Note: Descriptions are shown in the official language in which they were submitted.
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LOW CARRYOVER SAMPLE LIQUID ANALYSIS SYSTEM AND METHOD
This application is a divisional application of Canadian
application No. 2,0l9,519, filed June 21, 1990.
This invention relates to new and improved apparatus and
method for the automated analysis of successive sample liquids
with ultra low sample liquid carryover therebetween to maximize
the accuracy of the sample liquids analysis results.
Description of the Prior Art
Although apparatus and method for the highly effective,
automated analysis of successive sample liquids which bear a
number of significant similarities to those disclosed herein are
disclosed in United States Patent 4,629,703 issued December 16,
1986 to Kenneth F. Uffenhiemer for "Automated Analytical System"
and assigned to Technicon Instruments Corporation, Tarrytown, New
York, those significant similarities do not include the provision
for ultra low carryover between successive sample liquids as made
possible by the apparatus and method of this invention.
Although successive sample liquids aspiring and/or
dispensing probe means which are highly effective to that task
with very low sample liquid carryover are disclosed in United
States Patent 4, 121, 466 issued October 24, 1978 to Allen Reichler
et al., for "Liquid Dispenser with an Improved Probe" and
assigned to Technicon Instruments Corporation, Tarrytown, it may
be understood that the same, which rely solely on an isolation
liquid which is immiscible with the sample liquids and which
selectively wets the relevant probe walls to the substantial
exclusion of the sample liquids to minimize sample liquid
carryover, and which specifically rules out the utilization of a
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rinse liquid in combination with that isolation liquid to rinse
the relevant probe walls, simply cannot provide the ultra low
sample liquid carryover as provided by the apparatus and method
of this invention. In addition, and although the probe means are
only depicted schematically in United States Patent 4,121,466, it
is nonetheless clear that the same are totally distinct in
structural configuration from those of this invention.
Features of the Invention:
It is a feature of the invention to provide new and
improved apparatus and method for the automated analysis of
successive sample liquids with ultra low sample liquid carryover
therebetween, to thereby maximize the accuracy of the successive
sample liquids analysis results.
It is another feature of the invention to provide new and
improved successive sample liquids analysis apparatus and method
as above which are operable at high sample liquid analyses rates .
It is another feature of the invention to provide new and
improved successive sample liquids analysis apparatus and method
as above which are immediately applicable, without modification,
to a wide variety of different sample liquids analyses with
regard to different sample liquids analytes of interest.
It is another feature of the invention to provide new and
improved successive sample liquids analysis apparatus as above
which are of generally straightforward configuration and
manners) of operation, and which require the use of only readily
available components and materials of proven effectiveness and
dependability to the task at hand in the fabrication thereof.
It is a further feature of the invention to provide new
and improved successive sample liquids analysis system and method
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as above which are particularly, but not exclusively, adapted to
the automated performance of non-isotopic immunoassays on human
blood sera sample liquids with regard to a broad range of sample
liquid analytes, and wherein the ultra low sample liquid
carryover provided by the apparatus and method of the invention
is a requirement to the accuracy and validity of the immunoassay
results.
Summar~r of the Disclosure
As disclosed herein, the new and improved successive
sample liquids analysis system of the invention comprises sample
liquid aspirating and dispensing probe means with the improvement
comprising, means for aspirating a segment of a buffer-diluent
liquid followed by a segment of a sample liquid into the probe
means for merger of the buffer-diluent and sample liquid segments
in the probe means, and for subsequently dispensing the merged
buffer-diluent and sample liquid segments from the probe means,
thereby reducing sample liquid carryover upon the aspiration of
a segment of a succeeding sample liquid into the probe means.
In its method aspect the invention relates to a method
for the analysis of successive sample liquids through use of
sample liquid aspirating and dispensing probe means with the
improvement comprising the steps of, seriatim, aspirating a
segment of a buffer-diluent liquid into the probe means,
aspirating a segment of a sample liquid into the probe means for
merger of the buffer-diluent and sample liquids segments within
the probe means, and dispensing the merged buffer-diluent and
sample liquids segments from the probe means, thereby reducing
sample liquid carryover upon the aspiration of a segment of a
succeeding sample liquid into the probe means.
For use of the sample liquids analysis system in
application wherein relatively large volumes of the sample
liquids are aspirated and dispensed by the probe means, the
invention further includes aspiration of an appropriate
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surfactant liquid for mixture with the sample liquids in the
probe means; and this functions to better retain the integrity of
the sample liquids in the probe means to reduce sample liquid
carryover.
Descrit~tion of the Drawings
The above and other significant objects and advantages of
the invention are believed made clear by the following detailed
description thereof taken in conjunction with the accompanying
drawings wherein:
FIG. 1 is generally schematic view of an automated sample
liquids analysis system;
FIG. 2 is a top plan view of the sample liquid aspirating
and dispensing probe means of the system of FIG. 1;
FIG. 3 is a cross-sectional view taken essentially along
line 3-3 in FIG. 2;
FIG. 4 is a schematic diagram of a representative control
system for the sample liquids analysis system of FIG. 1; and
FIGS. 5, 6, 7 and 8 are respectively cross-sectional
views in the nature of FIG. 3 illustrating the respective
operational configurations of the sample liquid aspirating and
dispensing probe means at various stages in the operation of the
sample liquids analysis system of FIG. 1.
Detailed Description of the Invention
Referring now to FIG. 1 of the application drawings, an
automated, successive sample liquids analysis system is depicted
schematically and indicated generally at 10.
The sample liquids analysis system 10 comprises sample
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liquid supply means as indicated generally at 12, immiscible
isolation liquid supply and reservoir means as indicated
generally at 14 and 16, respectively, rinse liquid supply means
as indicated generally at 18, buffer-diluent liquid supply means
5 as indicated generally at 20, sample liquid aspirating and
dispensing probe means as indicated generally at 22, sample
liquid pump means as indicated generally at 24, and sample liquid
reaction and analysis means as indicated generally at 26,
respectively. In addition, reagent and/or substrate liquids)
supply and dispensing means for the addition thereof the sample
liquids in the sample liquid reaction and analysis means for
mixture and reaction therewith as required for sample liquids
analysis, are indicated generally at 28; while supply means for
an agent or agents) as may be required in addition to the
reagent and/or substrate liquids) for sample liquids reaction
and analysis are depicted schematically and indicated generally
at 29 in FIG. 1.
As generally described, it will be readily understood by
those skilled in the automated sample liquids analysis art that
the sample liquids analysis system 10 is operable to the
successively supply, react and quantitively analyze each of a
series of sample liquids in turn with regard to one or more
analytes of interest contained therein; with a major emphasis
regarding system 10 being on the reduction of sample liquid
carryover, i.e. the contamination of a succeeding sample liquid
by the residue of a preceding sample liquid, to heretofore
virtually unattainable, ultra low level commensurate with the
exceedingly stringent accuracy requirements of highly
sophisticated and specialized contemporary clinical chemistries,
for example those involved in non-isotopic immunoassays on human
blood sera.
As more specifically described, sample liquid means 12
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preferably take the general form of those disclosed in each of
United States Patents 4,099,921, 4,1l5,861 and 4,l68,955,
respectively for "Clinical Analyzer" issued July 11, 1978,
November 7, 1978 and September 25, l979 to Robert W. Allington,
and assigned to Instrumentation Specialities Company.
To the above effect, the sample liquids supply means 12
comprise a plurality of like sample liquid receptacles 30, for
example seventy-eight receptacles in groups in a plurality of
moveable shuttles, one of which is shown at 32 in FIG. 1. The
shuttles 32 are in turn supported in and moveable by a shuttle
support mechanism as indicated at 34, driven in turn by electric
drive motor means as indicated schematically at 35 in FIG. 1;
with the mechanism 34 operating to support and periodically move
the shuttles 32 in such manner that the sample liquid receptacles
30, each of which contains a quantity of a sample liquid to be
analyzed as indicated at 36 in FIG. 1, are indexed in turn to a
sample liquid offtake station relative to probe means 22, and
retained thereat for precisely the same period of time for the
aspiration of precisely the same volume of sample liquid
therefrom by the probe means 22 in each instance.
The isolation liquid supply means 14 comprise a container
38 of an appropriate isolation liquid as indicated at 40, and
which is immiscible with the sample liquids 36. Readily
compressible isolation liquid supply conduits 42 and 44, which
branch as indicated at 45, respectively extend as shown in FIG.
1 from container 38 to isolation liquid reservoir means 16 and
probe means 22; and pump means, for example peristaltic pumps as
schematically indicated at 46 and 48, and which are particularly
suitable for precise isolation liquid pumping at low flow rates
as discussed in greater detail hereinbelow, are respectively
operatively formed as shown with the relevant portions of
compressible isolation liquid supply conduits 42 and 44. The
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peristaltic pumps 46 and 48 are driven in turn as indicated in
FIG. 1 by electric drive motor means as schematically indicated
at 47 and 49; and are operable when so driven to supply the
isolation liquid 40 in respectively precisely controlled
quantities, along those conduits from isolation liquid supply
container 38 to isolation liquid inlets 51 and 53 of the
isolation liquid reservoir means 16 and probe means 22,
respectively.
Although by now believed to be well understood by those
skilled in this art, it is here reiterated to insure completeness
of this disclosure that for use, for example, with essentially
aqueous sample liquids 36, and an active component of probe means
22 of an appropriately hydrophobic material, for example Teflon
as described in detail hereinbelow, the isolation liquid 40 would
be constituted, for example, by an appropriately hydrophobic
fluorinated or per-fluorinated hydrocarbon liquid, or "oil" as
the same has come to be termed in the sample liquids analysis
art, which is preferentially attracted to and selectively "wets"
that active probe means component to the substantial exclusion of
the essentially aqueous sample liquids 36, which are immiscible
therewith; thereby substantially preventing the adherence of
sample liquid residue to that active probe component. This in
turn minimizes sample liquid carryover on the active probe means
component, with attendant increase in the accuracy of the sample
liquids analysis results. This phenomenon of selective
wettability, and the application thereof to sample liquids
analysis for minimization of sample liquid carryover through use
of an appropriate isolation liquid, is disclosed in some detail
in each of United States Patent 4, 602, 995 issued July 29, 1986 to
Michael M. Cassaday, et al, for "Liquid Level Adjusting And
Filtering Device," United States Patent 4,515,753 issued May 7,
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1985 to John L. Smith, Ph.D, et al, for "Integral Reagent
Dispenser", and United States Patent 4,678,641 issued July 7,
1987 to Michael M. Cassaday, et al, for "Isolation Liquid Layer
Retention Device", all assigned to Technicon Instruments
Corporation of Tarrytown, New York.
The isolation liquid reservoir means 16 comprise an open
topped, generally cylindrical reservoir body member 50 fabricated
for example from an appropriately hydrophobic plastic material by
molding, which is supplied as shown in FIG. 1 at inlet 51 at the
bottom of the body member with isolation liquid 40 from container
38 by peristaltic pump 46 via supply conduit 42 as discussed
hereinabove. An enlarged liquid overflow chamber 52 is formed as
shown at the top of the reservoir body member 50, and comprises
a drain conduit 54 extending downwardly therefrom as indicated to
waste; it being noted that the level 56 of the upper end of the
drain conduit 54 is coincident with the level 58 of the top of
the reservoir body member 50, whereby the liquid level in the
reservoir means 16 will be maintained coincident therewith, with
any excess liquid flowing therefrom to waste via drain conduit
54.
The rinse liquid supply means 18 comprise a container 60
of any suitable rinse liquid, for example distilled water, as
indicated at 62 in FIG. 1. Rinse liquid supply pump and pump
drive means are indicated generally at 64, and comprise
pressurized air and vacuum supply conduits 66 and 68 which
respectively extend as shown from non-illustrated sources thereof
to the rotatable body member 70 of a three-way valve 72,
including valve passage 74. Rotatable valve body member 70 is
driven as shown by electric drive motor means, for example a
solenoid, as indicated schematically at 75 in FIG. 1.
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A diaphragm pump is indicated at 76, and includes a
pumping chamber 78 divided as shown by a diaphragm 80; and a
conduit 82 extends as shown in FIG. 1 to connect valve passage 74
of valve 72 with one side of pumping chamber 78.
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A two-way rinse liquid supply valve is indicated at 84, and
includes a rotatable valve body member 86 having a valve
passage 88 extending therethrough. Valve body member is
driven as shown by electric drive motor means, again for
example a solenoid, as indicated at 89. A conduit 90
extends as shown to connect the other side of pumping
chamber 78 with one side of rinse supply valve 84. A
conduit 92 branches as shown from conduit 90 to extend into
the supply of rinse liquid 62 in container 60; while a
flexible conduit 94 extends as shown to connect the other
side of valve 84 to the rinse liquid inlet 96 of the probe
means 22. Check valves as indicated at 98 and 99 are
provided in conduits 90 and 92 to restrict rinse liquid flow
therein to the indicated directions; while conduit 90
comprises a flow restrictor tube section 91 which restricts
rinse liquid flow therethrough to levels which will not
degrade the effectiveness of the isolation liquid in
minimizing sample liquid carryover in the probe means 22 as
discussed in greater detail hereinbelow.
For operation of the rinse liquid supply means 18
to supply rinse liquid 62 from container 60 to the rinse
liquid inlet 96 of the probe means 22, and with the body
member 86 of two-way valve 84 rotated to the "open" position
thereof of FIG. 1 to connect conduits 90 and 94, it will be
clear that cycling of the rotatable valve body member 70 of
three-way valve 72 between the depicted position thereof
wherein valve passage 74 connects conduits 66 and 82, and
the non-illustrated position thereof wherein passage 74
connects conduits 68 and 82, respectively, will drive pump
diaphragm 80 to pump the rinse liquid 62 from container 60
via conduits 92, 90 and 94 for supply to the rinse liquid
inlet 96 of the probe means 22.
The buffer-diluent liquid supply means 20 comprise
an open-topped container 100 of the buffer-diluent liquid,
for example distilled water, as indicated at 1O1 in FIG. 1.
For certain applications of the analysis system 10 of our
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invention, as dictated in part by the volumes of the sample
liquids 36 to be aspirated by the probe means 22, the
buffer-diluent 1O1 may include a predetermined quantity by
volume, for example 20$, of an appropriate surfactant, for
example that readily available under the Trademark "Triton
X-100," which operates in conjunction with the isolation
liquid 40 and the rinse liquid 62 to even further reduce
sample liquids carryover to the requisite ultra low levels
as discussed in greater detail hereinbelow.
With reference now to FIGS. 1, 2 and 3 of the
application drawings for more detailed description of the
probe means 22, the same will be seen to comprise a
generally cylindrical body member 1O2 having a stepped,
generally axial bore 1O3 extending therethrough, and
comprising axially aligned bore sections 1O4, 1O6 and 1O8 as
best seen in FIG. 3. Bore section 1O4 is threaded as
indicated at 11O almost to the inner end thereof, leaving an
unthreaded bore section 1l1 of relatively small axial extent
at that inner bore end.
The active probe component is indicated generally
at 112 in FIG. 3, and comprises a generally pipette-like
body member I14 having a tubular upper body portion 116
which smoothly transitions or "necks down" as shown at 118
to a lower tubular body portion 12O which extends from the
probe body member 1O2 well below the lower surface 123
thereof to terminate in an open tip 122. This
configuration of the probe component 112 of course provides
for a greater probe component volume per unit length for
upper probe body portion 116 than for lower probe body
portion 12O; and, for a constant liquid flow rate into the
probe component 112 through open tip I22, will in turn
provide for a lower liquid flow velocity through the upper
probe body portion 116 than through the lower probe body
portion 12O.
The active probe component 112 is operatively
disposed in the body member bore 1O3 concentrically thereof,
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with the outer wall of upper probe component body portion
116 being in firm surface contact with the wall of bore
section 1O6 to prevent radial movement of the probe
component 112 relative to probe body member 102; and the
probe component 112 extends as shown through body member
bore section 1O8 with wall clearance to provide an annulus
as indicated at 121 therebetween to completely surround the
relevant wall surfaces of the upper probe component body
portion 116 which extends therethrough.
A length of tubing of a material of appropriate
strength characteristics is indicated at 125 in FIG. 3, and
is disposed as shown, for example by press-fitting, in body
member bore portion 1O8 to extend therefrom and surround
upper probe component portion 116, both within annulus 121
and for some distance below the lower surface 123 of probe
body member 1O2, essentially for preventing excessive radial
movement of the relevant portion of the active probe
component 112 relative to the body member 1O2, and to
provide some measure of protection against impact damage to '
the same.
A generally radially, downwardly extending stepped
bore is indicated at 127 in FIG. 3, and extends as shown
through the probe body member 102 into fluid flow
communication with the annulus 121; and the end portion of
isolation liquid supply conduit 44 extends thereinto as
shown, and is retained therein in any appropriate manner,
for example by simple press-fitting, to thus place conduit
44 and annulus 121 in isolation liquid flow communication.
A hex nut is indicated at 124 in FIG. 3, and is
threaded as shown at 126 for the screwing thereof into the
complementally threaded probe body member bore portion 1O4.
The hex nut 124 comprises a stepped bore 128 extending
centrally thereof; and it will be clear that upon tightening
of the hex nut 124 into the probe body member 1O2, the bores
128 and 1O3 will be in alignment as shown. Stepped hex nut
bore 128 incudes upper and lower portions 13O and 132, with
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the former being larger than the latter; and the inner end
of the hex nut 124 includes a relatively small unthreaded
portion as indicated at 134 in FIG. 3.
For use, for example, with essentially aqueous
sample liquids 36 and a hydrophobic isolation liquid 40 as
discussed hereinabove, it may be understood that active
probe component 112 is preferably fabricated, as by
drawings, from an appropriate hydrophobic plastic material,
for example essentially rigid Teflon; while, for a11
applications, probe body member 1O2 and hex nut 124 are
preferably machines from a clear acrylic material, and
tubing length 125 cut to an appropriate length from a piece
of stainless steel tubing of suitable diameter.
FIG. 3 makes clear that the, rinse liquid supply
conduit 94 extend through hex nut bore 128, and that the
tubing wall is in firm surface contact with the wall of
lower hex nut bore portion 132 to prevent radial movement
therebetween; with conduit 94 terminating as shown in a
flared end 140 within the unthreaded bore section portion
111 of probe member bore section 1O4. In like manner, upper
probe component body portion 116, which is of the same inner
and outer diameters as rinse supply conduit 94, also
terminates in a flared end 142 in bore section portion 111;
with flared ends 14O and 142 of essentially the same
diameter.
Assembly of the probe means 22 is readily
accomplished by the simple press-fitting of tubular length
125 into probe means body member bore section 1O8 to the
position thereof depicted in FIG. 3; the simple insertion
and movement of, active probe component 112 into and through
the probe body memeber bore 1O3 from above the body member
1O2 until the component 112 comes to rest in the depicted
position thereof with the flared component end 142 in firm
contact with the lower surface 144 of bore section 1O4; the
simple insertion and movement of rinse liquid supply conduit
94 into and through the hex nut bore 128 from below until
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the conduit comes to rest in the depicted position thereof
with the flared conduit end 14O in firm contact with the
bottom surface 146 of the hex nut 124; and the equally
simple insertion and tightening of the hex nut 124 into the
threaded body member bore section 1O4 to very firmly press
the flared probe component and rinse supply conduit flared
ends 142 and '.40 together between opposed bore section and
hex nut surfaces 144 and 146 as depicted in FIG. 3 to form
an extremely fluid-tight juncture, or pressure fitting
therebetween, and place the same in unrestricted fluid flow
communication. The end portion of isolation liquid supply
conduit 44 is then simply press-fitted into probe body
member bore 127 to the position thereof depicted inFIG. 3 to
complete the assembly of the probe means 22.
Electromechanically operable probe means drive
means, including appropriate electric drive motor means, are
indicated schematically at 148 in FIG. 3; and are
mechanically connected as indicated by the dashed line to
the probe means body member 1O2, and operable, in manner well
understood by those skilled in this art, to index probe
means 22 between respective operable positions thereof
relative to sample liquid supply means 12, isolation liquid
supply means 16, buffer-diluent supply means 20 and, if
required, agents) supply means 29, attendant the sample
liquids analysis process, a11 as described in greater detail
hereinbelow.
In the manner of buffer-diluent liquid supply
means 20, the reaction agents) supply means 29 comprise an
open-topped container 15O of such agents) as indicated at
152. For use, for example, of the sample liquids analysis
system 10 in the performance of non-isotopic heterogeneous
immunoassays on sample liquids 36 as constituted by human
blood sera, a representative agent 152 in question would be
magnetic particles, or magnetic solid phase, in suspension
in an appropriate buffer-diluent liquid as discussed
hereinbelow.
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The sample liquid reaction and analysis means 26
preferably take the form of those disclosed in United States
Patent 4,357,30l issued November 2, 1982 to Michael M. Cassaday,
et al, for "Reaction Cuvette," and assigned to Technicon
5 Instruments Corporation, Tarrytown, New York. To that effect,
the reaction and analysis means 26 comprise a circular reaction
tray as schematically indicated at 154 in FIG. 1 and a circular
array of individual, open-topped cup-like containers, or reaction
cuvettes, one of which is indicated at 156, supported adjacent
10 the outer periphery thereof, and respectively including exposed,
radially aligned transparent cuvette wall sections as indicated
at 157 and 159. The reaction tray 154 and cuvettes are
fabricated by molding from an appropriately chemically inert
plastic material; and each of the reaction cuvettes 156 comprises
15 a bottom surface 158 of a hydrophillic material having a
plurality of upwardly extending ridges or projections as
indicated at 160 formed thereon, and which function as described
in detail in United States Patent 4,357,301 to penetrate a film
of the immiscible isolation liquid 40 which encapsulates the
sample liquids 36 upon the dispensing thereof into cuvettes 156
by probe means 22 to render the same physically accessible for
mixture and reactions) as required with sample liquids analysis
reagents) and/or agents) in the cuvettes. The reaction tray
154 indexed by intermittent rotation, which may be sequentially
bi-directional, by electromechanical tray drive means, including
an electrical stepping motor as indicated schematically indicated
at 162 in FIG. 1, to present the reaction cuvettes in turn to
respective stations, for the introduction of those liquids to the
cuvette, and appropriate reactions therebetween; and finally
therefrom to a sample liquids analysis or "read-out" station
whereat sample liquids analysis means, for example an operatively
associated colorimeter as schematically indicated at 164 in
FIG. 1, are operable to automatically analyze the thusly reacted
sample liquids, one of which is indicated at 165 FTG. 1, with
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regard to the analyte(s) of interest through the transparent
cuvette wall sections 157 and 159. Operation of an automated
sample liquids analysis system through use of sample liquids
reaction and analysis means 26 as described is disclosed in
detail in United States Patent 4,629,703.
The sample liquids pump means 24 preferably take the form
of a very precisely operable syringe pump as indicated at 168 in
FIG. 1, and which is connected as shown to rinse liquid supply
conduit 94 by a branch conduit 170. Syringe pump is driven by an
electric drive motor as schematically indicated at 172; and it
will be clear that with rinse liquid supply valve rotated to the
non-illustrated "closed" position thereof, downward movement of
the syringe pump piston 174 will be operable to aspirate sample
liquids 36 in very precisely predetermined quantities through the
open tip 122 of probe component 112 (FIG. 3) into the probe
component via the reduced pressure created thereby in the rinse
liquid supply conduit 94.
Reagent and/or substrate liquids supply means 28 may take
any form appropriate to the dispensing of the same into the
reaction cuvettes 156 at the requests) dispensing stations) as
described hereinabove for mixing and reaction with the sample
liquids 36 within the cuvettes 156 as required for sample liquids
analyses. As such, these supply means may, for example, take the
form of appropriately refrigerated trays ar other support
mechanisms of reagent and substrate liquids containers, for the
reagent liquids for example the integral dispensers as disclosed
in United States Patent 4,515,753, each with operatively
associated dispensing probe means as disclosed in United States
Patent 4,121,466, and respectively operable to dispense and/or
substrate liquids) therefrom as required into the reaction
cuvettes at the dispensing stations therefor of the reaction tray
154 as described hereinabove. The required electromechanical
drive means for these operations of course include electric drive
motor means as schematically indicated at 177 in FIG. 1.
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FIG. 4 schematically depicts a representative control
system for the automated sample liquids analysis system 10; and,
to that effect, will be seen to include a system controller as
indicated at 178 and taking, for example, the form of an
appropriately programmable microprocessor device or "computer" as
the same are more commonly termed. System controller 178 is
electrically connected as indicated by lines 180, 182, 184 and
186 to probe means drive motor 148, sample supply shuttle means
drive motor 35, sample reaction tray drive means drive motor 162
and sample syringe pump drive motor 172, respectively; and system
controller 178 is further electrically connected as indicated by
lines 188, 190, 192 and 194 to rinse liquid control valve drive
motor 89, rinse liquid pump control valve drive motor 75, and
peristaltic pump drive motors 47 and 49, which may be combined
into one drive motor, respectively. In addition, system
controller 178 is electrically connected as indicated by line 196
to colorimeter 164, and as indicated by line 198 to reagent
and/or substrate liquids supply and dispensing means drive
motors) 177; and it will thus be immediately clear to those
skilled in this art that the respective automated operations and
cycle times of the heretofore described components of the sample
liquids analysis system 10 can be very precisely determined,
coordinated, synchronized and controlled as required by system
programmer 178 through the appropriate programming thereof in
accordance with the specific requirements and parameters of the
analyses to be performed on the sample liquids 36 by the system
10.
Referring again to active probe means component
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112 of FIG. 3, and realizing that dimensions may vary in
accordance with the requirements of particular sample liquid
analysis applications to which the sample liquids analysis
system 10 may be put, it may be understood that, for
representative system applications wherein volume of sample
liquids 36 of 20 ul are to be withdrawn in turn from
successively presented sample liquid receptacles 30 by probe
means 22 for dispensing in turn into reaction cuvettes 156
of sample liquid reaction and analysis means 26 for
successive, automated sample liquids analyses, active probe
component 112 could be of approximately 2.6 inches in
overall length, with upper probe component body portion 116
being of approximately 2.0 inches in length, and lower probe
component body portion 12O being of approximately 0.6 inches
in length, as measured in each instance from approximately
the middle, of the necked down probe component portion 118.
Under these conditions, and with upper probe component body
portion 116 being of approximately 0.06 inches in inner
diameter, and lower probe component body portion 12O being
of approximately 0.02 inches in diameter, volumes of
approximately 75 ul and 5 ul will be provided for the upper
and lower probe component body portions 116 and 12O,
respectively. These representative dimensions will, in any
event, provide probe means 22 with the capability of
effectively and precisely aspirating and dispensing
successive sample liquids 36 of volumes ranging from as
small as 1 ul to as large as ?5 ul, as described in detail
hereinbelow, while insuring with regard to the larger of
those sample liquid volumes that no sample liquid 36 ever
comes into contact with the somewhat irregular, and thus
sample liquid carryover intensive in terms of retention of
sample liquid residue, juncture between upper probe
component body member portion 116 and rinse liquid supply
conduit 94.
For a representative sample liquids analysis
system application of this nature, and referring now to FIG.
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5 of the drawings which depicts the probe means 22
immediately upon the withdrawal thereof from the isolation
liquid reservoir means 16 at the completion of a sample
liquid aspiration, dispensing and active probe means
component cleansing cycle, the active probe component 112
and connected rinse liquid supply conduit 94 will be seen to
be substantially filled with rinse liquid 62, supplied
thereto from rinse liquid reservoir 60 as described in
detail hereinbelow, followed by a segment 2O0 of the
isolation liquid 40 as aspirated by the probe means from the
isolation liquid reservoir 50, again as described in detail
hereinbelow. In addition, the inner wall of the active
probe means component 112 above the isolation liquid segment
2O0, extending upwardly therein at least to the juncture
thereof with the rinse liquid supply conduit 94 if not
highter as depicted, is coated with a thin layer 2O2 of the
isolation liquid 40 (shown as of exaggerated thickness in
FIG. 5 for purposes of clarity of illustration) which
remains therein from previously aspirated isolation liquid
40; while external wall of the probe component body portions
116 and 12O which extend downwardly below the upper end of
annulus 121 are also coated with a thin layer 2O4 of the
isolation liquid 40 (again shown as of exaggerated thickness
as above) which flows downwardly thereover from the annulus
121 under the force of gravity, also as described in detail
hereinbelow.
At this point in the operation of probe means 22,
rinse liquid supply valve 84 has been rotated to the
"closed" position thereof; and it may be understood that
the combination of atmospheric pressure, and capillary
action in the probe component body member 114 as a result of
.liquid surface tension, will be sufficient to retain the
rinse liquid 62 and the isolation liquid segment 200 in the
probe component body member 114 to prevent the flow thereof
from the same under the force of gravity due to the rinse
and isolation liquid "head" in the probe component body
CA 02270151 1999-OS-03
member 114 and rinse liquid supply conduit 94, respectively. For
operation with sample liquids volumes of 20 ul as discussed
hereinabove, it may be understood that a representative volume
for isolation liquid segment 200 would be to ul.
5 With the probe means 22 removed from the isolation liquid
reservoir 50 to expose the open probe tip 122 to the ambient air,
and with rinse liquid supply valve 84 remaining closed, it may be
understood that sample liquid supply pump 168 is operated by
downward movement of pump piston 174 to aspirate a segment 206 of
10 representative volume of 3 ul of ambient air into probe component
l12; and this is followed by the indexing of the probe means 22
and the immersion of the open probe tip 122 in the buffer-diluent
liquid 101 in container 100, and the continued operation of
sample liquid supply pump 168 as described to aspirate a segment
15 208 of the buffer-diluent liquid 101 into the probe component; it
being clear that, although immersion of the open probe tip Z22 in
any liquid for aspiration of necessity includes the immersion of
some portion of lower probe component body member portion 120
therein, such immersion is strictly limited to that lower probe
20 component body member portion. A representative volume for
buffer-diluent liquid segment 208 is 10 ul.
Operation of pump 168 is then discontinued, and the probe
means 22 indexed to immerse the open probe tip 122 in the sample
liquid 36 in the sample liquid receptacle 30 newly indexed by the
shuttle means 32 to the probe sample liquid off-take station;
whereupon sample liquid supply pump 168 is re-activated as
described to aspirate a sample liquid segment 210 of 20 ul volume
into the probe component 112 for merger therewithin with the
buffer-diluent liquid segment 208, as shown in FIG. 6, followed
by discontinuance of the operation of pump 168 and withdrawal of
the probe means 22 from the sample liquid receptacle 30.
FIG. 6, which depicts the operational
CA 02270151 1999-OS-03
21
configuration of the probe means 22 at this point in the
operation of sample liquids analysis system 10 makes clear
that aspiration as described of the respective air, buffer-
diluent liquid and sample liquid segments 2O6, 2O8 and 21O
will displace much of the previously aspirated isolation
liquid segment 200 to the inner walls of the probe component
112, with only thin isolation liquid segments as indicated
at 212 and 214 (again shown as of exaggerated thickness)
remaining between the rinse liquid 62, the air segment 206,
and the merged buffer-diluent and sample liquid segments 2O8
and 21O to separate the same. FIG. 6 also makes clear that
the continued flow of the isolation liquid layer 2O4
downwardly along the outer wall of the relevant portion of
active probe component 112 under the force of gravity as
described will, in accordance with the natural flow
characteristics of that highly viscous liquid, operate to
cover the trailing, insofar as order of aspiration is
concerned, edge of the merged buffer-diluent and sample
liquids segments 2O8 and 21O with a thin layer (again of
exaggerated thickness) 212 of the isolation liquid, thereby
making clear that the merged buffer-diluent and sample
liquids segments 2O8 and 21O effectively encapsulated in the
isolation liquid 40.
With the probe means 22 in the operational
configuration of FIG. 6, the same is then indexed to the
probe dispensing station immediately above the next
available reaction cuvette 156 as has been indexed as
described to that station by rotation of tray 154; and, with
rinse liquid supply valve 84 remainaing closed, sample
liquid supply pump 168 is operated by upward movement of
pump piston 168 to a precisely predetermined extent to pump
a11 of the isolation liquid-encapsulated, merged buffer-
diluent and sample liquid segments 2O8 and 21O from the
probe component 112 into the cuvette 156 through open probe
tip l22, thereby leaving the probe means 22 essentially in
the operational configuration illustrated in FIG. 7 wherein
CA 02270151 1999-OS-03
22
the probe component 112 is again substantially filled with
the rinse liquid 62, with some measure of the isolation
liquid 40 remaining at the probe tip 122 as indicated at
214, and the isolation liquid layers 2O2 and 2O4 at the
respective outer and inner walls of the active probe
component 112 remaining intact, both as also made clear by
FIG. 7. A representative volume of the isolation liquid
dispensed as described by the probe means 22 into the
cuvette 156 with the merged buffer-diluent and sample liquid
segments 208 and 210 is 2 ul, with much of the isolation
liquid remaining in the active probe means component 112
having been further displaced to the inner walls thereof
attendant buffer-diluent and sample liquid dispensing
therefrom as described.
The addition of. the requisite reagents) and/or
substrates) liquids to the thusly dispensed sample liquid
36 in the reaction cuvette 156 by the supply means 28 for
those liquids as heretofore described through appropriate
indexing of the reaction tray 154, the further treatment of
the same as may be required in the reaction cuvette 156. and
the analysis of the thusly reacted and treated sample
liquids 165 (FIG. 1) by the optical sample liquids analysis
means 164 are then automatically accomplished.
Following sample liquid dispensing as described
into the reaction cuvette for analysis, probe means 22 are
indexed to the position thereof immediately over the
isolation liquid reservoir 50 (FIG. 1), and at least that
part of the lower probe member body portion 112 which was
immersed as heretofore described in the sample liquid
container 30 is immersed in the isolation liquid 40 in that
reservoir; whereupon rinse liquid supply valve 84 is
opened, and rinse liquid supply pump ?6 activated to pump
the isolation liquid quantity 214 (FIG. 7), the rinse liquid
62 then present in the active probe component 112 and in
rinse liquid supply conduit 94, plus an appropriate quantity
of the rinse liquid from rinse liquid supply container 62 to
CA 02270151 1999-OS-03
23
and the probe means component 112 as the case may be out of the
open probe component tip 122 into the reservoir 50 against the
direction of aspirated sample liquid flow in the active probe
component 112. This very effectively backflushes the interior
wall of the probe component 112, virtually insuring the removal
of a11 residue of the just-dispensed sample liquid 36 therefrom;
with the thusly pumped rinse liquid, which is of lower specific
gravity than the isolation liquid, simply flowing from the probe
component 112 into the isolation liquid 40 in the reservoir 50,
and rinsing to the top of the latter for flow as indicated as the
rinse liquid layer 53 atop the isolation liquid 40 from reservoir
50 through overflow chamber 52 to waste via drain conduit 54 as
seen in FIG. 1. A representative volume of rinse liquid 40 which
is pumped as described from active probe component 1l2 during
this rinsing cycle is 300 ul.
Rinse liquid supply valve 84 is then closed, and sample
supply pump 168 activated to aspirate the 10 ul segment 200 of
the isolation liquid 40 into the probe component 112 through open
probe tip 122 from the isolation liquid reservoir 50; and the
probe component 112 then removed from the isolation liquid
reservoir 50 to assume the operational configuration thereof of
FIG. 5 for repetition of the sample liquid aspiration and
dispensing cycle as described; with a further coating of the
isolation liquid having been added to the relevant portion of
isolation liquid layer 204 at the exterior wall of the active
probe component 112 by the immersion thereof in the same in the
isolation liquid reservoir 50 as described.
Replenishment of the supply of the isolation liquid 40 in
the isolation liquid reservoir 50, and of the supply thereof to
probe body member - active probe component annulus 121 (FIG. 3),
both to insure that there is always sufficient isolation liquid
in the reservoir 50 to enable the aspiration as described by the
probe means 22 of the isolation liquid segment 200 prior to
buffer-diluent and sample liquids segments aspirations as
CA 02270151 1999-OS-03
24
described, and to insure the continued presence of the isolation
liquid layers 202 and 204 on the respective interior and exterior
walls of the active probe means component 112 attendant a11
operations of the probe means 22, is provided by the periodic
operations of peristaltic pumps 46 and 48 to supply the isolation
liquid 40 via conduits 42 and 44 as heretofore described. These
periodic operations of pumps 46 and 48 may, for example, occur
immediately prior to sample liquid aspiration, and immediately
following sample liquid dispensing, respectively; and a
representative volume of the isolation liquid 40 thusly supplied
per sample liquid aspiration and dispensing cycle of the probe
means 22 is 20 ul.
For use, for representative example, of the sample
liquids analysis system 10 in the automated performance of
heterogeneous immunoassays on human blood sera for determination
of the presence of the pregnancy hormone Beta HCG therein, and
which require the addition of the magnetic particles 152 (FIG. 1)
to the sample and reagent liquids in the reaction cuvette, it may
be understood that immersion of the active probe means component
112 in the isolation liquid reservoir 50 as heretofore described
following dispensing of a sample liquid 36 into a reaction
cuvette 156 would, in turn, be followed only by the pumping of
the rinse liquid 62 from reservoir 60 through the probe component
112 against the direction of aspirated sample liquids flow to
thoroughly back-flush and rinse the same; whereupon the probe
means 22 would be removed from the isolation liquid reservoir 50
without the aspiration of the isolation liquid segment 200, thus
leaving
CA 02270151 1999-OS-03
the probe means component 112 filled with rinse liquid 62,
with rinse liquid supply valve 84 closed. Sample liquid
supply pump 168 is then operated to aspirate a segment 218
of ambient air of representative 3 ul volume through the
open probe tip 122 into probe component 112; and this is
followed by immersion of the probe component 112 as
heretofore described into the liquid-suspended magnetic
par'.-.icles 152 in supply container 15O for the aspiration,
again through operation of sample liquid supply pump 168, of
a segment 22O of the liquid-suspended magnetic particles 152
thereinto in a representative volume of 20 ul. The
operational configuration of the probe means 22 at this
stage in the sample liquids analysis process is depicted in
FIG. 8.
Following the above, the probe means 22 are
indexed to immerse the probe component 122 in a previously
dispensed sample liquid 36 in a reaction cuvette 156 to
which the requisite reagent liquids) have already been
added as indicated at 165 in FIG. 1, and the sample liquid
supply pump 168 again operated to dispense the liquid
suspended magnetic particles segment 22O thereinto for
mixture with the appropriately reacted sample liquid; and it
will be readily understood by those skilled in this art
that, in order to insure that the sample-reagents) liquids
reaction has proceeded as required to completion in the
cuvette 156 of interest prior to the introduction of the
liquid-suspended magnetic particles segment 200 thereto, a
not insubstantial time period, for representative example 20
minutes, may have elapsed between the time that the sample
and reagents) liquids were introduced to the reaction
cuvette 156, and the time at which the liquid-suspended
magnetic particles segment 22O is introduced thereinto. In
accordance with the teachings of the invention, the probe
means 22 and the sample liquids reaction and analysis means
26 do not remain idle during this time period; but rather,
and in accordance with the full random access capabilities
CA 02270151 1999-OS-03
26
of the sample liquids analysis system 10 as set forth in some
detail in United States Patent 4,629,703, remain operational at
full capacity to aspirate, dispense, react, treat and analyze
other and different sample liquids as heretofore described.
Following liquid-suspended magnetic particles dispensing
as described, the now again rinse liquid-filled probe means 22
are indexed from the reaction cuvette 156 of interest and
returned for immersion of the probe means component 122 to the
isolation liquid reservoir 50 for repetition of the probe means
rinse cycle as heretofore described, and the withdrawal of the
probe component 122 therefrom, either with or without the
isolation liquid segment 200 of FIG. 5 depending upon the next
application to which the probe means 22 are to be put, namely
sample liquid or liquid-suspended magnetic particles aspiration.
Although the number of sample liquids analyses that can
be accomplished by the sample liquids analysis system 10 can vary
in accordance with the particular requirements of the same, a
representative operational rate for the system l0 is 120 of such
sample liquids analyses per hour; with a representative cycle
time for the probe means 22 between successive sample liquids
aspirations being approximately 3 seconds.
In addition to the significant advantages with regard to
reduction of sample liquid carryover provided as heretofore
described by the isolation liquid layers 204 and 202 on the
exterior and interior walls of the active probe means component
112, which advantages are by now well known and understood by
those skilled in this art, it will be clear that the sample
liquids analysis system 10 of the invention provides the
additionally significant advantages, again with regard to
reduction of sample liquid carryover, of very thorough rinse of
the same; it having been determined that, under certain sample
liquids analysis conditions, sample liquids residues, for example
in the form of protein molecules as present in human blood sera,
which are extremely "sticky", can and do adhere to the isolation
CA 02270151 1999-OS-03
27
liquid layers at the exterior and interior walls (primarily the
latter) of the active probe component; and, that in the absence
of rinse thereof, can and do contribute to measurable sample
liquid carryover, albeit at very low levels. Forceful rinsing as
described of the isolation liquid layer 202 at the interior wall
of the active probe component 112 by the rinse liquid in the
direction opposite to the direction of aspirated sample liquid
flow to back-flush the same has proven effective to remove
virtually a11 of any such sample liquid residue as may be present
thereon; while the forceful immersion of the relevant portion of
the active probe means component 112 into and through the rinse
liquid layer 55 (FIG. 1) and isolation liquid 40 in the isolation
liquid reservoir 50, and the subsequent forceful withdrawal of
that probe means component portion therethrough following rinse
liquid flow as described, have proven effective to remove
virtually a11 of any such sample liquid residue as may be present
on the isolation liquid layer 204 on the exterior wall of that
relevant probe means component. Too, the virtually constant
presence of the rinse liquid 40 in the active probe means
component 112, both prior and subsequent to sample liquid
aspiration and dispensing as described, of course tends to
further cleanse the isolation liquid layer 202 at the relevant
interior probe component wall portion by picking up sample liquid
residue, if any, therefrom for expulsion from the probe component
112 with the rinse liquid into the isolation liquid reservoir 50
during the probe component rinse cycle.
Additional minimization of sample liquid carryover is
provided in the sample liquids analysis system 10 by the
aspiration of the buffer-diluent liquid segment 208 which, for
the aspiration of sample liquid segments 210 of volume warranting
the same, for example 10 ul or above, contains a
CA 02270151 1999-OS-03
28
reasonably high concentration, for example 20~ by volume, of
an appropriate surfactant as heretofore described; it being
understood that the thusly constituted buffer-diluent
liquids segment 2O8, which merges as heretofore described
with regard to FIG. 6 with the subsequently aspirated sample
liquid segment 21O to place the highest buffer-diluent
liquid concentration at the back or upper end of the thusly
merged liquids segment, operates to very significantly
reduce the overall surface tension of that merged liquids
segment, in particular at the more critical back or upper
end thereof, thereby better retaining the physical integrity
thereof and providing a far more cohesive merged essentially
aqueous liquids segment 2O8 and 21O in the adjacent presence
of the isolation liquid 40 for expulsion as such,
essentially without merged liquids segment break-up and
attendant "loose" sample liquid residue, from the active
probe means component 112 upon segment dispensing as
heretofore described into a reaction cuvette 156. In
addition, the presence of the surfactant in the buffer-
diluent liquid segment 2O8 functions to materially increase
the mobility of the ordinarily not particularly mobile
protein molecules as may be present in the sample liquid
segment 210, and this greatly reduces the non-specific
binding characteristics of those protein molecules, and the
likelihood of the same adhering to the isolation liquid
layer 2O2.
In accordance with a11 of the above, and for use
for example in the automated performance of heterogeneous
immunoassays cn human blood sera samples with regard to the
pregnancy hormone Beta HCG as discussed hereinabove, it may
be understood that the sample liquids analysis system 10 of
the invention has proven effective in tests to date to
consistently meet, or even exceed, the ultra low sample
liquid carryover limit of 5 parts per million of succeeding
sample liquid as required for the validity of the same; and
it will be immediately clear to those skilled in this art
CA 02270151 1999-OS-03
29
that no known automated sample liquids analysis system which
relies on isolation liquid alone for sample liquid carryover
minimization can consistently meet that particularly
stringent standard.
With regard to the probe means 22 of the
invention, ~ se, the same will immediately be seen to also
offer the particularly significant: advantage of providing
for the simple, low cost, and virtually immediate
replacement of the active probe means component 112 in the
event of physical damage thereto as does occasionally occur
due, for example to operator error in the operation of an
automated sample liquids analysis system, with minimal
analysis system down-time, and virtually no adverse effect
upon the requisite fine degree of system calibration, and/or
the accuracy of subsequent system operation. More
specifically, and in the event of damage to active probe
means component 1l2 requiring the replacement thereof, the
system 10 is shut down, hex nut 124 is simply unscrewed and
removed from probe means body member 1O2 without adverse
effect of any nature upon rinse liquid supply conduit 94
which simply remains inserted therein as heretofore shown
and described, the damaged active probe means component 112
simply removed from probe means body member 102 by pushing
the same upwardly from the component bottom until the flared
component end 142 can be freely grasped by the fingers or
appropriate tool within the probe body member bore 1O4 for
simple removal of the component 112 therefrom, a "new" probe
means component 112 simply inserted from the top into the
body member bore 1O3 and pushed therethrough unti-i the
flared component end 142 comes to rest on bore surface 144,
and the hex nut~124, with the rinse liquid supply conduit 94
remaining operatively disposed therein, and absolutely
unchanged with regard tn length, configuration, and
particular liquid flow characteristics, simply re-inserted
into body member bore 1O4 and screwed tightly thereinto to
re-establish the fluid-tight connection between the flared
CA 02270151 1999-OS-03
30
ends 140 and 142 of the rinse liquid supply conduit 94 and
the "new" active probe means component 1l2, and the
requisite communication between the same. This makes clear
that replacement of the active probe means component 112 can
be readily and conveniently accomplished as described
totally without adverse effect upon what is generally termed
the "service loop", i.e. the relevant lengths of rinse
liquid supply conduit 94, and isolation liquid supply
conduit 44, and thus upon the accuracy of subsequent
analysis system performance; with the cost of such
replacement beyond time costs being limited to the cost of
the "new" active probe means component 112 which is, of
course, decidedly minimal, and no time-consuming fine re-
calibration of the sample liquids analysis system 10
required. In accordance with the above, it should be
immediately clear to those skilled in this art that no prior
nrt prob4 means suitable for use in highly sophisticated
automated sample liquids analysis systems of the type here
under discussion can meet these highly demanding
requirements of ease, low cost, minimal system down-time and
virtually non-existent adverse impact upon subsequent system
performance with regard to effective probe means
replacement.
Various changes can of course be made in the
invention as disclosed herein without departing from the
spirit and scope thereof as defined in the appended claims.
