Note: Descriptions are shown in the official language in which they were submitted.
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DISPOSABLE OPHTHALMIC INJECTION DEVICE
10
BACKGROUND OF THE INVENTION
The present invention relates to a single-use medical device and more
particularly to a two-piece ophthalmic drug delivery device with a disposable
tip end
containing an improved plunger linkage and seal.
Several diseases and conditions of the posterior segment of the eye threaten
vision. Age related macular degeneration (ARMD), choroidal neovascularization
(CNV), retinopathies (e.g., diabetic retinopathy, vitreoretinopathy),
retinitis (e.g.,
cytomegalovirus (CMV) retinitis), uveitis, macular edema, glaucoma, and
neuropathies are several examples.
These, and other diseases, can be treated by injecting a drug into the eye.
Such injections are typically manually made using a conventional syringe and
needle.
Figure 1 is a perspective view of a prior art syringe used to inject drugs
into the eye.
In Figure 1, the syringe includes a needle 105, a luer hub 110, a chamber 115,
a
plunger 120, a plunger shaft 125, and a thumb rest 130. As is commonly known,
the
drug to be injected is located in chamber 115. Pushing on the thumb rest 130
causes
the plunger 120 to expel the drug through needle 105.
In using such a syringe, the surgeon is required to puncture the eye tissue
with
the needle, hold the syringe steady, and actuate the syringe plunger (with or
without
the help of a nurse) to inject the fluid into the eye. The volume injected is
typically
not controlled in an accurate manner because the vernier on the syringe is not
precise
relative to the small injection volume. Fluid flow rates are uncontrolled.
Reading the
vernier is also subject to parallax error. Tissue damage may occur due to an
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"unsteady" injection. Reflux of the drug may also occur when the needle is
removed
from the eye.
An effort has been made to control the delivery of small amounts of liquids. A
commercially available fluid dispenser is the ULTRATm positive displacement
dispenser available from EFD Inc. of Providence, Rhode Island. The ULTRA
dispenser is typically used in the dispensing of small volumes of industrial
adhesives.
It utilizes a conventional syringe and a custom dispensing tip. The syringe
plunger is
actuated using an electrical stepper motor and an actuating fluid. Parker
Hannifin
Corporation of Cleveland, Ohio distributes a small volume liquid dispenser for
drug
discovery applications made by Aurora Instruments LLC of San Diego,
California.
The Parker/Aurora dispenser utilizes a piezo-electric dispensing mechanism.
Ypsomed, Inc. of Switzerland produces a line of injection pens and automated
injectors primarily for the self-injection of insulin or hormones by a
patient. This
product line includes simple disposable pens and electronically-controlled
motorized
injectors.
U.S. Patent No. 6,290,690 discloses an ophthalmic system for injecting a
viscous fluid (e.g. silicone oil) into the eye while simultaneously aspirating
a second
viscous fluid (e.g. perflourocarbon liquid) from the eye in a fluid/fluid
exchange
during surgery to repair a retinal detachment or tear. The system includes a
conventional syringe with a plunger. One end of the syringe is fluidly coupled
to a
source of pneumatic pressure that provides a constant pneumatic pressure to
actuate
the plunger. The other end of the syringe is fluidly coupled to an infusion
cannula via
tubing to deliver the viscous fluid to be injected.
It would be desirable to have a portable hand piece for injecting a drug into
the
eye that includes a relatively inexpensive tip segment that can be attached to
and
removed from a reusable assembly. Placing the more expensive components,
including electronics and a drive mechanism, in the reusable assembly, while
keeping
the sterile components in the tip assembly, improves the efficiency and cost-
effectiveness of a drug delivery system. It would be desirable to have a
reusable
assembly that contains the functionally and components for the injection
process. It
would also be desirable to have a disposable tip segment that can be easily
attached to
the reusable assembly for the injection, and then easily removed and discarded
after
the injection. Such a system provides numerous benefits over prior art
injectors.
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SUMMARY OF THE INVENTION
In one embodiment consistent with the principles of the present invention, the
present invention is a disposable injection device having a dispensing chamber
housing, a plunger, a needle, and a temperature control device. The dispensing
chamber housing has an inner surface and an outer surface. The inner surface
partially defines a dispensing chamber for receiving a quantity of a
substance. The
plunger is engaged with the inner surface of the dispensing chamber housing,
is
capable of sliding in the dispensing chamber housing, and is fluidly sealed to
the inner
surface of the dispensing chamber housing. The plunger has a plunger
interface. The
needle is fluidly coupled to the dispensing chamber. The temperature control
device
at least partially surrounds the dispensing chamber housing and alters a
temperature of
the substance in the dispensing chamber. The substance is injected after the
temperature of the substance is altered.
In another embodiment consistent with the principles of the present invention,
the present invention is a disposable injection device having a dispensing
chamber
housing, a plunger, a needle, a temperature control device, a thermal sensor,
a pair of
interface connectors, and a housing. The dispensing chamber housing has an
inner
surface and an outer surface. The inner surface partially defines a dispensing
chamber
for receiving a quantity of a substance. The plunger is engaged with the inner
surface
of the dispensing chamber housing, is capable of sliding in the dispensing
chamber
housing, and is fluidly sealed to the inner surface of the dispensing chamber
housing.
The plunger has a plunger interface. The needle is fluidly coupled to the
dispensing
chamber. The temperature control device at least partially surrounds the
dispensing
chamber housing and alters a temperature of the substance in the dispensing
chamber.
The thermal sensor is located near the dispensing chamber housing and measures
a
temperature near the dispensing chamber housing. The pair of interface
connectors
are located on an interfacing surface of the disposable injection device. The
housing
at least partially encloses the dispensing chamber housing and the plunger.
The
substance is injected after the temperature of the substance is altered.
It is to be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only and are
intended to
provide further explanation of the invention as claimed. The following
description, as
well as the practice of the invention, set forth and suggest additional
advantages and
purposes of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part
of this specification, illustrate several embodiments of the invention and
together with
the description, serve to explain the principles of the invention.
Figure 1 is a perspective view of a prior art syringe.
Figure 2 is one view of an ophthalmic medical device including a disposable
tip segment and a limited reuse assembly according to an embodiment of the
present
invention.
Figure 3 is another embodiment of a limited reuse assembly according to the
principles of the present invention.
Figure 4 is a cross section view of another embodiment of a limited reuse
assembly according to the principles of the present invention.
Figure 5 is a cross section view of a disposable tip segment and a limited
reuse
assembly according to an embodiment of the present invention.
Figure 6 is a cross section view of a disposable tip segment for an ophthalmic
medical device according to an embodiment of the present invention.
Figure 7 is a cross section view of a disposable tip segment for an ophthalmic
medical device according to an embodiment of the present invention.
Figure 8 is a cross section view of a disposable tip segment and a partial
view
of a limited reuse assembly according to an embodiment of the present
invention.
Figure 9A is a cross section view of a disposable tip segment for an
ophthalmic medical device according to an embodiment of the present invention.
Figure 9B is an end view of the embodiment of Figure 9A.
Figures 10A-10D are schematic depictions of four different circuits that may
be included in embodiments of the present invention.
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Figure 11 is end view of a limited reuse assembly according to the principles
of the present invention.
Figure 12 is a cross section view of a limited reuse assembly according to an
embodiment of the present invention.
Figure 13 is a cross section view of a limited reuse assembly according to an
embodiment of the present invention.
Figures 14 and 15 are cross section views of two subassemblies according to
the principles of the present invention.
Figure 16 is a cross section view of a limited reuse assembly, tip segment,
and
a charging base according to the principles of the present invention.
Figures 17A and 17B are flow charts of one method of injecting a substance
into an eye according to the principles of the present invention.
Figure 18 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention.
Figure 19 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention.
Figure 20 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is now made in detail to the exemplary embodiments of the
invention, examples of which are illustrated in the accompanying drawings.
Wherever possible, the same reference numbers are used throughout the drawings
to
refer to the same or like parts.
Figure 2 is one view of an ophthalmic medical device including a disposable
tip segment and a limited reuse assembly according to an embodiment of the
present
invention. In Figure 2, the medical device includes a tip segment 205 and a
limited
reuse assembly 250. The tip segment 205 includes a needle 210, a housing 215,
and
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an optional light 275. The limited reuse assembly 250 includes a housing 255,
a
switch 270, a lock mechanism 265, and a threaded portion 260.
Tip segment 205 is capable of being connected to and removed from limited
reuse assembly 250. In this embodiment, tip segment 205 has a threaded portion
on
an interior surface of housing 215 that screws onto the threaded portion 260
of limited
reuse assembly 250. In addition, lock mechanism 265 secures tip segment 215 to
limited reuse assembly 250. Lock mechanism 265 may be in the form of a button,
a
sliding switch, or a cantilevered mechanism. Other mechanisms for connecting
tip
segment 205 to limited reuse assembly 250, such as those involving structural
features
that mate with each other, are commonly known in the art and are within the
scope of
the present invention.
Needle 210 is adapted to deliver a substance, such as a drug, into an eye.
Needle 210 may be of any commonly known configuration. Preferably, needle 210
is
designed such that its thermal characteristics are conducive to the particular
drug
delivery application. For example, when a heated drug is to be delivered,
needle 210
may be relatively short (several millimeters) in length (for thermal purposes)
to
facilitate proper delivery of the drug.
Switch 270 is adapted to provide an input to the system. For example, switch
270 may be used to activate the system or to turn on a temperature control
device.
Other switches, buttons, or user-directed control inputs are commonly known
and
may be employed with limited reuse assembly 250 and / or tip segment 205.
Optional light 275 is illuminated when tip segment 205 is ready to be used.
Optional light 275 may protrude from housing 215, or it may be contained
within
housing 215, in which case, optional light 275 may be seen through a clear
portion of
housing 215. In other embodiments, optional light 275 may be replaced by an
indicator, such as a liquid crystal display, segmented display, or other
device that
indicates a status or condition of disposable tip segment 205. For example,
optional
light 275 may pulse on and off to indicate other states, such as, but not
limited to a
system error, fully charged battery, insufficiently charged battery or faulty
connection
between the tip segment 205 and limited use assembly 250. While shown on tip
segment 205, optional light 275 or an additional indicator may be located on
limited
reuse assembly 250.
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Figure 3 is another embodiment of a limited reuse assembly according to the
principles of the present invention. Limited reuse assembly 250 includes a
button
308, a display 320, and a housing 330. Disposable tip segment 205 attaches to
end
340 of limited reuse assembly 250. Button 308 is actuated to provide an input
to the
system. As with switch 270, button 308 may activate a temperature control
device or
initiate actuation of a plunger. Display 320 is a liquid crystal display,
segmented
display, or other device that indicates a status or condition of disposable
tip segment
205 or limited reuse assembly 250.
Figure 4 is a cross section view of another embodiment of a limited reuse
assembly according to the principles of the present invention. In Figure 4,
power
source 505, interface 517, actuator 515, and actuator shaft 510 are located in
housing
255. The top part of housing 255 has a threaded portion 260. Lock mechanism
265,
switch 270, button 308, and indicators 306, 307 are all located on housing
255.
Power source 505 is typically a rechargeable battery, such as a lithium ion
battery, although other types of batteries may be employed. In addition, any
other
type of power cell is appropriate for power source 505. Power source 505
provides
power to the system, and more particularly to actuator 515. Power source 505
also
provides power to a tip segment connected to limited reuse assembly 250. In
such a
case, power source 505 may provide power to a temperature control device (not
shown) located in the tip segment. Optionally, power source 505 can be removed
from housing 255 through a door or other similar feature (not shown).
Interface 517 is typically an electrical conductor that allows power to flow
from power source 505 to actuator 515. Other interfaces, like interface 517,
may also
be present to provide power to other parts of the system.
Actuator shaft 510 is connected to and driven by actuator 515. Actuator 515 is
typically a stepper motor or other type of motor that is capable of moving
actuator
shaft 510 precise distances. In one embodiment, actuator shaft 510 is
connected via a
mechanical linkage to a tip segment that delivers a drug into an eye. In such
a case,
actuator 515 is a stepper motor that can precisely move shaft 510 to deliver a
precise
quantity of drug into the eye. Actuator 515 is secured to an interior surface
of
housing 255 by, for example, tabs that engage the outer surface of actuator
515.
In other embodiments, actuator 515 is a linear actuator or linear driver. In
such a case, actuator 515 may be a spring or spring driven mechanism, a geared
DC
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motor with a rotary sensor coupled to a linear drive or a dc motor coupled to
a linear
drive with a linear sensor, or a linear stepper motor. Other types of motors,
like a
rotational permanent magnet motor, may also be used for actuator 515.
Lock mechanism 265, switch 270, and button 308 are all located on housing
255 so that they can be manipulated by hand. Likewise, indicators 306, 307 are
located on housing 255 so that they can be viewed. Lock mechanism 265, switch
270,
button 308, and indicators 306, 307 are also connected to a controller (not
shown) via
interfaces (not shown) located in housing 255.
Figure 5 is a cross section view of a disposable tip segment and a limited
reuse
assembly according to an embodiment of the present invention. Figure 5 shows
how
tip segment 205 interfaces with limited reuse assembly 250. In the embodiment
of
Figure 5, tip segment 205 includes assembly 555, plunger interface 420,
plunger 415,
dispensing chamber housing 425, tip segment housing 215, temperature control
device 450, thermal sensor 460, needle 210, dispensing chamber 405, interface
530,
and tip interface connector 453. Limited reuse assembly 250 includes
mechanical
linkage interface 545, actuator shaft 510, actuator 515, power source 505,
controller
305, limited reuse assembly housing 255, interface 535, and limited reuse
assembly
interface connector 553.
In tip segment 205, plunger interface 420 is located on one end of plunger
415.
The other end of plunger 415 forms one end of dispensing chamber 405. Plunger
415
is adapted to slide within dispensing chamber 405. The outer surface of
plunger 415
is fluidly sealed to the inner surface of dispensing chamber housing 425.
Dispensing
chamber housing 425 surrounds the dispensing chamber 405. Typically,
dispensing
chamber housing 425 has a cylindrical shape. As such, dispensing chamber 405
also
has a cylindrical shape. In tip segment 205, assembly 555 includes any number
of
components as described below.
Needle 210 is fluidly coupled to dispensing chamber 405. In such a case, a
substance contained in dispensing chamber 405 can pass through needle 210 and
into
an eye. Temperature control device 450 at least partially surrounds dispensing
chamber housing 425. In this case, temperature control device 450 is adapted
to heat
and/or cool dispensing chamber housing 425 and any substance contained in
dispensing chamber 405. Interface 530 connects temperature control device 450
with
tip interface connector 453.
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The components of tip segment 205, including dispensing chamber housing
425, temperature control device 450, and plunger 415 are at least partially
enclosed by
tip segment housing 215. In one embodiment consistent with the principles of
the
present invention, plunger 415 is sealed to the interior surface of dispensing
chamber
housing 425. This seal prevents contamination of any substance contained in
dispensing chamber 405. For medical purposes, such a seal is desirable. This
seal
can be located at any point on plunger 415 or dispensing chamber housing 425.
In limited reuse assembly 250, power source 505 provides power to actuator
515. An interface (not shown) between power source 505 and actuator 515 serves
as
a conduit for providing power to actuator 515. Actuator 515 is connected to
actuator
shaft 510. When actuator 515 is a stepper motor, actuator shaft 510 is
integral with
actuator 515. Mechanical linkage interface 545 is connected to actuator shaft
510. In
this configuration, as actuator 515 moves actuator shaft 510 upward toward
needle
210, mechanical linkage interface 545 also moves upward toward needle 210. In
other embodiments of the present invention, mechanical linkage interface 545
and
actuator shaft 510 are a single component. In other words, a shaft connected
to
actuator 515 includes both actuator shaft 510 and mechanical linkage interface
545 as
a single assembly.
Controller 305 is connected via interface 535 to limited reuse assembly
interface connecter 553. Limited reuse assembly interface connecter 553 is
located on
a top surface of limited reuse assembly housing 255 adjacent to mechanical
linkage
interface 545. In this manner, both limited reuse assembly interface connector
553
and mechanical linkage interface 545 are adapted to be connected with tip
interface
connector 453 and plunger interface 420, respectively.
Controller 305 and actuator 515 are connected by an interface (not shown).
This interface (not shown) allows controller 305 to control the operation of
actuator
515. In addition, an interface (not shown) between power source 505 and
controller
305 allows controller 305 to control operation of power source 505. In such a
case,
controller 305 may control the charging and the discharging of power source
505
when power source 505 is a rechargeable battery.
Controller 305 is typically an integrated circuit with power, input, and
output
pins capable of performing logic functions. In various embodiments, controller
305 is
a targeted device controller. In such a case, controller 305 performs specific
control
functions targeted to a specific device or component, such as a temperature
control
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device or a power supply. For example, a temperature control device controller
has
the basic functionality to control a temperature control device. In other
embodiments,
controller 305 is a microprocessor. In such a case, controller 305 is
programmable so
that it can function to control more than one component of the device. In
other cases,
controller 305 is not a programmable microprocessor, but instead is a special
purpose
controller configured to control different components that perform different
functions.
While depicted as one component in Figure 5, controller 305 may be made of
many
different components or integrated circuits.
Tip segment 205 is adapted to mate with or attach to limited reuse assembly
250. In the embodiment of Figure 5, plunger interface 420 located on a bottom
surface of plunger 415 is adapted to mate with mechanical linkage interface
545
located near a top surface of limited reuse assembly housing 255. In addition,
tip
interface connector 453 is adapted to connect with limited reuse assembly
interface
connector 553. When tip segment 205 is connected to limited reuse assembly 250
in
this manner, actuator 515 and actuator shaft 510 are adapted to drive plunger
415
upward toward needle 210. In addition, an interface is formed between
controller 305
and temperature control device 450. A signal can pass from controller 305 to
temperature control device 450 through interface 535, limited reuse assembly
interface connector 553, tip interface connector 453, and interface 530.
In operation, when tip segment 205 is connected to limited reuse assembly
250, controller 305 controls the operation of actuator 515. When actuator 515
is
actuated, actuator shaft 510 is moved upward toward needle 210. In turn,
mechanical
linkage interface 545, which is mated with plunger interface 420, moves
plunger 415
upward toward needle 210. A substance located in dispensing chamber 405 is
then
expelled through needle 210.
In addition, controller 305 controls the operation of temperature control
device
450. Temperature control device 450 is adapted to heat and/or cool dispensing
chamber housing 425 and its contents. Since dispensing chamber housing 425 is
at
least partially thermally conductive, heating or cooling dispensing chamber
housing
425 heats or cools a substance located in dispensing chamber 405. Temperature
information can be transferred from thermal sensor 460 through interface 530,
tip
interface connector 453, limited reuse assembly interface connector 553, and
interface
535 back to controller 305. This temperature information can be used to
control the
operation of temperature control device 450. When temperature control device
450 is
a heater, controller 305 controls the amount of current that is sent to
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control device 450. The more current sent to temperature control device 450,
the
hotter it gets. In such a manner, controller 305 can use a feed back loop
utilizing
information from thermal sensor 460 to control the operation of temperature
control
device 450. Any suitable type of control algorithm, such as a proportional
integral
derivative (PID) algorithm, can be used to control the operation of
temperature
control device 450.
Figure 6 is a cross section view of a disposable tip segment for an ophthalmic
medical device according to an embodiment of the present invention. In Figure
6,
disposable tip segment 205 includes housing 215, needle 210, plunger 415,
plunger
interface 420, dispensing chamber 405, dispensing chamber housing 425,
assembly
555, temperature control device 450, thermal sensor 460, optional luer 430,
tip
interface connectors 451, 452, and 453, and interfaces 461, 462, and 463.
Disposable
tip segment 205 operates as a disposable injection device.
In the embodiment of Figure 6, plunger 415 is located in dispensing chamber
housing 425. Dispensing chamber 405 is enclosed by dispensing chamber housing
425 and plunger 415. Plunger 415 forms a fluid seal with the interior surface
of
dispensing chamber housing 425. Needle 210 is fluidly coupled to dispensing
chamber 405. In this manner, a substance located in dispensing chamber 405 can
be
contacted by plunger 415 and pushed out of needle 210. Needle 210 may be
secured
to disposable tip segment 205 by an optional luer 430 or may be permanently
attached. Temperature control device 450 is located on dispensing chamber
housing
425 and at least partially surrounds dispensing chamber 405. Housing 215 forms
an
outer skin on disposable tip segment 205.
In various embodiments of the present invention, temperature control device
450 is a heating and/or a cooling device. Temperature control device 450 is in
thermal contact with dispensing chamber housing 425. As such, temperature
control
device 450 is capable of changing the temperature of the substance in
dispensing
chamber 405.
In Figure 6, plunger 415 includes an o-ring. The o-ring seals against an
interior surface of dispensing chamber housing 425. In this manner, a sterile
seal is
maintained thus preventing contamination of the substance in dispensing
chamber
405. Plunger 415 may be made of any suitable material, such as, for example,
glass,
stainless steel, or a polymer. The o-ring is typically made of rubber or a
polymer.
Other types of seals may also be used. For example, plunger 415 may contain an
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annular ring that is located around a periphery of plunger 415 so that the
annular ring
contacts the interior surface of dispensing chamber 425. This annular ring can
seal
the plunger against the interior surface of dispensing chamber 425. In such a
case, the
annular ring may be integral with plunger 415, and plunger 415 may be made of
rubber or a polymer. Plunger interface 420 may be of any suitable shape. For
example, plunger interface may be substantially bowl shaped as shown, or it
may be
substantially flat, conical, or spherical. It may also include a lip or other
similar
feature.
Tip interface connectors 451, 452, and 453 serve to provide a connection
between tip segment 205 and a limited reuse assembly. Interface 461 connects
thermal sensor 460 to tip interface connector 451. Interface 462 connects
temperature
control device 450 to tip interface connector 452. Interface 463 connects
assembly
555 to tip interface connector 453.
Assembly 555 can include any of a number of different components. In one
embodiment, assembly 555 contains a fuse that is blown when the heat button is
activated or after disposable tip segment 205 is used. In this manner, the
fuse
prevents reuse of disposable tip segment 205. In another embodiment, assembly
555
includes a memory device that stores information about the type of disposable
tip
segment 205, dosage information, temperature information, plunger movement
information, or any other type of information that identifies a characteristic
of
disposable tip segment 205 or a manner in which disposable tip segment 205 is
operated. In other embodiments, assembly 205 includes a hard-wired memory
device,
like a NAND flash IC, an RFID tag, a hard-wired wired circuit that can store a
representation of data, like a series of fuses and resistors connected in
parallel or other
type of device.
A substance to be delivered into an eye, typically a drug, is located in
dispensing chamber 405. In this manner, the drug is contacted by the inner
surface of
dispensing chamber housing 425 and one face of plunger 415. Temperature
control
device 450 is in thermal contact with dispensing chamber housing 425. In this
manner, temperature control device 450 is adapted to control the temperature
of the
contents of dispensing chamber 405.
In various embodiments of the present invention, temperature control device
450 heats a phase transition compound that is located in dispensing chamber
405.
This phase transition compound carries a drug that is to be injected into the
eye. A
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phase transition compound is in a solid or semi-solid state at lower
temperatures and
in a more liquid state at higher temperatures. Such a substance can be heated
by
temperature control device 450 to a more liquid state and injected into the
eye where
it forms a bolus that erodes over time. Likewise, a reverse gelation compound
may be
used. A reverse gelation compound is in a solid or semi-solid state at higher
temperatures and in a more liquid state at lower temperatures. Such a compound
can
be cooled by temperature control device 450 to a more liquid state and
injected into
the eye where it forms a bolus that erodes over time. As such, temperature
control
device 450 may be a device that heats a substance in dispensing chamber 405 or
a
device that cools a substance in dispensing chamber 405 (or a combination of
both).
After being delivered into the eye, a phase transition compound or reverse
gelation
compound erodes over time providing a quantity of drug over an extended period
of
time. Using a phase transition compound or reverse gelation compound provides
better drug dosage with fewer injections.
Thermal sensor 460 provides temperature information to assist in controlling
the operation of temperature control device 450. Thermal sensor 460 may be
located
near dispensing chamber housing 425 and measures a temperature near dispensing
chamber housing 425. Thermal sensor 460 may also be located in thermal contact
with dispensing chamber housing 425, in which case it measures a temperature
of
dispensing chamber housing 425. In other embodiments, the temperature that
thermal
sensor 460 measures can be correlated to the temperature of the substance in
dispensing chamber 405. In other words, a measurement of the temperature of
dispensing chamber housing 425 can be used to calculate the temperature of the
substance located in dispensing chamber 405. Since the thermal characteristics
of
dispensing chamber housing 425 and the substance therein are known, and the
temperature of temperature control device 450 is controllable, an application
of
temperature control device for a specified period of time results in a
calculable change
in the temperature of the substance in dispensing chamber 405. Thermal sensor
460
may be any of a number of different devices that can provide temperature
information. For example, thermal sensor 460 may be a thermocouple or a
resistive
device whose resistance varies with temperature.
In one embodiment of the present invention, the substance located in
dispensing chamber 405 is a drug that is preloaded into the dispensing
chamber. In
such a case, disposable tip segment 205 is appropriate as a single use
consumable
product. Such a disposable product can be assembled at a factory with a dosage
of a
drug installed.
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When a drug is preloaded into dispensing chamber 405, a set quantity of the
drug can be preloaded. For example, 100 microliters of a drug can be loaded
into
dispensing chamber 405, and any quantity up to 100 microliters can be
dispensed.
Information about the amount of drug in dispensing chamber 205 and other
dosage
information can be stored in assembly 555. In such a case, plunger 415 can be
moved
a precise distance to deliver a precise dosage of drug from dispensing chamber
405,
through needle 210, and into an eye. This provides for flexibility of dosing
and for
ease of assembly.
Figure 7 is a cross section view of a disposable tip segment for an ophthalmic
medical device according to an embodiment of the present invention. In Figure
7,
disposable tip segment 205 includes housing 215, needle 210, plunger 415,
plunger
interface 420, dispensing chamber 405, dispensing chamber housing 425,
assembly
555, temperature control device 450, thermal sensor 460, optional fuer 430,
tip
interface connectors 452 and 453, interfaces 462 and 463, and lock mechanism
471.
The embodiment of Figure 7 functions like the embodiment of Figure 6. The
various components of tip segment 205 of Figure 7 have the same
characteristics and
operate in substantially the same way as like components of Figure 6. Lock
mechanism 471 serves to attach tip segment 205 to a limited reuse assembly. A
mating mechanism, like lock mechanism 265, on a limited reuse assembly,
attaches to
lock mechanism 471 and secures tip segment 205 to a limited reuse assembly.
Figure 8 is a cross section view of a disposable tip segment and a partial
view
of a limited reuse assembly according to an embodiment of the present
invention. In
Figure 7, disposable tip segment 205 includes housing 215, needle 210, plunger
415,
plunger interface 420, dispensing chamber 405, dispensing chamber housing 425,
RFID tag 1110, temperature control device 450, tip interface connector 452,
and
interface 462. The partial view of a limited reuse assembly depicts mechanical
linkage interface 545, actuator shaft 510, interface 535, limited reuse
assembly
interface connector 552, RFID reader 1120, and RFID interface 1130.
The embodiment of Figure 8 functions like the embodiments of Figures 6 and
7. The various components of the tip segment 205 of Figure 8 have the same
characteristics and operate in substantially the same way as the like
components of
Figures 6 and 7. However, the embodiment of Figure 8 uses an RFID system
rather
than a wired assembly 555 to store and transfer information. RFID reader 1120
is
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located near the top of a limited reuse assembly adjacent to mechanical
linkage
interface 545. RFID tag is located at the bottom of tip segment 205. RFID
reader
1120 is designed to read information from RFID tag 1110. RFID interface 1130
is
connected to controller 305 (not shown).
RFID tag 1110 is configured to hold the same type of information that
assembly 555 may hold in the embodiments of Figures 5-7. In this manner, RFID
tag
1110 is another type of memory. However, as is commonly know, RFID tag 1110
does not require a wired connection to RFID reader 1120. In this manner, a
wireless
connection between the tip segment 205 (RFID tag 1110) and a limited reuse
assembly (RFID reader 1120) can be established.
In one type of RFID system, a passive RFID system, RFID tag 1110 does not
have a power supply. Instead, the passive RFID tag relies on the
electromagnetic
field produced by RFID reader 1120 for its power. The electromagnetic field
produced by RFID reader 1120 and emitted from the RFID reader antenna (not
shown) induces a small electrical current in RFID tag 1110. This small
electrical
current allows RFID tag 1110 to operate. In this passive system the RFID tag
is
designed to collect power from the electromagnetic field emitted by the RFID
reader
1120 and to transmit an outbound signal that is received by RFID reader 1120.
In operation the RFID reader antenna (not shown) transmits a signal produced
by RFID reader 1120. The RFID tag antenna (not shown) receives this signal and
a
small current is induced in RFID tag 1110. This small current powers RFID tag
1110.
RFID tag 1110 can then transmit a signal through its RFID tag antenna to RFID
reader antenna and RFID reader 1120 itself. In this manner, RFID tag 1110 and
RFID
reader 1120 can communicate with each over a radio frequency link. RFID tag
1110
transmits information, such as dosage information or tip segment information,
through
RFID tag antenna to RFID reader 1120. This information is received by RFID
reader
1120. In this manner, information can be transferred from the tip segment 205
to the
limited reuse assembly. RFID reader 1120 can transmit information to RFID tag
1110
in a similar fashion. For example, RFID reader 1120 can transmit information
such as
dosage information over the radio frequency signal emitted by RFID reader
1120.
RFID tag 1120 receives this radio frequency signal with the information. RFID
tag
1110 can then store this information.
While the embodiment of Figure 8 is described as having an RFID system, any
other type of wireless system can be used to transfer information between a
limited
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reuse assembly 250 and tip segment 205. For example a Bluetooth protocol maybe
used to establish a communications link between a limited reuse assembly 250
and tip
segment 205. Information can then be transferred between a limited reuse
assembly
250 and a tip segment 205 over this communication link. Other embodiments used
to
transfer information include an infrared protocol, 802.11, fire wire, or other
wireless
protocol.
In one embodiment, RFID tag 1110 (or assembly 555) contains dosage
information. Information about a proper drug dosage for a drug contained in
dispensing chamber 405 may be contained on RFID tag 1110 (or assembly 555). In
such a case, controller 305 can read the dosage information from RFID tag 1110
(or
assembly 555) and operate actuator 515 in a manner suitable to deliver the
proper
dosage. For example, 100 microliters may be contained within dispensing
chamber
405. Information stating that a dosage of 20 microliters is to be delivered
into an eye
maybe stored on RFID tag 1110 (or assembly 555). In such a case, controller
305
reads the dosage information (that 20 microliters should be delivered into the
eye)
from RFID tag 1110 (or assembly 555). Controller 305 can then operate actuator
515
to deliver the 20 microliter dosage. Controller 305 can cause actuator 515 to
move
actuator shaft 510 and mechanical linkage interface 545 a set distance related
to a
dosage of 20 microliters. In such a case, plunger 415 is moved this set
distance so
that only 20 microliters of a drug is expelled from needle 210 and into an
eye.
In another embodiment consistent with the principles of the present invention,
controller 305 may calculate a distance that plunger 415 must be moved to
deliver the
desired dosage. For example, if dosage information corresponding to a drug
dosage
of 20 microliters is read from RFID tag 1110 (or assembly 555) by controller
305,
then controller 305 may use this information to calculate a proper distance
that
plunger 415 must be moved. Since the volume of dispensing chamber 405 as well
as
the volume of a drug loaded in dispensing chamber 405 is known, a distance
that
plunger 415 must be moved to deliver that required dosage can be calculated by
controller 305. When dispensing chamber 405 has a cylindrical shape, the
volume of
the dispensing chamber can be calculated by using the cross section area of
the
cylinder (the area of a circle) times the height of the dispensing chamber.
This simple
mathematical formula can be used to calculate the total volume of the
dispensing
chamber 405. Since the cross section area of dispensing chamber 405 is
constant for
any given application, the height which corresponds to a distance that plunger
415
travels can be calculated for any dosage amount.
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For example, assume that 100 microliters of a drug is loaded into dispensing
chamber 405 and that the cross sectional area of dispensing chamber 405 is
ten.
When dispensing chamber 405 is in the shape of a cylinder, the height of that
cylinder
is also 10. To deliver a dosage of 20 microliters which corresponds to 20% of
the
total volume of dispensing chamber 405, it is necessary to move plunger 415
upward
toward needle 210 a distance of two. In other words, a dosage of 20
microliters
corresponds to 20% of the total volume of dispensing chamber 405. In such a
case,
plunger 415 should be moved upward toward needle 210 a distance equal to 20%
of
the total height of dispensing chamber 405. Controller 305 can then control
actuator
515 such that actuator shaft 510 drives plunger 415 upwards a distance of 20%
of the
total height of dispensing chamber 405.
In addition, controller 305 may read information about a rate at which plunger
415 should be moved in order to properly deliver a dosage of drug. In such a
case,
controller 305 reads information about the rate of drug delivery from RFID tag
1110
(or assembly 555) and uses that information to operate actuator 515 to drive
plunger
415 at that rate. The rate at which plunger 415 moves may be fixed or
variable. In
some applications, it may be desirable to move plunger 415 faster than in
other
applications. For example, when the drug contained in dispensing chamber 405
is a
drug that should be heated before being injected into an eye, it maybe
desirable to
drive plunger 415 at a rate such that the heated drug does not cool and clog
needle
210. In other applications, it maybe desirable to move plunger 415 slowly in
order to
improve the delivery of a drug contained in dispensing chamber 405.
RFID tag 1110 (or assembly 555) may also include any other type of
information related to the delivery of a drug. For example, RFID tag 1110 (or
assembly 555) may include information about the type of drug contained in
dispensing chamber 405, various characteristics of that drug, or other
characteristics
of a proper dosage or a proper delivery of that drug. In addition, RFID tag
1110 (or
assembly 555) may contain safety information, information about the proper
operation of tip segment 205, or any other information related to the tip
segment or
limited reuse assembly.
In another embodiment consistent with the principles of the present invention,
a dosage may be selectable by the medical professional who is administering
the drug.
In such a case, an input device (not shown) located on limited reuse assembly
250 or
on tip segment 205 may enable a doctor to select the desired drug dosage. In
such a
case, controller 305 receives the desired drug dosage and operates actuator
515 to
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move plunger 415 the required distance to deliver the desired dosage. Such a
user
selectable dosage scheme may be implemented simply by adding an extra input
device.
It may be desirable to include dosage information on RFID tag 1110 (or
assembly 555) so that a dosing error is less likely to occur. In such a case,
a number
of different drug delivery tip segments 205 maybe manufactured and loaded with
a
drug at the factory. Dosage information can also be loaded onto RFID tag 1110
(or
assembly 555) at the factory. In such a case, a number of different tip
segments each
with the same amount of drug contained in the dispensing chamber 405 but with
different dosage information stored on RFID tag 1110 (or assembly 555) can be
manufactured and shipped. A doctor can then order the tip segment 205 with the
required dosage information on the RFID tag 1110 (or assembly 555). Packaging
can
be clearly labeled to identify the dosage information so that the proper
dosage is
administered to a patient.
Figure 9A is a cross section view of a disposable tip segment for an
ophthalmic medical device according to an embodiment of the present invention.
In
Figure 9, disposable tip segment 205 includes housing 215, needle 210, plunger
415,
plunger shaft 417, plunger interface 420, dispensing chamber 405, dispensing
chamber housing 425, assembly 555, temperature control device 450, thermal
sensor
460, optional luer 430, tip interface connectors 452 and 453, interfaces 462
and 463,
and tabs 472 and 473.
The various components of tip segment 205 of Figure 9 have the same
characteristics and operate in substantially the same way as like components
of
Figures 5-8. The embodiment of Figure 9 includes two tabs 472 and 473 that
engage
slots in a limited reuse assembly. After these two tabs 472 and 473 are
inserted into
the slots, the tip assembly 205 is rotated to lock it into place on a limited
reuse
assembly. The two tabs 472 and 473 may be of different shapes or sizes so as
to
provide a proper interface between tip segment 205 and a limited reuse
assembly.
When these two tabs 472 and 473 are shaped or sized differently, then tip
segment
405 only fits on a limited reuse assembly in one orientation. In other
embodiments of
the present invention, different shaped or sized tabs can be used with
different shaped
or sized slots on different limited reuse assemblies. In this manner, a number
of
different limited reuse assemblies may be manufactured with different shaped
or sized
slots to accommodate tip segments 205 with complimentary shaped or sized tabs.
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In addition, the embodiment of Figure 9 includes a plunger shaft 417 that is
connected to plunger 415. In this embodiment, plunger 415 may be over-molded
onto
plunger shaft 417. Plunger shaft 417 is generally cylindrical in shape with a
middle
diameter that is less than a diameter on its distal and proximal ends. Plunger
interface
420 is a surface on the proximal end of plunger shaft 417. Plunger shaft 417
is
typically made of a rigid material such as stainless steel. Plunger 415 is
made of a
rubber or polymer material. In another embodiment of the present invention,
the
distal end of plunger shaft 417 has a lip over which plunger 415 can be
applied.
Plunger 415 can be press-fitted onto plunger shaft 417 and is retained in
place by a lip
on the distal end of plunger shaft 417. This allows for easier assembly.
Instead of
over molding plunger 415 onto a shaft, plunger 415 can be manufactured as a
separate
part and pushed onto the distal end of plunger shaft 417. Plunger interface
420 can be
of any suitable shape.
Figure 9B is an end view of the tip segment of Figure 9A. Figure 9B depicts
the end of tip segment 205 farthest from needle 210. This end interfaces with
a
limited reuse assembly. Pictured are housing 215, plunger interface 420, tip
interface
connectors 451, 452 453, 454, 455, and 456, tabs 472 and 473, and alignment
slot
481.
In the embodiment of Figure 9B, one end of plunger interface 420 is not
completely circular. It has a flat portion that is designed to align with a
mechanical
linkage interface with a similar cross-sectional shape. This optional feature
is
designed to allow proper alignment of a tip segment and a limited reuse
assembly. In
other embodiments of the present invention, the cross section view of one end
of
plunger interface 420 is circular.
The embodiment of Figure 9B also includes an optional alignment slot 481 to
assist in properly aligning a tip segment with a limited reuse assembly.
Alignment
slot 481 interfaces with an alignment pin on a limited reuse assembly (581 as
shown
in Figure 11). In another embodiment of the present invention, tabs 472 and
473 have
different sizes. Alternatively, tabs 472 and 473 may have different shapes.
The two
tabs 472 and 473 also assist in aligning a tip segment with a limited reuse
assembly by
interfacing with slots 572 and 573 of Figure 11.
In one embodiment consistent with the principles of the present invention, a
tip segment is placed on a limited reuse assembly such that tabs 472 and 473
are
inserted into slots 572 and 573. The tip segment is then rotated with respect
to the
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limited reuse assembly so that tabs 472 and 473 are retained in slots 572 and
573.
Alignment pin 581 and alignment slot 481 are then properly aligned.
Connectors 451, 452, 453, 454, 455, and 456 electrically link a tip segment to
a limited reuse assembly. Connectors 451, 452, 453, 454, 455, and 456
interface with
similar connectors 551, 552, 553, 554, 557, and 556, respectively, on a
limited reuse
assembly (as shown in Figure 11). These connectors provide a path for signals
to pass
between a tip segment and a limited reuse assembly.
Figures 10A-10D are schematic depictions of four different circuits that may
be included in embodiments of the present invention. Figure 10A shows one of
many
different configurations for temperature control device 450. In Figure 10A,
temperature control device 450 is connected to connectors 452 and 455. Power
and/or
control signals are provided to temperature control device 450 through
connectors 452
and 455.
Figure 10B shows one of many different configurations for thermal sensor
460. In Figure 10B, thermal sensor 460 is connected to connectors 451 and 454.
Signals are received from thermal sensor 460 through connectors 451 and 454.
Figure 10C shows one of many different configurations for a fuse 1011. Fuse
1011 may be contained within assembly 555 or may be implemented as shown in
Figure IOC. In Figure 10C, fuse 1011 is connected between connectors 453 and
456.
In this embodiment, fuse 1011 acts to ensure that the tip assembly is a single-
use
device. Fuse 1011 is blown when the heat button is activated or after
disposable tip
segment 205 is used. As discussed, a controller in a limited reuse assembly
detects
when the connected tip segment has been used and directs an increased current
to pass
through fuse 1011 thus blowing the fuse. When fuse 1011 is blown, the tip
segment is
no longer operable and must be discarded.
Figure 10D shows one of many different configurations for assembly 555. In
Figure 10D, assembly 555 is connected to connectors 453 and 456. Power and/or
control signals are provided to assembly 555 through connectors 453 and 456.
Many other configurations of connectors 451, 452 453, 454, 455, and 456 may
be implemented. For example, while six connectors are shown, any number of
connectors may be implemented. Further, any combination of different circuits
may
be contained in a tip segment.
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Figure 11 is end view of a limited reuse assembly according to the principles
of the present invention. The end of the limited reuse assembly shown in
Figure 11
interfaces with the end of the tip assembly shown in Figure 9B. The end view
of
limited reuse assembly depicted in Figure 11 shows housing 255, mechanical
linkage
interface 545, limited reuse assembly interface connectors 551, 552, 553, 554,
557,
and 556, slots 572 and 573, and alignment pin 581.
In the embodiment of Figure 11, one end of mechanical linkage interface 545
is not completely circular. It has a flat portion that is designed to align
with a plunger
interface with a similar cross-sectional shape. This optional feature is
designed to
allow proper alignment of a tip segment and a limited reuse assembly. In other
embodiments of the present invention, the cross section view of one end of
mechanical linkage interface 545 is circular.
The embodiment of Figure 11 also includes an optional alignment slot 581 to
assist in properly aligning a tip segment with a limited reuse assembly.
Alignment
pin 581 interfaces with an alignment slot on a tip segment (481 as shown in
Figure
9B). In another embodiment of the present invention, slots 572 and 573 have
different sizes. Alternatively, slots 572 and 573 may have different shapes.
The two
slots 572 and 573 also assist in aligning a tip segment with a limited reuse
assembly
by interfacing with tabs 472 and 473 of the tip segment shown in Figure 9B.
Connectors 551, 552, 553, 554, 557, and 556 electrically link a tip segment to
a limited reuse assembly. Connectors 551, 552, 553, 554, 557, and 556
interface with
connectors 451, 452 453, 454, 455, and 456 on a tip segment (as shown in
Figure 9B).
These connectors provide a path for signals to pass between a tip segment and
a
limited reuse assembly.
Figure 12 is a cross section view of a limited reuse assembly according to an
embodiment of the present invention. In Figure 12, limited reuse assembly 250
includes mechanical linkage interface 545, actuator shaft 510, actuator 515,
power
source 505, controller 305, limited reuse assembly housing 255, interface 535,
limited
reuse assembly interface connector 551, displacement sensor 1215, power source
controller 444, and inductive element 1225.
Displacement sensor 1215 measures the movement of actuator shaft 510.
Displacement sensor may be, among other things, an optical rotary encoder, a
linear
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encoder, a current sensing circuit (Hall sensor), a rotary potentiometer, or a
linear
potentiometer. In other embodiments, displacement sensor is capable of
detecting if
=
actuator 515 stalls. For example, a Hall sensor can detect an increased
current draw
by actuator 515 that indicates a stall condition. Displacement sensor 1215 may
also
measure back EMF from actuator 515. Displacement sensor 1215 may be comprised
of a single component or multiple components. In one embodiment consistent
with
the principles of the present invention, displacement sensor 1215 includes a
device to
measure the distance that actuator shaft 510 travels and a device to detect if
actuator
515 stalls.
Displacement sensor 1215 measures the position of actuator shaft 510. Since
mechanical linkage interface 545 is connected to actuator shaft 510,
displacement
sensor 1215 also measures its position. Such a displacement sensor 1215 can be
used
to determine if a full dosage is delivered. If displacement sensor 1215
detects that
actuator shaft 510 has traveled a certain distance corresponding to a movement
of
mechanical linkage interface 545 and plunger 415, then it is known that a
certain
dosage has been expelled from needle 210. In the case where a drug is to be
delivered
into an eye, displacement sensor 1215 provides information about the movement
of
actuator shaft 510 that can be used to determine if the full dosage has been
delivered.
In some cases, actuator 515 may stall, thus failing to drive actuator shaft
510,
mechanical linkage interface 545, and plunger 415 the proper distance to
deliver a full
dosage of a drug into an eye. In such a case, displacement sensor 1215
measures the
distance that actuator shaft 510, mechanical linkage interface 545, and
plunger 415
have traveled. From this distance information, a delivered amount of drug can
be
calculated. For example, when the dispensing chamber 405 is cylindrical in
shape, its
circular cross-sectional area is known. The distance measured by displacement
sensor
1215 then becomes the height of the cylinder, and the volume of displacement
can be
easily calculated (by controller 305, for example). This delivered amount can
be
communicated, along with a stall indication, via a display, such as display
320 (Figure
3).
Displacement sensor 1215 may also provide other information useful in the
drug delivery process. For example, when a tip segment is connected to a
limited
reuse assembly, actuator shaft 510 may be withdrawn or brought to a homed
position
for connection of a tip segment. Displacement sensor 1215 can measure the
movement of actuator shaft 510 to this homed position. Actuator shaft 510 may
be
placed in a homed position to allow a tip segment to be attached to a limited
reuse
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assembly or prior to delivery of a drug. In one embodiment, information read
from
displacement sensor 1215 is used to confirm that actuator shaft 510 is in a
homed
position before actuator 515 is activated to deliver a drug into the eye.
The embodiment of Figure 12 also includes power source controller 444 and
inductive element 1225. These two components control the charging of power
source
505 when power source 505 is, for example, a rechargeable battery. Power
source
controller 444 includes circuitry that may perform any of a number of
different
functions related to the charging, monitoring, and maintenance of power source
505.
In other embodiments, power source controller 444 may be implemented in or
integrated into controller 305.
In one embodiment of the present invention, power source controller 444 (or
controller 305, as the case may be) counts the number of times that limited
reuse
assembly 250 has been used. After the count has reached a predetermined safe
number of uses, limited reuse assembly 250 is disabled. Alternatively, power
source
controller 444 (or controller 305, as the case may be) counts the number of
times
power source 505 has been charged (the number of charge cycles to which power
source 505 has been subjected). When the count reaches a predetermined
threshold,
limited reuse assembly 250 is disabled. In other embodiments of the present
invention power source controller 444 (or controller 305, as the case may be)
detects
fault conditions or other unsafe conditions of power source 505 and prevents
further
use of limited reuse assembly 250.
To charge power source 505, a current is induced in inductive element 1225
when it is placed near another inductive element in a charging base (not
shown). This
induced current charges power source 505.
Figure 13 is a cross section view of a limited reuse assembly according to an
embodiment of the present invention. In Figure 12, limited reuse assembly 250
includes mechanical linkage interface 545, actuator shaft 510, actuator 515,
power
source 505, controller 305, limited reuse assembly housing 255, interface 535,
limited
reuse assembly interface connector 551, displacement sensor 1215, power source
controller 444, and charging contacts 1235.
In the embodiment of Figure 13, contacts 1235 interface with contacts on a
charging base (not shown) to provide power to power source 505. In one
embodiment, contacts 1235 are a USB-type connection such as those used by
portable
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electronic devices with docking stations. In one
embodiment, a Molex
CradleConTM connector is employed. Other types of connectors may also be used.
Figures 14 and 15 are cross section views of two subassemblies according to
the principles of the present invention. Each of these subassemblies depicts
the path
from the actuator 515 to the needle 210. Figure 14 depicts a mechanical
linkage
interface 545 that is rigidly connected to actuator shaft 510, while Figure 15
depicts a
mechanical linkage assembly 545 with a ball joint 805. The use of ball joint
805
assists in aligning mechanical linkage interface 545 with plunger interface
420.
In Figure 14, actuator 515 has an actuator shaft 510 that is rigidly connected
to
mechanical linkage interface 545. Mechanical linkage interface mates with
plunger
interface 420. Plunger 415 is disposed within dispensing chamber housing 425
and is
sealed against an inside surface of dispensing chamber housing 425. Dispensing
chamber 405 is bounded by an interior surface of dispensing chamber housing
425
and the distal face of plunger 415. Temperature control device 450 at least
partially
surrounds dispensing chamber housing 425. Needle 210 is fluidly coupled to
dispensing chamber 405.
In Figure 15, actuator 515 has an actuator shaft 510 that is connected to
shaft
810 via a ball joint. Mechanical linkage interface 545 is rotatably connected
to shaft
810 via ball joint 805. Mechanical linkage interface mates with plunger
interface 420.
Plunger 415 is disposed within dispensing chamber housing 425 and is sealed
against
an inside surface of dispensing chamber housing 425. Dispensing chamber 405 is
bounded by an interior surface of dispensing chamber housing 425 and the
distal face
of plunger 415. Temperature control device 450 at least partially surrounds
dispensing chamber housing 425. Needle 210 is fluidly coupled to dispensing
chamber 405.
In Figures 14 and 15, actuator 515 drives actuator shaft 510 upward (in a
direction towards needle 210). In turn, mechanical linkage interface 545 is
also
driven upward. When mechanical linkage interface 545 is mated with plunger
interface 420, plunger 420 is also moved upward. A substance contained in
dispensing chamber 405 is expelled through needle 210. In this manner, motion
and
force is transferred from actuator shaft 510 to mechanical linkage interface
545 to
plunger 415.
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When dispensing chamber 405 contains a drug that is to be delivered into an
eye, the configurations of Figures 14-15 eliminate reflux when the needle is
removed
from the eye. Motion of the plunger 415 is in a single direction (a direction
that
expels the drug in dispensing chamber 405). When mechanical linkage interface
545
is moved in a direction away from needle 210, for example, after the drug has
been
injected into the eye, the plunger 415 remains in place. Since plunger 415 is
not
rigidly connected to mechanical linkage interface 545, plunger 415 is not
retracted as
mechanical linkage interface 545 is retracted.
Figure 16 is a cross section diagram of the limited reuse assembly of Figure
13
and a charging base. In Figure 16, a bottom surface of limited reuse assembly
250
interfaces with charging base 1615. When limited reuse assembly 250 is resting
in
charging base 1615, power source 505 can be charged. After being charged,
limited
reuse assembly 250 can be removed from charging base 1615. In one embodiment
of
the present invention, limited reuse assembly 250 with an attached tip segment
205 is
placed in charging base 1615 and a substance located in dispensing chamber 405
is
heated or cooled by temperature control device 450. In this manner, charging
base
1615 provides the power for temperature control device 450. When the substance
located in dispensing chamber 405 has reached the proper temperature (as
determined
from information from thermal sensor 460), limited reuse assembly 250 with
attached
tip segment 205 can be removed from the charging base. This saves power source
505 for the injection process when limited reuse assembly 250 and attached tip
segment 205 are removed from charging base 1615.
Figures 17A and 17B are flow charts of one method of injecting a substance
into an eye according to the principles of the present invention. In 1705, a
connection
between a tip segment and a limited reuse assembly is recognized. In 1710, the
type
of tip segment that was connected to the limited reuse assembly is identified.
For
example, a drug delivery tip segment or type of drug delivery tip segment may
be
identified. Such identification may occur by reading information from the tip
segment, for example, by reading information from memory or RFID tag. In 1715,
dosage information is received from the tip segment. Like the information
relating to
the type of tip segment, dosage information may be read from a memory device
in the
tip segment by a controller, RFID reader, or similar device in the limited
reuse
assembly.
In 1720, a temperature control device is activated to alter the temperature of
the substance that is located in the dispensing chamber. The substance may be
heated
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or cooled as previously described. In addition, the heating or cooling may
only take
place when the tip segment and limited reuse assembly are located on a
charging base.
In 1725, temperature information is received from a thermal sensor that is
located
near the dispensing chamber in which the substance is located. In 1730, this
temperature information is used to control the temperature control device to
regulate
the temperature of the substance.
In 1735, the actuator shaft is moved to a homed position. For example, the
actuator shaft may be completely retracted to establish a homed position. The
homed
position can establish a reference point for a displacement sensor. In other
words, the
displacement sensor can begin measuring movement of the actuator shaft from
the
homed position. In 1740, the actuator shaft is moved until the mechanical
linkage
interface (which is integral with or connected to the actuator shaft) contacts
the
plunger interface. In this position, any further movement of the actuator
shaft results
in an expulsion of the substance from the dispensing chamber. When the
mechanical
linkage interface is in contact with the plunger interface, the device is
ready to be used
to inject the substance into the eye. This step is taken before injecting the
substance
into the eye so that the substance can be maintained at a proper temperature
for the
injection. For example, the substance may be heated or cooled while the tip
segment
and limited reuse assembly are located on a charging base. When the tip
segment and
limited reuse assembly are removed from the charging base, the doctor may have
a
limited period of time to perform the injection before the temperature of the
substance
falls outside of the proper temperature range. Having the mechanical linkage
interface in contact with the plunger interface allows for an injection to be
performed
in a short amount of time.
In 1745, an input is received indicating that the substance is to be delivered
into the eye. For example the doctor may press a button that sends a signal to
the
controller indicating that the actuator is to be activated to deliver the
substance. In
1750, the dosage information is used to control the operation of the actuator
to deliver
the proper dosage at the proper rate. The substance is delivered into they eye
only
after it is in the proper temperature range. In 1755, information is received
from the
displacement sensor. This information indicates how far the actuator shaft has
traveled. The distance the actuator shaft has traveled correlates to a dosage.
The
further the shaft has traveled, the more the plunger has been displaced, and
the greater
the dosage delivered. In 1760, an indication of the dosage delivered is
provided. For
example, a successful injection, in which the complete dosage has been
successfully
delivered, may be indicated by a green light or by a number (representing the
amount
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of substance delivered in microliters). In an unsuccessful injection, the
amount of
substance actually delivered is displayed. In 1765, reuse of the tip segment
is
prevented, for example, by blowing a fuse in the tip segment.
Figure 18 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention. Figure 18 depicts
a
method of activating the temperature control device to heat or cool the
substance
located in the dispensing chamber while the tip segment and limited reuse
assembly
are located on a charging station. In 1805, a connection between a tip segment
and a
limited reuse assembly is recognized. In 1810, the type of tip segment is
identified.
In 1815, dosage information is received from the tip segment. In 1820, it is
determined whether or not the tip segment and limited reuse assembly are
located on
the charging base. If they are not located on the charging base, then in 1825,
the
system waits and returns to 1820. If the tip segment and limited reuse
assembly are
located on the charging base, then in 1830, the temperature control device is
activated
to alter a temperature of the substance contained in the dispensing chamber.
In 1835,
temperature information is received from a thermal sensor. In 1840, this
temperature
information is used to control the temperature control device.
Figure 19 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention. Figure 19 depicts
a
method relating to determining whether or not the proper dosage has been
delivered.
In 1910, the actuator is controlled based on a dosage and dosage rate
information.
The actuator moves the plunger to deliver the substance. In 1920, information
is
received from the displacement sensor indicating the distance that the
actuator shaft
has moved. In 1930, this distance information is used to determine if a proper
dosage
has been delivered. If the actuator shaft has moved the distance required to
deliver
the proper dosage, then in 1940, an indication that the proper dosage has been
delivered is provided. If the actuator shaft has not moved the distance
required to
deliver the proper dosage, then in 1950, the dosage delivered is calculated
based on
the distance the actuator shaft has moved. In 1960, an indication of the
delivered
dosage is provided.
Figure 20 is a flow chart of one method relating to injecting a substance into
an eye according to the principles of the present invention. Figure 20 relates
to the
situation in which the actuator shaft has stalled. In 2010, the actuator is
controlled
based on a dosage and dosage rate information. The actuator moves the plunger
to
deliver the substance. In 2020, data is received from a stall sensor. In 2030,
this data
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is used to detel ____________________________________________________ mine if
the actuator shaft has stalled. If the shaft has stalled, then in
2040, an indication of the stall condition is provided. In 2050, data is
received from a
displacement sensor indicating the distance that the actuator shaft moved. In
2060, an
indication of the delivered dosage is provided based on the distance
information. If
the shaft has not stalled, then in 2070, an indication is provided that the
proper dosage
has been delivered.
From the above, it may be appreciated that the present invention provides an
improved system and methods for delivering precise volumes of a substance into
an
eye. The present invention provides a single use, disposable delivery device
tip
segment that is capable of delivering a precise dosage. The tip segment
interfaces
with a limited reuse assembly. The present invention is illustrated herein by
example,
and various modifications may be made by a person of ordinary skill in the
art.
While the present invention is described in the context of a single-use drug
delivery device, the present invention encompasses any single-use medical
device that
interfaces with a source of electric power. Other embodiments of the invention
will
be apparent to those skilled in the art from consideration of the
specification and
practice of the invention disclosed herein.
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