean to maintain its high
reflectivity. In
fact, maintenance is a necessary element to ensuring consistent process
intensification, thus the need e.g., for periodic filter and lamp replacements
used to
treat gases and liquids. See e.g., An Evaluation Of Ultraviolet Germicidal
Irradiation
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(UVG1) Technology In Health Care Facilities for a discussion on maintenance of
an
UVGI air filtration system. "Fixtures need to be designed to allow easy
cleaning and
maintenance of louvers, lamp, ballast, and reflector" (Maintenance Of Upper-
Room
Germicidal Ultraviolet (GUY) Air Disinfection Systems For TB Transmission
Control)
1005531 Note that the purging/evacuation of aerosols via filtering also helps
filter
the air of pathogens/toxins that have been aerosolized. Filters, like N95
masks, can be
irradiated to disinfect so long as the filter material does not quickly
degrade under the
necessary irradiation.
1005541 "The challenge to effectively sterilize dental handpieces lies in
their
construction with geared or turbine drive mechanisms and lumens (0.9-2.3mm
diameter) carrying air and water that restrict access for cleaning and steam
ingress for
sterilization. The European standard for benchtop (tabletop) steam sterilizers
(4)
describes three different processes by which these benchtop machines can
remove air
to allow direct access of saturated steam to the surfaces of surgical
instruments. Type
N, which is a non-vacuum and passive air displacement process, type B and S,
which
achieve air removal using fractionated pre/post-vacuum phases and special
cycles,
respectively. Manufacturers of both sterilizers and dental handpieces
recommend that
this equipment be sterilized using a vacuum process, (for example,
instructions for
handpiece sterilization (5) and benchtop steam sterilizers(6)). Non-vacuum
sterilizers
are still widely used Worldwide (7,8) and in the UK (9,10)" Failure of non-
vacuum
steam sterilization processes for dental handpieces. By analogy, in one
exemplary
embodiment of the instant invention, a vacuum is used to remove air prior to
the
injection of the dry fog scattering droplets. The dry fog thus fills the
micro/macro-
sized voids, and thus enables the dry fog to be in the field of view of
microbes,
providing a path for scattered light to travel between source and target. As
in some
steam sterilization systems, the evacuation/filling cycles can be performed
multiple
times to increase the disinfection of a given set of objects. See also the
steam
sterilization references cited herein (includes CFD simulations). Note that
the optimal
amount of air removed (the degree of the vacuum) in one exemplary embodiment
is
determined via one or more of simulation and testing. Lesser vacuums result in
shorter evacuation times that lead to higher factory throughputs. Deeper
vacuums
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may lead to increased dry fog droplet impingement velocities, which must be
balanced vs deeper penetration into the voids.
[00555] Applications ¨ photodissociation, photocatalysis, and dosing
1005561 With respect to the photodissociation (also known as photolysis,
photodecomposition, and photodegradation) of chemical pollutants, instead of
citing
UV dosage, the UV intensity is related to a chemical reaction (degradation)
rate
(Calculating photolysis rates and estimating photolysis lifetimes. Rates of
Direct
Photolysis in Aquatic Environment). The reaction rate can be linear or non-
linear with
intensity (Decomposition of Inorganic Fulminates).
1005571 In the case of photocatalysis, in otherwise favorable conditions,
the
conversion rate is linear with intensity to a threshold value, after which the
rate varies
as the square root of the intensity (Basic Principles. Mechanism. and
Challenges of
Photocatalysis).
1005581 Proxy illumination and light sources ¨ Given the citation of the light
proxy
above, it should be noted that the scattering field can be illuminated by a
proxy visible
light so that the operator has a sense of how well the targets are illuminated
by the
functional irradiation source(s), which are often invisible, such as a INC
light,
ultrasonic waves, or electron beams. Of course, the scattering angles are
dependent
upon wavelength, so this must be considered when using proxy illumination,
i.e.,
532nm green laser light scatters differently than 445nm blue laser light and
280nm
UVC light.
1005591 In an exemplary, a proxy illumination feature is added to the UVC
scattering system of the instant invention. Two visible light laser pointers
serve to
inform the operator of the distribution of scattered UVC rays (since UVC is
invisible).
In one embodiment, the laser turns off prior to the generation of the
scattering field if
(a) backscatter would be dangerous to the operator, (b) the scattered laser
light would
not be visible, (c) to conserve power. In another embodiment, the lasers are
fitted with
holographic/diffractive alignment pattern generators to project markings on
the
target(s). In yet another embodiment, each UVC source is paired with a visible
source
of the same beam geometry in order to provide feedback more accurately to the
operator (human and/or robotic).
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[00560] The system comprises a computer controlled scattering field generator
that
emits a field of appropriately sized scatterers. The field is projected based
on certain
spatial/temporal limits. The reference beams are laser pointers.
[00561] The brightest laser pointers are said to be green, operating at 532nm
(Laser
Pointer Color Differences - Brightest Burning) and are available e.g., from
Berlin
Lasers (dba Berlin Optic (HK) INT'L Group Limited, Kowloon, Hong Kong; see
532nm Green DPSS Laser Diode Module. Green Laser Modules Berlinlasers) and
with predefined alignment patterns from Laserglow Technologies (Toronto, ON,
Canada; see Laserglow Technologies _Industrial & Scientific Lasers
_Laserglow).
Note that 445nm blue lasers are available in higher powers, but the eye is
less
sensitive to blue than green, and safety is an issue with higher power (Laser
Pointer
Safety - Different lasers' hazards compared).
[00562] In one embodiment, the laser pointer and LIVC sources are set at fixed
angles relative to the large scattering field. This is suitable for a handheld
device.
Other embodiments can be constructed for operation over a range of angles,
available
via mechanically turning a knob or via an adaptive motorized solution See
e.g.,
U58025428 Assembly of liqht emitting diodes for lighting applications Note
that the
LEDs can be rotated as a group, or a rotatable mirror can be inserted in the
optical
path. Given that UVC mirrors are somewhat lossy, the rotation of the LED array
is a
preferred embodiment with the proviso that the LED heatsinking is not
compromised.
[00563] Various source configurations are contemplated to aid in uniform
illumination and shadow minimization/elimination via multiple light sources,
ring
lights, projectors, under leaf lighting, LEDs, and adaptable LED arrays.
[00564] Windows - The window protecting the LEDs (or other sources) must
maximize transmittance (to the extent practical) for the relevant wavelengths
and must
have the appropriate hardness and environmental qualities (temperature range,
sealing, etc.) as needed for the application. Further, for some applications,
the window
must remain clear of foreign objects and debris (FOD) and fog. An example of
such
for EM waves is an airstream as discussed in US20160166138 Image pick-up
window
defogging function-equipped built-in camera hand piece. In other exemplary
embodiments, the window is 'coupled' to the system to ensure maximum
throughput.
1005651 Continuous steady illumination, temporal/spatial gradients - In some
instances, there may be an advantage of pulsed illumination over continuous
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(Enhanced inactivation of E. col i by pulsed UV-LED irradiation during water
disinfection, Comparative disinfection efficiency of pulsed and continuous-
wave UV
irradiation technologies, An Approach to Standardize Methods for Fluence
Determination in Bench-Scale Pulsed Light Experiments).
1005661 Also, there may be some applications where a spatial intensity
gradient is
desirable. For example, when illuminating the undersides of leaves in a
vineyard at
night (Robots Armed with UV Light Fight Grape Mildew), from an energy
perspective, it only makes sense to cast the illumination at leaves and not
the open
areas adjacent to the leaves. Thus, in one exemplary embodiment, an array of
LED
illuminators is mounted on a robot, where a camera is used to turn on only
those
LEDs in the array that will illuminate a leaf. The LEDs can be statically
mounted in a
flood-type arrangement, or groups of LEDs can each be mounted on a computer
controlled gimbal. Such gimbals (including systems with gyro stabilization)
are
available e.g., from Merio (Saint-Restitut, France).
1005671 In another exemplary embodiment, multiple LED groups direct their
beams towards one target, while single LED groups each irradiate unique
targets.
1005681 Beamforming - in various embodiments, the irradiation beam(s) is/are
constructed to scatter light most effectively through the scattering field to
the
target(s). As cited, exemplary embodiments include the formation of beams into
streams (narrow beams), showers (wide beams), rings (annular beams), sheets
(linear
beams), etc. Beamforming optics include lenses, lens arrays, lenticular
arrays,
reflectors, holographic/diffractive elements, etc. Such devices are available,
e.g., from
Edmund Optics Inc. (Barrington, NJ) and Thorlabs (Newton, NJ), including
custom
designs via their application staff. Off the shelf and custom UVC reflectors
are
available from uv-technik international ltd (Luton, Bedfordshire, United
Kingdom).
Custom UVC lamp/reflector systems are available e.g., from American Air 8z.
Water , Inc. (Hilton Head Island, SC). Molded LED reflectors are available
from
OSA Opto Light GmbH (Berlin, Germany; see Research realizes innovation in
fabricating reflective coatings for high-power UV optics (MAGAZINE) LEDs
Magazine). More on wave energy sources and beamforming can be found in the
'071,
section 16.1.10. Illumination sources and beam forming.
[00569.1 Feedback re: light sources - Other embodiments use sensor feedback to
determine distance to the targeted surface and then automatically adjust the
angles
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For the distance measurement portion, see e.g., the use of a laser pointer in
US8138938 Hand-held positioning interface for spatial query. and simply a
camera in
US8467579 Apparatus and method for estimating distance and position of object
based on image of single camera. The fields of laser trackers, ballistic
targeting
systems, and drone camera gimbals are well known in the art and can be adapted
for
use in the instant invention. Processed data then controls custom computer
controlled
gimbals (including systems with gyro stabilization) that are available e.g.,
from
Merio (Saint-Restitut, France) and top-tier drone manufacturer DJI (Nanshan
District,
Shenzhen, China). Laser trackers and object scanners are available from
Automated
Precision, Inc (Rockville, MD), "API's RAPIDSCAN ultra-high dynamic range, 3.2
mega-pixel, stereo imaging, hybrid optical sensor captures a 3D point cloud of
the
part within its large field of view."
1005701 An exemplary feedback approach for the operator is to visibly
illuminate
the scattering field so that the operator can see the extent of the 3D field,
thus
providing an understanding of what is being illuminated with the invisible UVC
field,
and then adjusting the position of the scattering UVC system accordingly. In
one
exemplary embodiment, each ITVC emitter can be mechanically coupled with a
visible emitter of similar beam characteristics.
1005711 The use of cameras to detect particle/fog uniformity, including use of
tracer particles are discussed in Development of a High Irradiance LED
Configuration for Small Field of View Motion Estimation of Fertilizer
Particles, The
effect of spray volume and auality on handgun delivery of pesticides to
greehouse
plants, Analysis Of Optical Density Of Electrostatic Spray On Apple In Winter
And
Summer Season, Optimization of spray application technology in ornamental
crops,
Tracer techniques for the comparison of sprayer performance. Tracer particles
(e.g.,
fluorescent) can be used as is known in the art of fogging systems as in order
to
understand the distribution of aerosols at a target site (e.g., a crop plant).
1005721 Automated arm-mounted UV disinfection robots are available from
Enabled Robotics ApS (Odense, Denmark), "UVx1 is an automatic UVC light
solution designed for disinfection of bacteria and virus hotspots. ... The
UVx1 is
supplied as an application kit for direct and easy fit on your ER-LITE or ER-
FLEX
robot. ... The ER-FLEX is a robot series which is optimized for easy changing
of
applications on the robot. You can easily change hardware and fixtures to
customize
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it for almost any application in your environment. .. The ER-ONE Dynamic
Position System enables easy calibration between the robot and markers in the
environment." In an embodiment, the above system is also fitted with a dry
fogger,
or if desired, coordinates with a dry fogging robot (water-only or with
disinfectants)
such as the Sherpa-BD and Sherpa-W from Sherpa Mobile Robotics (Haguenau,
France), "SHERPA MOBILE ROBOTICS joined forces with DEVEA and developed
an autonomous and certified disinfection system. Resulting from a
collaboration
between two renowned industrialists, ... Based on the virucidal process
certified
NFT 72-281, this disinfection robot combines the advantages of SHERPA robots
(autonomy, safety, versatility) and the proven DEVEA disinfection process
(centrifugation, DRY fog diffusion, microbiological disinfection)." DEVEA
(Saint-
Etienne-de-Monduc, France). Custom integration and software development for
mobile robotics is available from Fresh Consulting (Bellevue, WA) ,
"Autonomous
mobile systems come in all shapes and sizes, from wheeled to walking robots,
drones, and even large industrial vehicles. The robotics team at Fresh has
worked
with them all. Whether you are building something custom, looking to modify
something for autonomous activities, or need an engineering audit of your
existing
system, our team can help."
[005731 Geometric relationships between nozzle/illuminator/sensor, feedback
and
dosage control - A fluid scattering field can be thought of as a stochastic
system, and
therefore determining that minimum dosages are achieved without overdosing is
important. For example, scattering clouds can be affected by environmental
factors
like ambient airflow/wind.
1005741 An exemplary feedback approach would be to extend sensor-stalks out a
distance from the nozzle, where each stalk measures the intensity at a given
angle in a
location close to the target(s). Ideally the number of sensors is minimized to
meet
dosage/throughput requirements at minimal cost and maximum reliability.
1005751 Alternatively, a vvireframe structure made of reflective material
(e.g.,
Teflon for use with UVC) can be extended out a distance from the nozzle, and a
sensor array adjacent to the nozzle can estimate the intensity in the far
field. The size
of the structures extending from the nozzle should be minimized to ensure
sufficient
flow of particles and adequate irradiation.
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005761 Another exemplary approach measures backscatter as a proxy for the
forward scatter component.
1005771 In yet another exemplary approach, the system is designed for close
operation to the target(s). If handheld, a wand-like structure (like that used
on some
fogging systems found in the references herein) can propel the scatterers
close to the
targets, and the illuminators can be mounted at predefined locations between
the
handgiip and the end of the wand. One version would have the illuminators at
the end
of the wand surrounding the nozzle(s), and in another version a light guide
(e.g., UV
grade fused silica rod) would transmit the light (UVC and any visible proxy
light) to
the end of the wand where an optical arrangement is attached to distribute the
light as
desired. Different optical attachments can be used for predefined beam
patterns, just
as different nozzles can be used for predefined scattering field geometries,
forming a
modular device.
005781 In all instances, the feedback can be used to adjust the illuminator(s)
and/or the flow characteristics of scattering particles to ensure proper
dosage. Further,
the device can provide feedback to the user as to the relative speed between
the
system and the target(s) since dosage is the product of intensity and time A
display
on the system can depict the nozzle in the center, and an annular zone (for
radial
movement) or rectangular zone (for lateral movement) around the nozzle that
indicates whether the relative speed is appropriate in the direction of
movement. For
example, consider an electronic version of a 'Bull's Eye Circular Level',
where the
bubble shows radial velocity relative to zero when the bubble is centered. To
ensure
proper dosage, the radial velocity indicator must be within a certain annular
region.
Another analogous display would be a helicopter's hover indicator such as that
disclosed in US20060238377 Integrated hover display with radar altitude
predictor for
indicating height above ground. Audio and/or haptic feedback can also be
provided in
addition to visual indicators. See e.g., Audio-Haptic Feedback in Mobile
Phones.
1005791 In any event, the intensity can be adapted for motion that is too slow
(by
dimming the irradiation) but cannot adapt to movement that is so fast that the
highest
irradiation power cannot provide adequate dosages.
1005801 Determining relative speeds between a stationary irradiation source
and a
food article on a conveyor belt is trivial, but in order to determine the
relative speed in
a portable arrangement is more complex.
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1005811 On mobile phones, GPS is often used to determine speeds, although its
positional accuracy has been measured between 7 and 13 meters in an iPhone 6
in an
urban environment (Smartphone GPS accuracy study in an urban environment), and
since speed is distance divided-by time inaccuracies in position lead to
inaccuracies in
speed. One can also use range sensing (Active and Passive Range Sensing for
Robotics) to determine distance and then calculate speed from changes in
distance
overtime. A number of other methods can be used to estimate speed (velocity),
e.g.,
signal strength (Vehicular Speed Estimation using Received Signal Strength
from
Mobile Phones), transit time (rain Velocity Measurement with Optical Sensors
and
US4685093 Speed measurement device), inertial sensors (Bat Swing Analysis in
Cricket, Low Cost Inertial Sensors for the Motion Tracking and Orientation
Estimation of Human Upper Limbs in Neurological Rehabilitation) and others
like
cameras, LIDAR, and radar (A New Velocity Meter based on Hall Effect Sensors
for
UAV Indoor Navigation)
1005821 Target power received at a given location ¨The power received at a
target
location when transmitted from a UVC source a distance away through a
scattering
path data can he modeled by using the Non-Line-Of-Sight (NT ,OS) algorithms, e
g ,
the multiple scattering Monte Carlo mathematics found in Modeling and
Characterization of Ultraviolet Scattering Communication Channels. See also
the
MontCarl scattering program cited previously. In UVC NLOS, as cited earlier, a
transmitter sends UVC rays at certain angles through a scattering media (e.g.,
fog),
and the receiver monitors a certain range of angles outside of the line of
sight
direction with the transmitter. The rays from the transmitter will be
redirected by one
or more scattering particles, with some amount of transmitted energy finding
the
receiver. The parameters that affect the amount of power received include the
transmit
ray angles, the receiver's field of view, and the scattering and absorbing
properties of
the thickness of the intervening media. The Monte Carlo mathematical modeling
is
based on the probabilities of rays from the transmitter finding the receiver's
field of
view. The media is modeled using extinction coefficient comprising absorption
and
scattering losses. Now while the NLOS data in the citation is based on
datalink-type
distances of 10 meters or more, the instant application of UVC disinfection
would
generally be less than 30cm (0.3 meters). Over such distances, UVC absorption
losses
in air, water, and UV-grade quartz are used for the simulations. Note that air
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absorbance is negligible, and water greatly depends on its purity, where
ultrapure
water absorbance is also negligible. Scattering losses (rays never reaching a
target) of
course, will be a function of the geometry between source and target and
scattering
particle size(s)/density. Note that for UVC disinfection, the scattering
losses can be
minimized by using a collimated source and illuminating an array of closely-
packed
targets.
1005831 Functional elements of the block diagram ¨ the block diagram in Figure
31 only cites the major functional elements necessary for operation. Note that
some
input parameters may be inferred from other parameters, thereby removing the
need
for one or more inputs. Similarly, some output peripherals may be unnecessary
given
the effects/capabilities of other peripherals. As is tradition, inputs are
shown on the
left, outputs on the right. However, note that some inputs require outputs for
measurement, e.g., a keyboard matrix is typically scanned using digital
outputs to
activate one row or column at a time that is then measured by digital inputs.
Similarly, some output peripherals employ feedback elements that are not
referenced
on the block diagram, e.g., a platform wheel for a robotic system will
typically use
one or more sensors to determine wheel speed Thus, arrows are not used to
avoid
confusion.
[005841 Inputs to the block diagram:
1005851 Input power ¨ wall plug power (US and/or international power)
1005861 Wave-energy beam source sensor(s) ¨ used to detect intensity of the
beam
source(s) at the output of the platform and/or in the far field. Used also to
measure the
scattering properties (using e.g., on-axis/off-axis techniques described e.g.,
in
Gustav Mie and the fundamental concept of electromagnetic scattering by
particles -
A perspective and Light and Photosynthesis in Aquatic Ecosystems, ISBN 978-0-
521-
15175-7).
1005871 Liquid sensors ¨ the liquid is either the feedstock for aerosols or
the
medium e.g., in water disinfection.
1005881 Temperature e.g., determine its influence on particle size in
aerosols.
1005891 Conductance (electrical) to determine the quality of deionized water
when
used as the source of the aerosol or e.g., if electric fields are used as a
complementary
treatment non-photochemical/photophysical modality with kinetic effects for
water
disinfection.
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1005901 Level (full/empty) to inform the operator if filling is required or
must
cease for aerosols, or if there is water flowing for water disinfection
applications.
1005911 Turbidity "is a measure of the degree to which the water loses its
transparency due to the presence of suspended particulates. The more total
suspended
solids in the water, the murkier it seems and the higher the turbidity.
Turbidity is
considered as a good measure of the quality of water" (Turbidity (Lenntech)).
For
aerosols turbidity can effect particle size, and in both surface and water
disinfection
turbidity adds absorption and therefore affects fluence/dosage.
1005921 Flow rate sensors e.g., for aerosols can help indicate the conversion
rate of
liquid into aerosol and pressure drop sensors can help determine whether there
are
potential clogs in the system. For water disinfection, these sensors provide a
necessary input to determine dosage. Scatterer sensors ¨ concentration is a
key
parameter for estimating scattering, and multiple measurements of
concentration can
be used to determine the uniformity of the scattering field.
1005931 Velocity measures the speed and direction of the scattering field,
whether
due to the influence of gravity/buoyancy or added scatterer movers. All of
these
sensors can be measured in the near field where they are generated and the far
field
adjacent the target(s).
1005941 Flow rate and pressure drop e.g., assist in the control of
pressurizer(s) that
are used to force aerosols into surface depressions. Note scatterers include
air bubbles
in water, water droplets in air, powders in air/water/oil, etc.
1005951 Ambient medium sensors ¨ temperature and humidity to determine the
effects e.g., on an aerosol scattering field; motion detector(s) can be
deployed as a
safety to stop operation if a person/animal is detected in the irradiation
zone; imaging
camera(s) e.g., to detect targets and obstacles or in support of
characterizing the
scattering field, ambient illumination e.g., if illuminating foliage in the
dark as cited
e.g., in A shot in the dark _ Good Fruit Grower.
[00596] Velocity is especially important in outdoor applications like on
vineyards
(i.e., wind speed) and can be measured in the near field and at different
locations
between the near field and the target. This will assist in control of the
aerosol movers,
e.g., measured before aerosolization.
1005971 Contact sensors ¨ the flood/Target to determine e.g., if a surface
disinfection platform's hood (if used) has contacted the target if required as
an
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interlock, and Platform/Obstacle for a robotic application that senses
movement
cannot continue along the current path.
1005981 Component parameters ¨ sensors to measure temperature, current,
voltage
as needed to control the light beam source(s) and/or Droplet/bubble
generator(s) at
their highest efficacy and prevent exceeding their targeted values. Also used
during
self-test and factory-testing of circuit and component compliance with
requirements.
[00599] User interface ¨ keyboard for inputting information, controls for
manual
operation ( e.g., joystick for positioning effectors), and an on/off button.
1006001 =Outputs on the block diagram:
[006011 Wave-energy beam source(s) ¨ the target illuminators are those that
effect
change e.g., UVC, Ebeam and/or cavitation source (ultrasonic and/or
hydrodynamic)
for disinfection applications, blue and red light for horticulture
applications, the
visible proxies for scattering feedback ( e.g., visible light with about the
same beam
profile using visible light sensors that may be more cost effective than e.g.,
UVC
sensors). The laser pointer(s) is/are also a type of visible proxy ( e.g.,
405nm violet
from Arbor Scientific, Ann Arbor, MT), but due to its collimation it can
provide
feedback of the general direction of the irradiation Note that the scattering
of the
target field is also characterized before injecting the scatterers in order to
help
characterize the scattering effect within the medium. Note also that the
symbol on the
block diagram is shown as a LED or laser diode, but it is meant to represent
any
applicable light source, e.g., including LPHO mercury and excimer lamps.
1006021 Scatterer generator(s) ¨ the device(s) that convert either the liquid
into
aerosol ( e.g., surface disinfection), inject bubbles into the liquid ( e.g.,
water
disinfection), or disperse powders. Note that the symbol on the block diagram
is
shown as an ultrasonic generator, but it is meant to represent any applicable
scatterer
generator technology ( e.g., one or more pumps for a jet nebulizer).
1006031 Actuators ¨ mechanical movers as required e.g., to change the beam
direction and divergence, open and close valves for aerosols and liquids,
provide
platform locomotion via wheels for a robotic application, and pan/tip/tilt
motion for
distance detectors and/or imaging cameras.
1006041 Scatterer movers ¨devices to mix, shape, direct and/or pressurize the
scatterers ( e.g., the latter to push scatterers through an N95 mask).
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1006051 Subsystem power-- provide input power to a subsystem, e.g., a complete
LIDAR device Target movers ¨ blowers and effectors to move targets, e.g., to
better
illuminate surfaces in shadow like leaves on a grapevine or a fold in an N95
mask.
[00606] User interface ¨ LCDs for complex information conveyance, and
indicators for simple information like power availability, and caution/warning
signaling.
[00607] Distance detection ¨ determination of the objects/walls surrounding
the
platform to better control the illumination. Also enabling for robotic
movement.
[00608] Comm links ¨ wireless and wired links as needed to communicate within
the platform ( e.g., to a LIDAR subsystem such as the Intel RealSenseTM LiDAR
Camera L515. See the Intel RealSense LiDAR L515 Datasheet Rev003, Intel,
Santa Clara, CA). and to agents outside of the platform such as technicians,
cloud
services, etc.
1006091 The platform electronics includes the following main functional items
(see
the 'Systems design and product development section' for sources of supply):
[00610] Microprocessors/controllers ¨ one or more pPs/microcontrollers/FPGAs
to
coordinate platform activity. It is contemplated that for complex systems, a
combination of intercommunicating pPs and microcontrollers will be needed,
whereas
for simple systems a single microcontroller is anticipated.
1006111 Comm links ¨ wired ( e.g., RS-485, USB, ethernet, etc. to connect to
the
Carel systems, as well as other subsystems or a technician's console) and
wireless (
e.g., Bluetooth, Wi-Fi, etc. for connection to a technician's mobile device,
an onsite
server to coordinate activities of multiple platforms, the cloud for telemetry
and/or
control, etc.)
[00612] Timers and Real Time Clocks (RTCs) ¨ typically found within pPs and
microcontrollers, although may be external devices such as watchdog timers
that are
used in real time systems to ensure the system services tasks at the
appropriate time
and interrupt the system if it does not.
1006131 Pulse Width Modulators (PWMs) ¨ also found within microcontrollers,
useful for varying power levels to certain components, e.g., LED drivers.
[00614] Driver amplifiers ¨ devices sourcing higher power than available from
the
small signal output of an analog or digital device. In many instances, these
devices are
specifically engineered to meet the unique voltage/current requirements of a
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peripheral and may include feedback and control loops, e.g., LED drivers, LPHO
mercury lamp drivers, excimer deep UV lamp drivers, ultrasonic atomizer
drivers,
motor drivers, valve solenoid drivers, etc.
[00615] Sensor amplifiers ¨ circuitry for conditioning/filtering the signal
from a
sensor and add gain to maximize S/N based on the full scale input voltage of
the AID.
1006161 A/D ¨ analog to digital converters, often found in microcontrollers,
of
sufficient resolution to meet the system requirements.
[00617] D/A ¨ digital to analog converters, often found in microcontrollers,
of
sufficient resolution to meet the system requirements.
[00618] Power Supply ¨ filters input wall/battery power (and provides energy
storage for short-term demands) and converts to the DC and AC voltages
required by
the platform components. Also used to create subsystem power feeds, if needed.
[00619] Battery ¨ generally rechargeable ( e.g., lithium ion) to provide
sufficient
energy storage for operation of one or more components over a prescribed
period of
time. For simple portable devices, the battery can provide all necessary power
for the
platform for a period of time before requiring recharging. A recharging system
is also
required and may be integrated within the power supply or provided, e.g., via
a wall
charger.
[00620] =Note that most electronic, electromechanical and electrooptical
components are available from one or more of Digi-Key Electronics (Thief River
Falls, MN), Mouser Electronics (Mansfield, TX), and Arrow Electronics
(Centennial,
CO). Liquid and aerosol handling devices are generally recommended by the
atomizer
manufacturer or provided in consultation with their applications engineers.
[00621] This exemplary Block Diagram of Figure 31 serves also as a template
for
other applications and sources of EM/EL/QP wave energy.
[00622] Control systems are also referenced in Feedback Control of Dynamic
Systems (ISBN 978-0-13-349659-8), Sealpump Spray Technology for the Food &
Bakery Industries (brochure, Carel humi Sonic Compact Manual. Many other
examples can be found in the provisional filings.
[00623] Overall Construction ¨ As an exemplary application, the overall
construction can be modeled e.g., after portable foggers. See e.g., US9414580
Heatless and cordless fogging/misting apparatus having a low CFM DC-powered
blower motor and a mixing chamber for ultra-low volume atomized fog,
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US20190154406 Cold fogger, and US9061325 Automatic portable fluid dispersal
device US10322424 Electrostatic fluid delivery backpack system. These
references
show motors, blowers, case construction, battery systems, etc. Due to the
irradiation
involved, care must be taken when selecting materials vis-a-vis
compatibility/degradation.
1006241 Applications (generically) - Note that applications span kinetic
processes
within/upon organisms and their parts (e.g., bacteria, viruses, fungi, and
other
microorganisms, whole plants, leaves, roots, flowers, fruits, even certain
animals,
etc.) and inanimate objects (e.g., chemical toxins, adhesives, etc.). Note
that the term
'organism' will be used as defined in Organism ¨ Wikipedia, "any organic
living
system that functions as an individual entity" where "Organisms are classified
by
taxonomy into groups such as multicellular animals, plants, and fungi; or
unicellular
microorganisms such as protists, bacteria, and archaea." Improvements to the
kinetic
process may be the enhanced reduction in microorganisms on a surface portion
of an
object, the enhanced growth of a plant, enhanced material properties under e-
beam
irradiation, enhanced curing of a photopolymer-based 3D printed object, etc.
1006251 Bubbles in liquids - Bubbles can be generated in water in a number of
ways, the most common being boiling, cavitation, and aeration. "Vaporous
cavitation
is an ebullition process that takes place if the bubble grows explosively in
an
unbounded manner as liquid rapidly changes into vapor. This situation occurs
when
the pressure level goes below the vapor pressure of the liquid. Gaseous
cavitation is a
diffusion process that occurs whenever the pressure falls below the saturation
pressure
of the noncondensable gas dissolved in the liquid. While vaporous cavitation
is
extremely rapid, occurring in microseconds, gaseous cavitation is much slower;
the
time it takes depends upon the degree of convection (fluid circulation)
present.
Cavitation wear occurs only under vaporous cavitation conditions - where the
shock
waves and microjets can erode the surfaces. Gaseous cavitation does not cause
surface
material to erode. It only creates noise, generates high (even molecular level
cracking)
temperatures and degrades the chemical composition of the fluid through
oxidation.
Cavitation wear is also known as cavitation erosion, vaporous cavitation,
cavitation
pitting, cavitation fatigue, liquid impact erosion and wire-drawing."
(Cavitation
Explained and Illustrated).
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1006261 The generation of micron and submicron diameter bubbles can occur via
both cavitation and aeration. Cavitation introduces both benefits (advanced
oxidation)
and risks (erosion), depending upon the needs of a given application. Aeration
has
certain benefits as well "Nanobubbles are often defined as bubbles less than
200 nm
in diameter. At this size, bubbles behave very differently than larger bubbles
because
they don't rise to the surface and burst. Rather, they remain in suspension
and
disperse, elevating oxygen levels throughout the waterbody. Nanobubbles also
provide a mild-oxidant effect that has been shown to destroy algae cells and
reduce
algae toxin levels. These unique properties provide effective, chemical-free
treatment
for algae mitigation." (Xcaret Case Study web (Moleaer))
1006271 "Moleaer's gas-injection technology produces trillions of neutrally
buoyant, negatively charged nanobubbles approximately 100nm in diameter. At
that
size, bubbles stay suspended in water for long periods of time, efficiently
mixing
throughout the entire water column. This enables the nanobubbles to transfer
oxygen
with greater than 90% efficiency while also increasing the oxidation reduction
potential (ORP). The nanobubbles effectively oxygenate the entire body of
water in
warm temperatures independent of depth, providing a distinct advantage over
other
aeration methods." (AWASA Case Study (Moleaer))
1006281 The advanced oxidation effects of aeration appears to be much less
than
via cavitation "The current study demonstrated free-radical generation from
the
collapse of microbubbles in the absence of a dynamic stimulus, such as
ultrasound or
large pressure differentials. The shrinking rate of the collapsing
microbubbles was
extremely slow compared with that of ultrasound-induced cavitation bubbles:
the
microbubbles collapsed completely over a time course of tens of seconds,
whereas the
cavitation bubbles collapsed within microseconds. The result of test 3
indicates that
PFOS was not decomposed by the collapse of microbubbles, suggesting that
neither
pump movement nor microbubble collapse leads to substantial increases in
temperature. Further, the shrinking speed of the collapsing microbubble is not
sufficiently rapid to generate an adiabatic compression. It was therefore
unlikely that
the mechanism of free-radical generation by microbubbles was similar to that
in
cavitation bubbles - the latter being related to the extremely high
temperatures caused
by adiabatic compression during violent collapse. It is generally accepted
that radical
generation requires extreme conditions, such as high temperature. Here we
offer an
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alternate theory, based on the accumulation of ions, to explain radical
generation from
collapsing microbubbles." (Free-Radical Generation from Collapsing
Microbubbles in
the Absence of a Dynamic Stimulus, 2007)
[00629] Also as cited previously, aeration can be introduced in a liquid to
affect
cavitation. Aeration can form macro-, micro-, and nano-bubbles, with bubble
diameters ranging from millimeters to nanometers, respectively. Thus, like
fine water
bubbles in air (e.g., fog), there exists the opportunity to scatter energy
waves using
fine air/gas/vapor bubbles in liquids.
[00630] Exemplary applications would be for cleaning the interior of pipes and
vessels. In one exemplary configuration, the cleaning is performed without
having to
drain the pipe/vessel. For example, a plumber's snake-like device can be
inserted into
a system with a directional nozzle that forces bubbles onto the inner surfaces
of a pipe
or vessel in combination with UVC. Such a system would be useful e.g., to
disinfect
Dental Unit Water Lines (DUWLs). See e.g., Bacterial adhesion and biofilms on
surfaces Influence of material and tube size on DUWLs contamination in a pilot
plant.
[00631] Ideally a system is configured with a permanent fitting in place of a
cleanout plug so that a system need not be drained during cleaning. Such a
fitting
could be as simple as a gate or ball valve that is normally closed, and then
opened for
passage of the inventive system during cleanouts. Before opening the gate, the
system
attaches to a threaded section connected to the gate, where the fluid is
prevented from
spilling out of the pipe or vessel. The system retains the backflow of
pressurized fluid
within which the snake is retained. Once the snake is retrieved, the valve is
closed,
and the system is disconnected from the threaded section. A system for
allowing
cables to snake through pressurized pipes is taught in US6736156 Method and
system
for installing cable in pressurized pipelines.
[00632] At the end of the snake, micron-sized bubbles would be discharged
while a
UVC source irradiated the pipe/vessel. Since bubbles rise against gravity, a
nozzle is
required to jet the bubbles against all interior surfaces, however "Bubbles
less than 1
gm diameter rise so slowly that the rate is not determinable. This is due to
their
random Brownian motion and their low buoyancy" (Nanobubbles (ultrafine
bubbles))
"Submicron size bubbles or nanobubbles are gas bubbles of several hundred
nanometers in diameter [14,18,23-26], usually a mixture of water vapor and
naturally
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or intentionally dissolved gases [23,27]. It has been reported that such
bubbles have a
negligible buoyancy and would remain suspended in solutions for a considerably
long
period of time [14,18,24,25,28-30]. Najall et al. [14] were able to generate
nanobubbles which remained stable for several minutes, while Ushikubo et al.
[31]
reported that submicron size air bubbles and oxygen bubbles could be made
stable for
1 h to 15 days. Zhang et al. [30] produced nano carbon dioxide bubbles and air
bubbles which lasted for several hours and days, respectively. Other studies
also
showed bubbles stable in aqueous solutions for up to a few months [24]."
(Generation
and characterization of submicron size bubbles)
1006331 In another exemplary configuration, the pipe/vessel is depressurized
and
drained, and there may or may-not be some residual liquid along the bottom
that does
not drain. For fully drained systems, a low pressure fog can be used with a
nozzle that
directs the fog against all surfaces. If locations do not fully drain, a low
pressure fog
approach may not be able to penetrate the residual wetted surfaces. In such
cases the
inventive fogging system can be used by pressuring the fog (or other gas or
liquid) to
push-away any residual fluids, at least for a time sufficient to perform the
cleaning
operation An alternative would be to use what is called a pipeline pigging
system,
wherein UVC and bubbling nozzles are arranged around the outer circumference
of
the pig.
1006341 Pigging systems with electrical cables are taught in US8813770 Pig
assembly and method for maintaining a functional line for conveying fluid,
US8805579 Submersible robotically onerable vehicle system for infrastructure
maintenance and inspection. Pigging and cable-pulling systems with batteries
are
taught in US7360752 Apparatus and method for installing lines in conduits,
US10567090 Use of high speed radio frequency protocols for communication with
pipeline pigs and inspection tools. UVC disinfection systems for use within a
pipes
and vessels are taught in W02019178624A1 Device for disinfecting pipelines,
containers and structures (comprising a fogging feature in addition to IN),
U59044521 UV sterilization of containers (citing UV scattering due to water
droplets).
1006351 Application - photobioreactors - By introducing bubbles of the
appropriate
diameter, more even illumination conditions can be created, especially for the
initial
growth phase of photosynthetic eulcaryotic organisms like algae. Algae
themselves
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scatterlight, and so as the concentration increases, their own contribution to
scattering
must be considered. One exemplary approach is to change the bubble sizes as
the
bloom matures, so that the illumination uniformity can always be at the best
possible
level for a given tank geometry. For example, in the beginning, a smaller
bubble size
is used to provide a higher degree of scattering, and as the bloom matures,
larger
bubbles are introduced that have more directional scattering. In order to
optimize the
growth phases, e.g., COMSOL simulations and testing must be used to balance
the
scattering within the tank to achieve the proper illumination conditions. It
may also be
suitable for the organisms to be ported to a different tank geometry (or
features
inserted-into and/or removed-from the existing tank) as their contributions to
scattering increases.
1006361 Application ¨ disinfecting the surfaces of medical devices using UVC *-
bubbles ¨ bubbles and UVC are injected into tubes, lines, drains, catheters,
etc.
006371 Application ¨ submicron bubbles - Below find the non-obvious
observation that "Bubbles less than 1 gm diameter rise so slowly that the rate
is not
determinable. ..." This suggests that such bubbles can conformally coat and/or
surround objects that are in the path of wave energy, maximizing the
scattering into
the shadows on the surfaces of these objects. The same can be said for dry fog
aerosols as they envelop fruits/vegetables, a plastic-wrapped food item,
medical
devices and other objects that cause hospital acquired infections,
restaurant/airplane
tables that may harbor pathogens such as SARS-CoV-2 that could lead to COV1D-
19,
leaves on greenhouse plants to aid in photosynthesis, etc. The enveloping
scattering
field for dry fog (with some analogous effects for bubbles in liquids) is in
part due to
gravity and in part due to aerosol movers (fans), fluid shaping surfaces
(swirl plates,
Cow& effect), ambient air movements (crosswinds), static charges, etc. as
disclosed
herein. Note that applicant's MontCarl simulations show different levels of
germicidal/visible scattering for 1 gm diameter water droplets of various Nd.
This
suggests similar performance of air/gas bubbles in water can be obtained.
1006381 With respect to gaseous bubbles in liquids, an initial bubble radius,
Ro,
tends to increase in size to a final radius, R, and thus the ratio R/Ro is
used in a
number of references. Once achieving the maximum bubble radius, R, the bubble
may
collapse/implode, break-up/split, etc. See e.g., Physics of bubble
oscillations, and
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liandbook of Ultrasonics and Sonochemistry (ISBN 978-981- 287-277-7) Much more
information on bubbles can be found in the provisional filings.
[00639] Below find submicron bubble/droplet information:
[00640] Moleaer's gas-injection technology produces trillions of neutrally
buoyant,
negatively charged nanobubbles approximately 100nm in diameter. At that size,
bubbles stay suspended in water for long periods of time, efficiently mixing
throughout the entire water column. (Moleaer, Carson, CA)
[00641] "Bubbles less than 1 gm diameter rise so slowly that the rate is not
determinable. This is due to their random Brownian motion and their low
buoyancy"
(Nanobubbles (ultrafine bubbles)) "Submicron size bubbles or nanobubbles are
gas
bubbles of several hundred nanometers in diameter [14,18,23-26], usually a
mixture
of water vapor and naturally or intentionally dissolved gases [23,27]."
(Generation
and characterization of submicron size bubbles).
1006421 Below find sources of supply for submicron droplets and bubbles.
1006431 "A Hand-Held Point and Spray Misting Disinfection Unit ... 0.5-3
micron
particle disinfects hard to reach areas" (Products - TOMTTm Environmental
Solutions
SteraMistTm), TOMITm Environmental Solutions, Inc (Frederick, MD)."
iONIZED HYDROGEN PEROXIDE (iHPTM) The atmospheric cold plasma arc
converts the H202 molecules into iHP iHP kills the pathogens achieving high
efficacy and leaves behind only oxygen and humidity in treated spaces." (TOMI
Steramist Binary Ionization Technology (BIT) using Cold Plasma Ionized
Hydrogen
Peroxide (Food Safety Brochure))
[00644] Submicron droplet generators are available from TSI Incorporated
(Shoreview, Minnesota), such as their Constant Output Atomizer, Model 3076,
"The
number median diameter of the droplets the Atomizer generates is about 0.3
micrometer and the geometric standard deviation is less than 2Ø The mean
particle
size of the generated aerosol can be varied between 0.02 and 0.3 micrometer by
atomizing a solution and evaporating the solvent."
[00645] See Table 1 from Aerosol-assisted synthesis of submicron particles at
room temperature using ultra-fine liquid atomization which provides 'Typical
diameters of droplets and particles, and production capacities of some aerosol-
assisted
particle synthesis processes...' and a number of products that generate
submicron
droplets/particles.
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1006461 Dry Vapor System s45 (DVS45) from OMI Industries (Palatine, IL)
'disperses submicron size Fresh Wave IAQ molecules into the air'
1006471 Spray vector products ¨ Vortex Air, from C.C. Steven & Associates
(Ventura, CA). "Sprayvectors are compressed air operated liquid atomizing
devices
capable of producing sub-micron sized spray droplets. Sprayvectors use the
airflow
amplification principle to produce a defined spray pattern. Spray patterns can
be either
widely diffused or directed. The spray characteristics are superior to
conventional
hydraulic nozzles (high pressure liquid forced through a tiny hole), and even
exceed
those of piezoelectric nozzles. Sprayvectors produce very small droplet size
which
results in more surface coverage. As droplet size decreases, the total number
of
droplets increases at a higher rate. The result is that the combined surface
area of
droplets in the spray is increased exponentially. Increased surface contact
provided by
Sprayvectors produce: accelerated liquid-air interaction, more effective
evaporative
cooling, economical use of liquid, controlled, efficient humidification, and
effective
dust control."
1006481 Sub-micron fuel atomizers are discussed in US20040124259 Liquid
atomization system for alitomotive applications
1006491 Micron and submicron droplet generators are available, e.g., from
BUCHI
Corporation (New Castle County, Delaware), such as their Nano Spray Dryer B-90
HP.
1006501 "Submicron size bubbles or nanobubbles are gas bubbles of several
hundred nanometers in diameter [14,18,23-26], usually a mixture of water vapor
and
naturally or intentionally dissolved gases [23,27]. It has been reported that
such
bubbles have a negligible buoyancy and would remain suspended in solutions for
a
considerably long period of time [14,18,24,25,28-30]. Najafi et al. [14] were
able to
generate nanobubbles which remained stable for several minutes, while
Ushilatho et
al. [31] reported that submicron size air bubbles and oxygen bubbles could be
made
stable for 1 h to 15 days. Zhang et al. [30] produced nano carbon dioxide
bubbles and
air bubbles which lasted for several hours and days, respectively. Other
studies also
showed bubbles stable in aqueous solutions for up to a few months [24]."
Generation
and characterization of submicron size bubbles. Nano-bubbles can be created by
high-
energy beams as well as ultrasonic/hydrodynamic cavitation, vaporous/gaseous
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cavitation, sparks, and lasers Note that aerators and multiple hole orifice
plates are
also used for bubble generation.
1006511 Data for larger bubble dynamics can be found in The stability of a
large
gas bubble rising through liquid, Dynamics of an initially spherical bubble
rising in
quiescent liquid, Principles and applications of dissolved air flotation.
1006521 Bubble generation via spargers is cited in The Effects of the
Properties of
Gases on the Design of Bubble Columns Equipped with a Fine Pore Sparger, An
Introduction to Micro Nano-Bubbles and their Applications. Multiple hole
orifice
plates are also used for bubble generation. Spargers are manufactured, e.g.,
by Mott
(Farmington, CT), "spargers introduce gases into liquids through thousands of
tiny
pores, creating bubbles far smaller and more numerous than with drilled pipe"
(per
their website).
1006531 Much like aerosol droplets evaporating, bubbles in water will
collapse, and
this is a key characteristic to the very high pressures in temperatures in
cavitation.
Bubble collapse is discussed in Free-Radical Generation from Collapsing
Microbubbles in the Absence of a Dynamic Stimulus.
1006541 Application ¨ non-HVC F.M. wavelengths + bubbles ¨ References to
information/figures/tables/charts in this section can be found in section
18.13 of the
'071 provisional application. In improved extraction of vegetable oils under
high-
intensity ultrasound and or microwaves, microwave irradiation at 2.45 GHz is
combined with sonication, performed both sequentially (sonication at 19, 25,
40, and
300 kHz) and simultaneously (sonication at 21 kHz). In Microwave energy
potential
for biodiesel production, it cites the industrial use of 915 MHz microwave
power (in
addition to the traditional 2.45 GHz). The chart and table were created to
show the
penetration depths, Dp, (and refractive indices) in air and water vs
frequency, with
lower frequencies having greater Dp for both. As an aside, 410-470 MHz is not
listed
as a restricted band in FCC 47 CFR 15.205 and has greater penetration than
even
915MHz. Data is also shown related to various electromagnetic (EM) frequencies
used to irradiate water for heating (microwave and RF), photocatalysis
(specifically
for TiO2), and germicidal (UVC) applications. These data were input to
MiePlot, and
the approximate bubble diameters required to scatter incident EM waves between
about 15 and 20 (at the intensity level of 10% of maximum). Exemplary
MiePlot
(single bubble scattering) outputs are, respectively: 915 MHz with 100 mm air
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bubbles, where the scattering angle at the intensity down lie from its maximum
¨ 70
,
915 MHz with 10 mm bubbles, where the 1/e intensity is 550, and 915 MHz with 1
mm bubbles, where the 1/e intensity is never reached, dipping to ¨50% of
maximum
intensity at 900. A summary table is also provided. From the table, 25-100mm
bubble radii are needed for highly forward scattering single-bubble scattering
in the
cited RF/microwave region. Bubbles this size are larger than what is shown for
generation via ultrasound cavitation, although such bubble sizes can be
generated in
water via other means (The stability of a large gas bubble rising through
liquid). Also
note that large bubbles also deform from spherical in shape (Dynamics of an
initially.
spherical bubble rising in quiescent liquid), which of course leads to a
different
scattering profile than spherical bubbles (Light Scattering by Nonspherical
Particles,
ISBN 0-12-498660-9). Note that ¨ 400nm radii is needed for highly forward
scattering in the UVA¨UVC region and can be generated via ultrasound.
1006551 It is important to note that the MiePlot charts at 915 MHz show
anisotropic
scattering for bubble radii of lmm and lOmm, although there is noticeable
backscatter, however there may be applications where this is suitable. Data is
provided showing the penetration depth in air (at relative humidities of 0%
and 99%,
respectively) and water covering the UV spectrum. Note that the data appears
to
assume ¨ pure media. In the water treatment industry, UV transmittance (U'VT)
at
254nm (UVT254) is the metric used.
1006561 A cavitation bubble radii plot is shown in SONOSYS Image
brochure english 2015, identifying bubble radii down below lOnm. Note that the
plot
shows that bubble radii are, in a general sense inversely proportional to
frequency, but
are also affected by the intensity of the sonification. EM wavelengths at lOnm
transition from EUV to X-rays. Thus, low energy 'soft' X-ray scattering is
also
feasible (10nm equates to ¨ 123eV). Scattering calculations (e.g., MiePlot)
requires as
an input the refractive index of both air and water. The trend of refractive
indices
versus EM wavelength is shown, as well as the description for soft x-rays.
References
are also provided for the refractive index water below 100nm. MiePlot charts
are also
shown for a lOnm air bubble in water, irradiated at lOnm, with the first using
the
refractive index of 0.988 and a second 9.3% lower than the 0.988 from above,
or .904.
The shape of the curves is about the same, although the peaks are slightly
different.
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[00657] From the above, it can be seen that directional EM scattering in
ultrasonic
cavitation applications covers the range of wavelengths from low energy X-rays
to
UV, Visible, Infrared, and RF into the microwave region. As cited herein,
ultrasonic
cavitation has been previously combined with other modalities with kinetic
effects.
Generally, there are optimum ultrasonic cavitation frequencies for a given
application.
[00658] Process Intensification can be found where synergies can be generated
by
the combination of an efficient cavitation conversion process and the
simultaneous
use the bubbles for efficiently scattering irradiation of a secondary process.
As shown
in the above referenced chart, the bubble radii can be altered by frequency
and
intensity.
[00659] In one exemplary configuration, cavitation is used in a sonochemical
process, wherein the cavitation bubbles are also used by an RF/microwave beam
to
uniformly elevate the temperature of the reactants to accelerate the reaction
rate.
[00660] In another exemplary configuration, cavitation is used to generate
hydrogen and hydroxyls within a contaminated water source, wherein the
cavitation
bubbles are also used to uniformly irradiate the contaminated water source
with UVC.
[00661] Additional bubbles (of the same and/or different size
than the cavitation
bubbles) can be added, e.g., via aeration, to further enhance the uniformity
of
radiation.
[00662] Another exemplary approach would be the use of hydrodynamic cavitation
orifices distributed across the face(s) of a mixing wheel paddle (constructed
of
sufficiently hardened material to minimize cavitation erosion) in order to
distribute
the cavitation bubbles throughout the volume of a vessel, while simultaneously
irradiating the bubble field with a secondary EL, EM, and/or QP source of
irradiation.
One secondary irradiation geometry would be positioned across the face of the
top
and/or bottom of the vessel. Another would be positioned along the central
axis
radiating outward and/or around the circumferential surface of the vessel
irradiating
inward towards the central axis. Irradiators can also be placed adjacent to
the orifices
on the paddle(s).
[00663] Application - light (e.g., UV-B, UV-C, and red light) for plant
pathogen
(e.g., fungus and mites) suppression and an advantage to its application in
the dark ¨
In addition to UVC, visible light and UVB can be used to aid in plant health,
whether
by reducing fungi or mites, where the latter are known to reside on the
underside of
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leaves since these surfaces tend to be shielded from UV. The use of the
inventive
scattering particles improves the coverage of leaf surfaces vs what is
traditionally
available via direct illumination. As cited herein, recent research has shown
that there
is a benefit to disinfecting plants at night.
1006641 Application - improving the efficacy of irradiation in dental
applications
Exemplary applications would be the use of light to cure adhesives and whiten
teeth
in dentistry. "Restoration characteristics are factors that can affect light-
curing a
composite resin - Patient access (mouth opening) can limit light guide
positioning.
The size and angulation of some light guides may make proper surface
positioning
and orientation in the posterior areas impossible. Increased curing times may
be
necessary. Access limitation can result in sub-optimally light tip
orientation, resulting
in light reflection, refraction and shadowing issues." (Successful Light
Curing - Not
As Easy As It Looks - Oral Health Group)
1006651 "Physics of light curing - LED curing lights have been a positive
development for photopolymerization of composites. Considerations to light
cure
composites must include: knowing the disaggregated irradiance¨light spectrum
values
of the curing light; the light spectrum of the IRD(s); and how the distance,
angulation, diameter, and use of barriers of the light guide tip impact on
polymerization of the restorative. Most adhesives and composites are cured in
the
spectrum of 450 nm to 480 nm, but some have photoinitiators below 420 nm;
clinicians should ask the manufacturer about which photoinitiator(s) are being
used. Ii
It would be useful to know the disaggregated irradiance values (knowing the
specific
wavelengths in the ranges of 380 nm to 540 nm).12 Understanding that
irradiance
multiplied by the duration of light curing equals total energy in joules/cm2
that a
composite would need for curing provides information on what additional light-
curing
energy (increased times for curing) is necessary for very light shades
(bleaching
shades), very dark shades of composite resin, flowable composite resin, and
microfill
composite resins.13,14 Light guide tip placement, stabilization, and
orientation are
very important when light curing restorative materials. While many
preparations
provide for excellent clinical access for curing lights, hard-to-reach areas
of the oral
cavity can compromise the energy delivered.15,16" (The Physics of Light Curing
and
its Clinical implications Compendium) . The kinetic process for such curing is
called photocuring or photopolymerization.
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1006661 To aid in light curing, water vapor (have scattering particles
suitable in
size for the close-in curing at the wavelengths of 420nm 480nm as cited above)
can
be used in the oral cavity to minimize shadowing issues. Note that the water
vapor can
be generated by the appropriate nozzle and/or nebulizer attachment that is
connected
to the dental unit water line (DUWL). A combination light and aerosol delivery
device for a dental application is US8485818 Fluid controller. For the instant
application, a 420nm ¨ 480nm light source would be substituted for the laser
in the
'818. Exemplary beam forming optic are taught in US7410283 Dental light guide
and
US9662191 Dental light curing device.
1006671 Similarly, the use of light scattering in the instant invention can
also be
used to improve the illumination in a tooth whitening device. "Devices for use
in
light/heat-activated tooth whitening procedures include the commercially
available
Union Broach Illuminator System, from Union Broach, a Health\Chem Company,
New York, N.Y. This device, as described by the manufacturer, provides direct,
full
spectrum illumination to all of the teeth found in the front of the average
adult's
mouth. However, this device does not uniformly illuminate all sixteen central
teeth in
the front upper and lower arches because of the curvature of the dentition
This
potentially gives rise to uneven results. In addition, the Union Broach device
generates a great deal of heat which is both uncomfortable for the patient and
potentially damaging to the teeth." (US7572124 Apparatus for simultaneous
illumination of teeth). See also US8562955 Light-activated tooth whitening
method
and US10046173 Tooth-whitening device. Further information on tooth whitening
can be found in Tooth whitening techniques (ISBN 978- 1-84214-530-2) and Tooth
Whitening An Evidence-Based Perspective (ISBN 978-3-319-38847- 2).
1006681 For examples of DUWLs and attachments, see e.g., Johnson-Promident
complete catalog 2016.
1006691 Application - bubbles + photocatalytic conversion in liquids -
Photocatalytic conversion, such as UV-B irradiating TiO2, has been shown to be
of
use in remediation applications (see Background for more information).
However, it is
well known that it is a process that requires large surface to volume ratios
since the
reaction rate is proportional to the irradiated surface area of the catalyst.
The two
basic categories of photocatalytic reactors are suspensions of photocatalysts
(slurries
of photocatalyst particles) and immobilized photocatalysts (photocatalysts
coated on a
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stationary surface). Foundational information on photocatalytic conversion can
be
found in Photocatalysis and Water Purification (ISBN 978-3-527-33187-1) and
Photocatalysis - Fundamentals, Materials and Applications (ISBN 978-981-13-
2112-
2).
1006701 A Review of Physiochemical and Photocatalytic Properties of Metal
Oxides Against Escherichia Coli cites the use of nanobubbles in photocatalysis
and
aid in damaging microorganisms. Such a process can be optimized using
computational fluid dynamics (CFD) as taught in Development Of A CFD-Based
Model For The Simulation Of Immobilized Photocatalytic Reactors For Water
Treatment, also citing other photocatalytic CFO analyses, including
Computational
fluid dynamic (CFD) simulation of a pilot-scale annular bubble column
photocatalytic
reactor.
1006711 Application - photocatalysts employing bubbles - The examples in the
instant invention below will also cite aeration as source of bubbles, but any
suitably
sized bubbles generated from the examples and references cited herein
(cavitation,
boiling, etc.) would be applicable. Of course, if using imploding bubbles,
like those
generated by cavitation, one must consider the effects of erosion and also any
sonochemical reactions competing with the photocatalytic reactions.
[006721 Bubble sizes, whether air bubbles in water or water vapor in air, must
be
optimized for both the UV scattering effects and the fluid flow
characteristics adjacent
to the photocatalyst. Again, see the CFD references above and the scattering
simulation tools cited herein.
[00673] Photocatalytic reactors employing bubbles include,
e.g., Modeling and
experimentation of a novel labyrinth bubble photoreactor for degradation of
organic
pollutant.
[00674] In the exemplary configurations below, the photocatalyst is TiO2
(e.g.,
Degussa P25, Evonik Corporation, Parsippany, NJ) with illumination from an
array of
365nm LED light sources, e.g., Luminus P/N SST-10-UV (Luminus, Inc.,
Sunnyvale,
CA). Note that 365nm satisfies the minimum energy for activation of both
anatase
TiO2 (at 384nm, min) and rutile TiO2 (at 411m, min). The maximum wavelength of
the 365nm LED is specified at 370nm, also within the minimum wavelength bounds
for both crystalline phases of P25 TiO2. Shorter wavelengths can be used, but
LED
wall plug efficiency (WPE) tends to be lower for shorter wavelengths. However,
if a
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shorter wavelength length has more output power per LED die without a big hit
to
WPE, then it might be an equitable trade, e.g., to make the system more
compact.
1006751 The vessels cited below can be covered/coated (except for the
apertures for
the illumination, plumbing, sensors, etc.) with material such as aluminum and
PTFE
(and others cited herein) that is highly reflective in the range around 365nm.
This
provides a boost in efficacy by redirecting illumination that would exit the
system
back towards the photocatalysts. Sensors and control systems are constructed
in
accordance with the general teachings cited herein in order to maximize
efficacy, flow
rate, operator safety, etc.
1006761 Application - anti-fouling - "Fouling is the accumulation of unwanted
material on solid surfaces to the detriment of function." (Fouling Versus
Availability,
Fouling - Wikipedia). "A number of factors contribute to fouling and are
strongly
interlinked. Organic, inorganic, particulate, and biological fouling are some
of the
main fouling categories." (Fouling of Nanofiltration Membranes)
1006771 Fouling is a large concern in direct photolysis. See e.g., Fouling Of
UV
Lamp Sleeves - Exploring Inconsistencies In The Role Of Iron. Fouling is also
prevalent in photocatalytic systems. See e g , Fouling and inactivation of
titanium
dioxide-based photocatalytic systems Fouling can also be found in bioreactors.
See
e.g., Fundamentals of Membrane Bioreactors Materials, Systems and Membrane
Fouling (ISBN 978-981-10-2013-1)
1006781 Fouling can be addressed by pre-treatment (filtration, UVC
irradiation,
zonation, ultrasonic, etc.), and in-situ treatment such as chemical, biologic,
physical
(ultrasonics, mechanical scrubbing, backwashing, high-pressure cleaning jet,
cross-
flow and bubble movement).
1006791 Given the above, in exemplary embodiments cited directly below,
bubbles
are simultaneously used in anti-fouling applications for two separate purposes
¨ one
using gas as the medium, the other using liquid as the medium.
1006801 UV is known to degrade biofilm growth amongst cooling coils where
-Reflective aluminum is sometimes added around such systems to remove shadowed
areas" (Ultraviolet Germicidal Irradiation Handbook UVGI for Air and Surface
Disinfection, ISBN 978-3-642-01998-2). Liquids are also used "In chemical
cleaning
techniques biocides are employed such as chlorine, chlorine dioxide, bromine,
ozone
and surfactants. A more usual practice, however, is by continuous or
intermittent
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"shock" chlorination which kills off the responsible organisms. Other cleaning
techniques that can be effective in controlling biological fouling include
thermal
shock treatment by application of heat or deslugging with steam or hot water,
and
some less well-known techniques like ultraviolet radiation [23]." (Fouling in
Heat
Exchangers). For this first exemplary embodiment, a biocide liquid is sprayed
at the
fouling, while the scattering properties of the spray enables UV to irradiate
cooling
coil surfaces in shadow. Thus, the spray provides a dual purpose.
1006811 Air/gas bubbles are also known to dislodge biofilms: Analysis of
Bacterial
Detachment from Substratum Surfaces by the Passage of Air-Liquid Interfaces.
Also,
UVC and UVB are known to degrade biofilms: Inactivation of Pseudomonas
aeruginosa biofilm after ultraviolet light-emitting diode treatment - a
comparative
study between ultraviolet C and ultraviolet B. Thus, in this second exemplary
embodiment, UVC/UVB can be introduced simultaneously with air/gas bubbles as
an
anti-fouling strategy, with the UVC/UVB also scattered by the bubbles to reach
areas
in shadow.
1006821 Scattering paths and nodes - The paths along which wave energy travel
from the source of irradiation to a targeted surface (portion) in shadow
(those not in
direct line of sight of the source as it is irradiating) includes at least one
scatterer (e.g.,
one water droplet in air or an air bubble in a liquid like water) dispersed in
a medium
(i.e. in air for water vapor or liquid for air bubbles). The path, called
herein a
scattering path, may also comprise what can be considered 'relay' elements
that act to
relay at least a portion of the wave energy between adjacent nodes via such
effects as
e.g., reflection, refraction, diffraction, and the like (which may also
include scattering
effects). These relays may have losses, e.g., due to absorption and scattering
effects,
i.e. some portion of the energy incident at a relay element may not be
transferred to
the next element in the scattering path. The relay node receives wave energy
from a
transmitting node (e.g., a source node or a scattering node), and transfers
some or all
of the received energy to a receiving node (e.g., the target node). Relay
nodes can be
external to the target node, or on-or-in the object of the target node. For
example, a
relay node can be a surface portion of a photosynthetic plant that transfers
wave
energy to a target node ¨ a chlorophyll molecule.
[006831 Due to the statistical cloud-like nature of scattering
particles (e.g., from
tens to thousands of scatterers per mm3) or simply as a result of open spaces,
some
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wave energy may arrive at the target without interacting with relay elements,
while
other wave energy may interact with one or more relay elements (e.g., UV
reflecting
surface portions). Still other wave energy may simply not reach the desired
targeted
surface(s). Some wave energy will arrive at different times due to multipath.
1006841 Each connection along the scattering path is called a node herein (and
each
scattering path can be numbered to distinguish between them, e.g., a first
scattering
path, etc.): a) the source of wave energy radiation establishes the source
node b) a
scattering element in the scattering path, establishes a scattering node
(nodes can be
numbered if multiple scatterers are in the same scattering path, e.g., a first
scattering
node, etc.) c) a surface portion for receiving the irradiation, establishes
the target
node.
1006851 A relay, as cited above, if applicable, establishes a relay node
(again,
numbered as necessary if more than one, e.g., a first relay, etc.).
1006861 One method by which the existence of scattering paths may be validated
is
to run the same test with and without the scattering particles, during which
the
I rradiance is measured at targeted surface (portions) in shadow via the
measurement
devices/techniques described herein These tests should he repeated to gain
statistical
significance (cf. Design and Analysis of Experiments, ISBN 978-3-319-52248-7)
given the statistical cloud-like nature in the generation of scattering
particles, flow
dynamics of the scatterers and any foreign objects and debris (FOD), movement
of
surfaces including targeted surfaces (e.g., leaves blowing in the wind),
background
noise in the detector(s), etc.
1006871 Since some surface (positions) in shadow are within crevices, one can
use
e.g., paper-thin 'UV FASTCHECK STRIPS' from UV Process Supply (Chicago, IL)
to test irradiation dosage in a room (for example). A 'standard' test regime
can also be
constructed with UV radiometers buried within the walls of the test article,
with only
the detector area(s) exposed. Artificial 'crevices' can be constructed of
various
shapes, depths, materials, etc. in order to understand the effects of fluid
dynamics,
object UV reflectance, etc. Holes of different sizes and depths (i.e. aspect
ratios),
different angles relative to the surface normal, different hole-to-hole
spacings,
through-holes vs closed cavities, as well as different shapes (cylindrical,
conical, etc.),
materials (e.g., of different UVC reflectivity), surface roughness, etc. can
be used as
part of a test coupon to objectively compare design variations. Standards are
being
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generated for surface disinfection, see e.g., Workshop on Ultraviolet
Disinfection
Technologies & Healthcare Associated Infections - Defining Standards and
Metrology
Needs (Jan-2020) for a list of stakeholders.
1006881 Such test articles also include one or more wave energy sources (and
source monitors) to ensure consistent geometry between source and targeted
surface
(portions). These test articles can sit on a tabletop, comprise an entire room
or even an
outdoor location. Care must be used to ensure the atmospheric conditions
(temperature, humidity, air currents, etc.) and surface reflectivities are
consistent from
run-to-run, or sufficient runs must be compiled to plot their effects. Also,
scatterers
must be removed before each test to ensure establishing consistent baselines.
1006891 Further, the radii, concentration, and spatial/temporal distribution
of
scattering particles must be consistent from run-to-run, or enough runs in
different
conditions in order to plot their effects and yield a statistically
significant result. This
is especially critical when performing outdoor testing, e.g., in a vineyard
where the
application of scattering UVC is being considered to counter powdery mildew
and so
the effects of random air currents must be understood. Another application
would be a
greenhouse where it is desired to scatter selected wavelengths of visible
light from
LEDs (see products e.g., from Fluence, Austin, TX, an Osram company) to
enhance
photosynthesis by illuminating leaf areas that are in shadow and so the effect
of the
randomness of leaf locations must be understood (also true for the vineyard
application).
1006901 Note that if the end application is UVC, a visible light proxy can be
tested
beforehand to give better access to diagnostics. If this is done, one must
understand
the different in scattering due to the relationship between the size of the
scatterers and
the wavelength as described herein. This, of course, is easily modeled in a
program
like MontCarl. If the size of the scatterers is modified to maintain the same
scattering
profile, then any fluid dynamic effects on particles of a different size must
also be
understood.
1006911 In one embodiment, violet or blue light is used as a proxy in order to
use
the real scatterers while minimizing wavelength effects on scattering for the
embodiment where the end application uses UVC. Of course, the differences in
the
irradiating beam (beam width, angle, uniformity, wavelength spread, etc.)
between the
UVC source and the visible proxy must be minimized as well. In some
embodiments,
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spherical solid particles can be used as a proxy, available e.g., from
Polysciences, Inc.
(Warrington, PA). Particle analyzers are available e.g., from Malvern
Panalytical Ltd
(Malvern, United Kingdom) and CH Technologies (USA), Inc (Westwood, NJ). See
also a very detailed summary of analyzers and analysis techniques in 'Appendix
B:
PDI Supporting Documentation' in Measuring and Modeling Aerosols in Carbon
Dioxide Capture by Aqueous Amines.
1006921 Fluorescent imbued diagnostic materials, called 'markers', are used as
a
visible diagnostic for determining the efficacy of a surface cleaning regime,
see e.g.,
ATP Bioluminescence and Fluorescent Markers. See also Dos and don'ts for
hospital
cleaning, An overview of automated room disinfection systems - When to use
them
and how to choose them. In these applications, clear fluorescent markers are
placed
around a room to evaluate how well surfaces are cleaned with disinfectants by
inspecting after cleaning with a UV light and looking for fluorescence
(indicating
missed spots). For the instant application, fluorescent markers can be used
e.g., to
determine whether surfaces in shadow are irradiated with UV (with and without
scatterers). As an aside, bioluminescence is another diagnostic that is used
and is
discussed e g , in No-Tot tch Automated Disinfection System for
Decontamination of
Surfaces in Hospitals.
[006931 Exemplary fluorescent markers are cited in Ultraviolet Powder versus
Ultraviolet Gel for Assessing Environmental Cleaning, such as the GlitterBug
brand
of UVA fluorescent products from Brevis Corporation (St. Lake City, Utah) and
DAZOO Fluorescent Marking Gel from Ecolab (St. Paul, Minnesota). The
tluorophores (light emitting fluorescent molecules) may be constructed for use
with
UVA excitation "with a range of from 365 to about 395 nm. For example, the UV
light source in the kit can be a 12 LED bulb UV flashlight (e.g., Abco Tech 12
LED
UV 375 nm 3 AAA flashlight), that emits light having a wavelength of 375 nm."
(Ecolab's patent filing US20200085986 Use of fluorescent polymers in marking
compositions for the diagnostic determination of cleaning performance).
Fluorophores
have minimum excitation wavelengths (Fluorescent Probes Thermo Fisher
Scientific ¨ US), suggesting that a U VC source may not effectively illuminate
a
fluorophore designed for use with a UVA source. Such fluorophores, however,
allow
diagnostics of the scattering performance using UVA that is closer to the
desired UVC
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light than blue or violet, thus more closely simulating true system
performance when
using the scatterers planned for the final scattering UVC application.
1006941 Polarization - as mentioned in section 12.9 of the '071, "polarization
in
both air and water is produced by scattering ..." (Patterns and properties of
polarized
light in air and water). "With polarization filters it is possible to separate
diffilse from
specular reflections ... since polarization is changed at each scattering
event."
(Backscattering elimination in fog for advanced driver assistance systems with
LED
matrix headlights). See also Seeing Through Fog - Polarized Light Persistence
in
Scattering Environments (degree of polarization, DOP, was calculated to
compare
linear vs circular polarization as a function of wavelength, optical
thickness, and
particle size distributions, with circular polarization performing for most
visible/IR
wavelengths) and Superior signal persistence of circularly polarized light in
polydisperse, real-world fog environments, having many common authors. See
also
Polarized light propagation through scattering media - time-resolved Monte
Carlo
simulations and experiments, Depolarization of multiply scattered waves by
spherical
diffusers - Influence of the size parameter and Monte-Carlo Simulation of
Light
Scattering in Turbid Media. (Frits F M de Mul, author of MontCarl cited
herein). A
very quick way to see the differences in polarization through single fog
droplets is to
use the MiePlot app, define the wavelength and droplet size, and set
'Polarisation' to
'both'. Polarization effects should be measured when using scatterometers with
the
instant invention to ensure accurate inferences. Also note that Fresnel
reflections are
polarization sensitive and thus the absorption of wave energy at a surface
(important
in disinfection) can vary with the polarization state of the beam, which is
dependent
upon the polarization of the source itself, different polarization effects due
to the
interactions with other objects, and due to the scattering fog. For example,
"Brewster's
angle is an angle of incidence at which light with a particular polarization
is perfectly
transmitted through a transparent dielectric surface, with no reflection. When
unpolarized light is incident at this angle, the light that is reflected from
the surface is
therefore perfectly polarized" (from the Wikipedia for Brewster's angle). For
rough
surfaces see, e.g., Light scattering from a random rough interface with total
internal
reflection. For general information on polarization transmittance and
reflections under
various conditions for different materials, see, e.g., Optics (Fifth Edition,
Hecht, ISBN
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978-1-292-09693-3), which stated in part "linear light reflected from a metal
surfaced
mirror will have phase shifts introduced that cause it to emerge as elliptical
light."
1006951 Polarization is also affected by the shape and alignment of the
scatterers.
See, e.g., Particle shape determination from polarization fluctuations of
scattered
radiation (citing scatterers that are prolate or shaped like a rugby ball,
spherical, and
oblate shaped like a flattened pumpkin). This should be considered when
working
with non-spherical scatterers as well as when disinfecting powders and the
like, which
may exhibit some degree of polarization anisotropy. Particle alignment is also
to be
considered: "We present radiative transfer calculations showing the
polarization
effects of scattering and absorption by aligned grains. The grain model
consists of a
size distribution of oblate or spinning prolate particles with varying degrees
of
alignment. To develop an understanding of the radiative transfer effects, we
begin
with the simple case of a spherical envelope illuminated by a central source
with
constant grain alignment axis throughout the envelope. Nonaligned grains
produce no
net polarization in such envelopes, while aligned grains produce substantial
linear and
circular polarization. The linear polarization results from the competing
effects of
differential extinction and scattering The polarization varies strongly with
optical
depth, with scattering dominating at low optical depth and differential
extinction
dominating at high optical depth." Scattering And Absorption By Aligned Grains
In
Circumstellar Environments.
1006961 LISTING OF REFERENCE NUMERALS IN FIGURES
Figure 1
100 - UV Tunnel system (Here strawberries ride along a conveyor belt inside
a 'UV tunnel' that contains many UVC lamps illuminating them from above and
below. Dry fog has been injected into the tunnel, and the resultant scattering
illuminates the strawberries from a wider range of angles than if without fog.
This
can be seen by looking at the final angle of the two light rays that strike
the
strawberry on the left. The dashed lines trace back to locations that could
not have
come from a lamp directly, and that is how this technology reaches the
shadows.
Direct rays are available both with and without dry fog.)
110 - UVC tunnel entrance wall
120 - UVC lamp surrounded by aluminum cusp specular reflector covered by
UV quartz glass plate
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130 ¨ Fog Plenum
135 - Fog is directed downward to treatment zone by 1-of-n diffusers and/or
(directional) injectors
140 - Dry Fog
150 - Wire-link conveyor belt allowing UVC to pass through
160 ¨ UVC lamps with reflectors
165 - UVC tunnel exit wall (in some embodiments Strip-type curtains (not
shown) substantially contain the dry fog within the UVC tunnel)
170 - Optional vacuum hood & dryer for removal of residual fog & excess
moisture on exit side
175 - Exemplary UVC rays scattered by dry fog
180 - Fog continues to drop due to gravity and condensate is collected in
drain
at bottom
190 - The final angle of the light ray reaching the strawberry could not have
come from a direct-view ray
195 - Direct Ray
Figure 5
500 - UVC lamps/rays
510 - Microbe
520 - 'canyon walls' of a crack/crevice at some height:vvidth aspect ratio
530 - Direct field of view of the microbe ¨ no lamps in sight
Figure 6
500 - UVC lamps/rays
510- Microbe
520 - 'canyon walls' of a crack/crevice at some height:width aspect ratio
530 - Direct field of view of the microbe no lamps in sight
540 - Expanded field of view with some lamps in sight
550 - Exemplary MontCarl ray trace renderings (05 droplets at Nd=106cm-3,
X=254nm, tFoG=5.85") from this presentation
560 - Fog field
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Figure 7
700 -
710 - Conveyor bell
720 - UV Tunnel
730 - UVC Lamp cassettes
740 - Tunnel Guarding
750 - Box (pushed, e.g., by a U-shaped paddle that is attached to the belt,
will
also prevent box from skewing and jamming travel). Wet/dry washable HEPA
filter
allows air to pass (but not fog) during fog-fill and vacuum exhaust. Optional
desiccant.
760 HEPA
765 - Water
770 - Tables (prevents box & hose from falling to floor, tabletop heights same
as conveyor belt)
775 3-way valve Secured to tabletop
780 - Dry fog generator
785 - Hose (UV resistant) with slack laying flat on smooth-topped table to
minimize the weight of the hose from pulling on the box. Also avoids creating
a water
trap that would block flow. Hose has enough slack for the box to travel from
table to
table. Hose guided, e.g., by U-channels that are zip-tied to the belt to keep
hose from
kinking when pushed & pulled, especially when being pushed through the UV
protection slats at the entrance/exit of the guarding.
790 - Exhaust
Figure 8
800 - Modular Unit for powder treatment with UVC
810 - Every point on the circumference of the UV transmissive inner cylinder
receives scattered rays from the dry fog over a wide range of angles,
effectively
creating a larger diffuse emitter surface that directs UVC into the powder.
Rays that
miss the powder are reflected by the UVC reflector and either strike the
powder on
the return-trip or pass through the powder again and re-scatter in the fog
only to reach
the powder again at another location. The odds of reflected UVC rays getting
re-
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absorbed by the lamp plasma* are lower than if the lamp was closely surrounded
by
the powder.
820 - Powder (e.g., flour) within a gap between a UV transmissive inner
cylinder and an outer cylinder that is either (a) UVC reflective, or (b) a UVC
transmissive cylinder covered in a UVC reflector. Gap size is chosen based on
the
needs of the application, weighting such factors as (a) low pressure drop, (b)
high
dosage uniformity, (c) power efficacy, (d) product throughput, etc. Air flow
of the
appropriate humidity (to prevent clumping) can be introduced to swirl the
flour for
better dosage uniformity, much as is done by swirling water in UVC water
treatment
systems.
830 - Dry fog within a UV transmissive cylinder whose radius is determined
by the distance necessary for efficient UV forward scattering with good UV
homogenization.
840 - UVC LP Lamp
850 - Highly reflective diffuse UVC Reflector
860- Fog in this area
870- Powder in this area
880 - Exemplary UVC rays
Figure 10
1000 - Polypropylene tote (interior size)
1010 - Inner, telescoping 4.3" OD PVC tube, open to the air in the left side
of
tote, which is devoid of fog. Optional black flocking paper liner installed
against
interior surface.
1020 - Outer, fixed 4.6" OD PVC tube fixed/sealed to partition stiffeners to
prevent fog leakage. ID allows slip fit to inner tube.
1030 - Partition - black 3/4" thick foam with 4 mm plastic plate stiffeners
shown on either side, sealed to tote interior walls to prevent fog leakage to
left side of
tote.
1040 - Gap that defines the dry fog thickness
1050 - Square window (sealed to tube)
1060 - 22mm OD fog bulkhead connector on far side of chamber
1070 - Clear window, sealed to tote to prevent fog leakage
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1080 - Sensor paddle/wand, facing spotlight, isolated from the fog within a
transparent PC tube.
1085 - Wide FOV source monitor, facing spotlight
1090 - Polycarbonate (PC) tube suspended by sealed bulkhead connectors
through the sidewalls of the tote (interior of tube is devoid of fog, open to
ambient air
on both ends). Optional shadow-inducing black vinyl tape and magnetic balls
not
shown around the outside of the tube.
1095 - Fog chamber portion (10.25" W into the page)
Figure 15
1500 - Polypropylene tote (interior size)
1510- Inner, telescoping 4.3" OD PVC tube
1520 - Outer, fixed 4.6" OD PVC tube
1530 -Partition
1540 - Gap between window and polycarbonate tube
1550¨ Window
1560 - 22mm OD fog bulkhead connector on far side of chamber
1570 - Black flocking paper on far side of tote, absorbing side facing
spotlight
1575 - White LED spotlight (source), 9.5" from far side of tote facing
paddle/wand
1580 - Active sensor on far side of paddle/wand that is pressed against tote,
facing spotlight.
1585 - Wide FOV source monitor, facing spotlight (same relative position to
spotlight as in other drawing)
1590 - Polycarbonate tube (empty)
1595 Fog chamber portion (right side of partition)
Figure 22
2200 - Polypropylene tote (interior size)
2210 - Inner, telescoping 4.3" OD PVC tube, fully retracted
2220- Outer, fixed 4.6" OD PVC tube
2230 ¨ Partition
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2240 - Top cover
2250 - 22mm OD fog bulkhead connector on far side of chamber
2260 - Fog chamber portion (right side of partition)
2270 - Polycarbonate tube (empty)
2280 - White LED spotlight (source), 9.5" from far side of tote facing
paddle/wand
2290 - Active sensor on far side of paddle/wand that is pressed against tote,
facing spotlight.
2295 - Wide FOV source monitor, facing spotlight (same relative position to
spotlight as in other drawings)
Figure 23
2300 - HomeSoae, cross section (view through door)
2310 - Upper tubular UVC lamp
2320 - Threaded rod inside corresponding threaded holes in 1-2-3 blocks
2330 - UVC reflection from right sidewall (also from inside of door and far
wall, not shown)
2335 - Upper `UV512C' UVC sensor puck facing the PC sidewall sheet,
aligned to the inside surface of the 1-2-3 Block
2340 - Nuts, locking the 1-2-3 blocks to the threaded rod via flat washer (not
shown)
2345 - 1-2-3 Blocks, positioned along right sidewall (partially occluded in
this
view), ¨ 4" from inside face of the front door, with inside face approx. along
centerline of lamps
2350 - Lower 'UV Clean' UVC sensor puck, facing the lower LP UVC lamp,
in clearance hole of PC bottom sheet
2355 - Lower tubular UVC lamp, blocked by PC bottom sheet
2360 - PC bottom sheet, absorbing UVC from upper and lower tubular UVC
lamps
2370 - Dashed circle is the approx. vertical location of the dry fog injection
connector added to the front door
2380 - Dry fog
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2390 - Polycarbonate (PC) sheet (UVC absorbing), blocking left sidewall
reflections, w ¨ 1.2", where (d + 11/16" + h) ===-= 9 1/8")
Figure 26
2600 - Fog field, thickness shortened in order to see scattered rays reach the
detector
2610 - Exemplary MontCarl ray trace rendering (05m droplets at Nd=106cm-3,
1=254nm, tFoG=5.85") from this presentation
2620 - Upper UVC lamp in the HomeSoap unit
2630 - Upper UVC sensor (shown partially transparent to follow the rays),
facing the UVC-absorbing polycarbonate (PC) sheet covering left wall (not
shown)
inside the HomeSoap cavity
2640 - Adjustable height platform inside the HomeSoap cavity supporting
the upper UVC sensor
2650 - To reach the detector, UVC rays emitted from the lamp need to be
offset by some angle, a
1006971 Although the present invention has been described in relation to
particular
embodiments thereof, many other variations and modifications and other uses
will
become apparent to those skilled in the art. It is preferred, therefore, that
the present
invention be limited not by the specific disclosure herein, but only by the
appended
claims.
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