U.S. patent application number 11/009832 was filed with the patent office on 2005-05-19 for reader for conducting assays.
This patent application is currently assigned to Associates of Cape Cod, Inc.. Invention is credited to Dawson, Michael, Elias, Elias R., Fan, Chiko, Novitsky, Thomas J., Richardson, Keith, Shinn, Alan.
Application Number | 20050106746 11/009832 |
Document ID | / |
Family ID | 34576210 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050106746 |
Kind Code |
A1 |
Shinn, Alan ; et
al. |
May 19, 2005 |
Reader for conducting assays
Abstract
An analytical device that can be used to conveniently and
accurately assay plural vessels. In one exemplary embodiment, a
pair of LED sources provides illumination through a pair of radial
waveguides to plural vessels arranged in a pair of substantially
concentric and circular rows about the LED sources. A light pipe
receives light transmitted through a vessel from each radial
waveguide and reflects the received light downward to a single
printed circuit board that contains a photodiode for each light
pipe, as well as processing circuitry. The first LED source/radial
waveguide optical is used to confirm the presence of a vessel, and
the second is used to perform, e.g., turbidometric and/or
colorimetric assays upon an analyte within the vessel. The vessel
is incubated in a vessel support that includes a heat conducting
base and a heat insulating cover. Heat is supplied by a DC
heater.
Inventors: |
Shinn, Alan; (Berkeley,
CA) ; Fan, Chiko; (San Jose, CA) ; Elias,
Elias R.; (Milton, MA) ; Novitsky, Thomas J.;
(Teaticket, MA) ; Dawson, Michael; (East Falmouth,
MA) ; Richardson, Keith; (Woods Hole, MA) |
Correspondence
Address: |
LOWRIE, LANDO & ANASTASI
RIVERFRONT OFFICE
ONE MAIN STREET, ELEVENTH FLOOR
CAMBRIDGE
MA
02142
US
|
Assignee: |
Associates of Cape Cod,
Inc.
East Falmouth
MA
|
Family ID: |
34576210 |
Appl. No.: |
11/009832 |
Filed: |
December 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11009832 |
Dec 10, 2004 |
|
|
|
09721973 |
Nov 27, 2000 |
|
|
|
60167618 |
Nov 26, 1999 |
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Current U.S.
Class: |
436/164 ;
422/82.05 |
Current CPC
Class: |
Y10T 436/11 20150115;
G01N 21/532 20130101; G01N 21/272 20130101; G01N 21/253 20130101;
G01N 21/51 20130101 |
Class at
Publication: |
436/164 ;
422/082.05 |
International
Class: |
G01N 021/00 |
Claims
1-83. (canceled).
84. An assay device comprising: a light source; a plurality of
vessel wells in which at least one well of the plurality of vessel
wells is configured to receive light from the light source; and a
first light sensor configured to detect a signal from the at least
one well of the plurality of vessel wells configured to receive
light from the light source.
85. The assay device of claim 84 in which the light source is a
LED.
86. The assay device of claim 84 in which the at least one light
sensor is a photodiode.
87. The assay device of claim 84 further comprising an optical
filter between the light source and the at least one well of the
plurality of vessel wells that is configured to receive light from
the light source.
88. The assay device of claim 84 further comprising a second light
sensor configured to receive light from the at least one of the
plurality of vessel wells configured to receive light from the
light source.
89. The assay device of claim 88 in which the first and second
light sensors are located on a single printed circuit board.
90. The assay device of claim 84 further comprising at least one
light pipe configured to direct light from the at least one well of
the plurality of vessel wells configured to receive light from the
light source.
91. An assay device comprising: a light source; a plurality of
vessels wells in which at least one well of the plurality of vessel
wells is configured to receive light from the light source; a
plurality of light sensors, wherein at least one of the plurality
of light sensors is configured to detect a light signal from the at
least one well of the plurality of vessel wells configured to
receive light from the light source.
92. The assay device of claim 91 in which the light source is a
LED.
93. The assay device of claim 91 in which the at least one of the
plurality of light sensors configured to detect a signal from the
at least one well of the plurality of vessel wells is a
photodiode.
94. The assay device of claim 91 further comprising an optical
filter between the light source and the at least one well of the
plurality of vessel wells that is configured to receive light from
the light source.
95. The assay device of claim 91 in which the plurality of light
sensors are located on a single printed circuit board.
96. The assay device of claim 91 further comprising a processor
configured to control the light source and the plurality of light
sensors.
97. The assay device of claim 91 further comprising at least one
light pipe configured to direct light from the at least one well of
the plurality of vessel wells that is configured to receive light
from the light source.
98. An assay device comprising: a plurality of vessel wells each
configured to receive light; a light source configured to provide
light to a single well of the plurality of vessel wells; and a
light sensor configured to receive a light signal from the single
well.
99. The assay device of claim 98 in which the light source is a
LED.
100. The assay device of claim 98 in which the light sensor is a
photodiode.
101. The assay device of claim 98 further comprising an optical
filter between the light source and the single well.
102. The assay device of claim 98 further comprising a second light
sensor configured to receive light from the single well.
103. The assay device of claim 102 in which the first and second
light sensors are located on a single printed circuit board.
104. The assay device of claim 98 further comprising at least one
light pipe configured to direct light from the single well of the
plurality of vessel wells.
105. An assay device comprising: a light source; a vessel well
configured to receive light from the light source; and two or more
light sensors located on a single printed circuit board, wherein at
least one of the two or more light sensors is configured to receive
a light signal from the vessel well.
106. The assay device of claim 105 in which the light source is a
LED.
107. The assay device of claim 105 in which at least one of the two
or more light sensors is a photodiode.
108. The assay device of claim 105 further comprising an optical
filter between the light source and the vessel well.
109. The assay device of claim 105 further comprising at least one
light pipe configured to direct light from the vessel well
configured to receive light from the light source.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application No. 60/167,618 filed Nov. 26, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention is directed towards the Pyros Kinetix reader
for conducting assays. More specifically, this invention is
directed to providing an analytical device that, in one embodiment,
conveniently and accurately assays both turbidity and chromogenic
reactions in plural vessels.
[0004] 2. Discussion of the Background
[0005] Optical techniques are commonly used to transduce a number
of different chemical and biological parameters. Among many
thousand such examples, turbidometric measurements can be used to
bioassay and/or bioscreen for the presence of endotoxin using
Limulus amebocyte lysate (LAL) such as PYROTELL-T (Associates of
Cape Cod, Falmouth, Mass.). Similarly, chromogenic measurements can
be used to bioassay and/or bioscreen for the presence of endotoxin
using the POLYCHROME chromogenic formulation of LAL (Associates of
Cape Cod, Falmouth, Mass.), which releases a yellow chromophore
when exposed to endotoxin.
[0006] Many different instruments have been described that use
optical techniques to transduce these and other such biological
parameters. For example, Hoyt (U.S. Pat. No. 4,936,682) describes
an instrument for measuring the light absorption characteristics of
a plurality of samples arranged in a substantially circular pattern
about a single incandescent light source. Incandescent light
sources are however only suitable for performing certain types of
assays since their emission intensity is primarily in the IR and
long wavelength portion of the visible spectrum. Moreover,
incandescent light sources require intensity adjustments to
maintain a relatively constant emission flux, have limited
operational lifetimes, and, as a consequence of resistive heating
of the filament, dissipate large amounts of heat that often
complicate temperature control in incubators. Finally, since
incandescent sources require relatively large amounts of power,
they are commonly driven by high power AC sources such as line
sources and microcontroller-based modulation of incandescent source
intensity is relatively difficult to implement. Shirasawa (U.S.
Pat. No. 5,337,139) describes a multichannel optical measuring
system which uses multiple branches of a quartz optical fiber to
project light from mercury or xenon lamps at glass cuvettes that
contain biological cell samples in order to perform fluorometric
measurements. Shirasawa (U.S. Pat. No. 5,337,139) also describes
that a light emitting diode (LED)/photodiode pair can be associated
with each glass cuvette to generate a signal related to the
intensity of transmitted light through the cuvette. Mioduski (U.S.
Pat. No. 3,882,318) describes a reaction block configured to hold a
reaction chamber where a specimen and a test reagent are mixed. The
reaction block has two optical paths therethrough, one for
conducting a transmittance measurement of the specimen/test reagent
mixture, and the other to detect the presence of a reaction chamber
within the block. Each reaction block has an associated printed
circuit board for detecting light output from both paths. Noeller
(U.S. Pat. No. 4,784,947) describes a method for photographically
recording fluorometric and nephelometric analyses performed using a
photo-flash or a strobe light photon source. As both the light
transduction and light generation described by Noeller (U.S. Pat.
No. 4,784,947) only occurs at discrete times, continuous monitoring
and automated data analysis is not possible.
[0007] The disclosure of each of the above-noted patents is
incorporated herein by reference.
SUMMARY OF THE INVENTION
[0008] Accordingly, one object of this invention is to provide a
novel method and device for conducting assays.
[0009] Another object of this invention is to provide a novel
method and device that, in one embodiment, allows a user to
simultaneously assay both turbidity and chromogenic reactions in
plural vessels.
[0010] Another object of this invention is to provide a novel
method and device that, in one embodiment, allows a user to conduct
several assays simultaneously, each assay not necessarily having a
same start time.
[0011] Another object of this invention is to provide a novel
method and device that, in one embodiment, reduces device component
and assembly costs, minimizes the size of the device, makes repair
easier.
[0012] Another object of this invention is to provide a novel
method and device that, in one embodiment, allows a user to
incubate plural assays in plural vessels using a minimum of power
while maintaining a desired incubation temperature.
[0013] These and other objects of the invention can be realized by
using a PYROS KINETIX READER and similar devices. Such devices can
include, according to one embodiment, a single LED source providing
illumination to plural vessels through a radial waveguide. Some
embodiments can include two LED sources in a single device, each
illuminating plural vessels along a different radial waveguide.
Some embodiments can include more than two LED sources in a single
device. Other embodiments can include one or more radial waveguides
for presenting emitted light to the plural vessels at a high
intensity. Other embodiments can present emitted light along two
radial waveguides through a single vessel, the first radial
waveguide being used to detect a presence of the vessel and the
second radial waveguide being used to transduce an optical property
of an analyte within the vessel. Some embodiments include
modulation of the emission intensity of the one or more LED
sources, this modulation being, e.g., a step function. In some
embodiments, this modulation is microprocessor-based. In other
embodiments, this modulation is mechanical, analog, or otherwise
electronically implemented. In some embodiments, the LED source(s)
emit substantially at 470 nm.+-.30 nm. In some embodiments, one or
more optical filters is placed along an optical path that passes
through the vessel.
[0014] Other embodiments of such devices can include the vessels
arranged in a substantially circular geometry around the LED light
source(s). Other embodiments may include plural groups of two or
more vessels at two or more different radii about a center. Another
embodiment may include two groups of 48 vessels at two different
radii about the center. In some embodiments, an LED is positioned
at the center point. In some embodiments, one or more optical
waveguides is used to substantially evenly distribute light from
one or more LED's to several vessels. In some embodiments, a lens
is used to position a virtual image of one or more LED's at the
center. In some embodiments, multiple LED's are vertically
staggered along a line passing through the center.
[0015] Other embodiments of such devices can include a single
printed circuit board containing plural phototransducers. Some
embodiments may include a single printed board having all
phototransducers. Some embodiments provide plural vessels in a same
plane, and a plane of such a single printed circuit board being
substantially parallel to such a plane. Some embodiments provide a
plane of such a single printed circuit board below at least one
vessel. In some embodiments, a light pipe is used to guide light
transmitted along an optical path through a vessel to such a single
printed circuit board.
[0016] Other embodiments of such devices can include a
multicomponent support for the vessels, a first component being
chosen to conduct heat for incubating one or more vessels at a set
temperature. In some embodiments, another component is chosen to
thermally insulate the first component and reduce power demands of
the device. In some embodiments, the other component is lighter
that the first component and reduces the net weight of the
device.
[0017] Other embodiments of such devices can include a
precalibrated temperature transducer that reduces calibration
demands for operating such a device.
[0018] The aforementioned and other objects of the invention can
also be realized using methods that are simple to implement upon
the PYROS KINETIX READER and other similar devices. A method for
performing assays can involve generating light using a LED,
radially guiding a portion of the generated light, transmitting a
portion of the guided light through a plurality of vessels, and
transducing a portion of the transmitted light to assay a sample.
In some embodiments, a portion of the generated light can be
transmitted through a side or a bottom portion of the plurality of
vessels and used to detect the presence of the plurality of
vessels. In other embodiments, a portion of the transmitted light
can be reflected using a light pipe. In some embodiments, a portion
of the generated light can be diverged. In other embodiments, the
generated light can be modulated to yield a background
measurement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same become better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0020] FIGS. 1A and 1B illustrate, respectively, a top view and a
side view of an exemplary optical system according to the present
invention;
[0021] FIGS. 2A, 2B, and 2C illustrate a side view of various light
paths through an exemplary optical system without a sample holding
vessel present, with a sample holding vessel present, and with a
sample holding vessel present at an increased magnification;
[0022] FIGS. 3A and 3B illustrate, respectively, a top view and a
side view of an exemplary embodiment of the optical system that
includes a central light source with multiple wells;
[0023] FIGS. 4A and 4B illustrate, respectively, a top view and a
side view of a second exemplary embodiment of the radial light
guide 30;
[0024] FIGS. 5A and 5B illustrate, respectively, a top view and a
side view of an exemplary embodiment of the optical system that
includes the second exemplary embodiment of the radial light guide
30;
[0025] FIGS. 6A and 6B illustrate, respectively, a top view and a
side view of a third exemplary embodiment of the radial light guide
30;
[0026] FIGS. 7A and 7B illustrate, respectively, a top view and a
side view of an exemplary embodiment of the optical system that
includes the third exemplary embodiment of the radial light guide
30;
[0027] FIG. 8 illustrates a schematic of a top view of an exemplary
arrangement of a optical system that includes the third exemplary
embodiment of the radial light guide 30;
[0028] FIG. 9 illustrates an exemplary vessel support 80 containing
two concentric circular rows of wells 45, as well as various
components to be entirely or partially inserted into the exemplary
vessel support 80;
[0029] FIG. 10 illustrates an exploded view of an assay device
according to the present invention;
[0030] FIG. 11 illustrates a wireframe view of an exemplary
assembled assay device;
[0031] FIG. 12 illustrates an exemplary electronics block diagram
of an assay device;
[0032] FIGS. 13A-C illustrate a top view in the absence of an
analyte holding vessel 40, a top view in the presence of an analyte
holding vessel 40, and a side view in the presence of an analyte
holding vessel 40 that uses an exemplary side wall tube detection
scheme with a single radial light guide 30;
[0033] FIG. 14 illustrates an exemplary process loop for monitoring
and controlling the incubation temperature according to the present
invention;
[0034] FIG. 15 illustrates a process flow for an exemplary on/off
modulation of the light output by LED source 1 for background
correction; and
[0035] FIG. 16 illustrates an exemplary computer system 801 that
can form an external control/record processor in an embodiment of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Referring now to the drawings, wherein like reference
numerals designate identical or corresponding parts throughout the
several views, and more particularly to FIG. 1 thereof, which
illustrates an exemplary optical system according to the present
invention. The illustrated optical system generates light, radially
guides it to one or more vessels containing an analyte, transmits
the light through the vessel and/or the analyte, and then pipes the
light to one or more light transducers where it is transduced. As
used herein, radial guiding refers to the transmission of light to
plural vessels along plural optical paths, wherein the
transmittance along the various paths is substantially equal. This
situation is possible to implement using a circular (or arcular)
waveguide with a source located at the center, hence giving rise to
the term "radial guiding."
[0037] In FIGS. 1A and 1B, LED source 1 generates and emits
photons, and can also optionally serve to collimate and/or focus
the generated photons. Examples of commercially available LED's
that can form the LED source 1 are the Nichia P/N NSPB500S, the
Kingbright P/N L934MBC, and the Hewlett-Packard P/N HLMP-CB16.
LED's generate relatively large photon fluxes over relatively
narrow bandwidths, especially relative to incandescent sources
which emit over a very large bandwidth. In one embodiment, LED
source 1 can generate photons centered around substantially 470 nm
with a bandwidth .+-.30 nm, although those skilled in the art can
increase or decrease the center wavelength and the bandwidth
surrounding it to provide different responses. Naturally, plural
LED's may be used along with multiple versions of the illustrated
optical system in the same assay device. In such a case, LED's with
different center wavelengths and/or intensities may be selected to,
e.g., provide broader dynamic range for assays, allow dual
wavelength assays to, e.g., increase sensitivity and/or allow a
user to use plural chromophores and/or obtain better background
correction information.
[0038] Also illustrated in FIG. 1B is an optical filter 2 between
the LED source 1 and the radial waveguide 30. The filter 2 is
optional; since a LED emission spectrum is already relatively
narrowband, it is often not necessary to include filter 2, which
further lowers the cost and power requirements of the optical
system. However, in some applications that have precise wavelength
requirements, such as spectroscopic analyses or chromogenic assays
of complex samples, a filter 2 may be desirable.
[0039] In the illustrated embodiment, light emitted by LED source 1
is guided radially by a radial light guide 30 that includes a light
coupling total internal reflection (TIR) cone 35 for coupling the
emitted light into the radial light guide 30. As illustrated, light
coupling TIR cone 35 is centered within the radial light guide 30
and substantially above the LED source 1. In such a geometry, light
emitted by LED source 1 is substantially evenly transmitted from
the center of light guide 20 toward the perimeter of radial light
guide 30. Radial light guide 30 can be formed of, e.g., acrylic
cast into a mold that forms light coupling TIR cone 35. The radial
light guide 30 with a light coupling TIR cone 35 allows a 20 to 100
mW LED source 1 to provide as much illumination to the analyte
holding vessel 40 as a 20 W incandescent bulb.
[0040] A single well 45 configured to support an analyte holding
vessel 40 is illustrated beyond the perimeter of the radial light
guide 30. Naturally, it is both possible and desirable to use
plural wells 45 and analyte holding vessels 40 (not shown). The
distribution of such wells 45 relative to the radial light guide 30
will be discussed further in, e.g., FIGS. 3 and 11. The illustrated
well 45 is configured to support an analyte holding vessel 40 that
is a test tube, although other suitable vessels, such a optical
cuvettes and capillaries, may be used. It is only important that
analyte holding vessel 40 be sufficiently transparent over the
emission spectrum of LED source 1 to perform the desired assay.
[0041] The exemplary optical system of FIG. 2 also includes a pair
of light pipes 60 and 70 along a pair of paths that join the real
or virtual position of the LED source 1 and some point in or on an
analyte holding vessel 40 in the well 45. The pair of light pipes
60 and 70 neighbor the well 45. Light transmitted through the well
45 is incident upon the pair of light pipes 60 and 70 (provided no
analyte holding vessel 40 is present), and reflected in a direction
determined by the orientation of a total internal reflection (TIR)
surface 21. The pair of light pipes 60 and 70 thus allow an optical
transducer to be located away from a straight line path that join
the real or virtual position of the LED source 1 and some point in
or on the analyte holding vessel 40 in the well 45. This is
desirable in the interest of simplifying device design, limiting
the number of harness connections, decreasing the cost of the
device, and simplifying maintenance and repair. As illustrated, the
light receiving portion of light pipe 60 is located along a path
that joins the real or virtual position of the LED source 1 and a
point on the bottom curvature of an analyte holding vessel 40
positioned in the well 45. When an analyte holding vessel 40 is
present in well 45, light passing along this line through the
radial light guide 30 is significantly deflected out of this path
due to refraction by the analyte holding vessel 40, and a light
transducer 65 located at the output of light pipe 60 can easily
detect the insertion and/or removal of analyte holding vessel 40 by
monitoring the intensity of the received light. Absorption and/or
reflection of the light that passes along this path can also
decrease the intensity of the received light and detect the
presence of an analyte holding vessel 40 in well 45. Alternatively,
the light receiving portion of light pipe 60 can be located along a
path that joins the real or virtual position of the LED source 1
and a point on the side curvature of the analyte holding vessel 40
to obtain a similar sensitivity, as further illustrated in FIGS.
13A-C.
[0042] Light pipe 70, on the other hand, is preferably located
along a light path that joins the real or virtual position of the
LED source 1 and a point near the center of an inserted analyte
holding vessel 40, but away from the bottom. As such, a relatively
long pathlength through the analyte holding vessel 40 is examined
and refraction (due to, e.g., tubular analyte holding vessels 40)
is minimized.
[0043] In the illustrated embodiment of FIG. 1B, both light pipes
60 and 70 receive light from a same radial light guide 30. This is
not necessarily the case. For example, two different radial light
guides 20 can each transmit light to a single respective light pipe
60 and 70. Moreover, in the case of plural test wavelengths, even
three or more different radial light guides 20 can be used with
associated light pipes.
[0044] In the illustrated embodiment, both TIR surfaces 21 reflect
light downward, substantially at right angles relative to the
respective path of that light through the analyte holding vessel
40. This is preferred, since no tilting and/or stoppering of the
analyte holding vessel 40 is required and the light transducers 65
and 75 for multiple analyte holding vessels 40 can be positioned in
a single printed circuit board located below and substantially
parallel with the radial light guide 30. Naturally, in some
embodiments of the invention, the TIR surfaces 21 and pair of light
pipes 60 and 70 can be eliminated in whole or in part, although
this will often require the placement of the light transducers 65
and 75 for multiple analyte holding vessels 40 upon multiple
printed circuit boards. At the output of the pair of light pipes 60
and 70, a pair of light transducers 65 and 75 can be used to
determine the transmissivity of both optical paths. Suitable,
commercially available light transducers 65 and 75 include
photodiodes such as the Centrovision P/N BPW-34, Hamamatsu P/N
S4707-01, Hamamatsu P/N S3407-01, UDT Sensors P/N BPW34, UDT
Sensors P/N BPW34B, Infinion P/N BPW34, Infinion P/N BPW34 B, and
the Perkin Elmer P/N VTD34.
[0045] A further illustration of side views of various light paths
100, 101, and 102 through an exemplary optical system with and
without a sample holding vessel present is provided in FIGS. 2A,
2B, and 2C (albeit at higher magnification). In FIG. 2A, photons
generated at the LED source 1 are reflected by the light coupling
TIR cone 35 and carried along radial light guide 30 to a vessel
support 80 that may or may not support an analyte holding vessel 40
therein. If an analyte holding vessel 40 is not supported by the a
particular well 45 of the vessel support 80, then the light path
101 will conduct a relatively high intensity of light to light pipe
60, which in turn conducts the light to light transducer 65. On the
other hand, if a (filled) analyte holding vessel 40 is supported by
a particular well 45 of the vessel support 80, then light
originally on light path 101 is deflected along light path 102, and
a relatively low intensity of light is received at light pipe 60
and light transducer 65. Thus, by measuring an intensity of the
light received at light transducer 65, the presence of an analyte
holding vessel 40 in a well 45 of the vessel support 80 can be
made.
[0046] FIG. 2C illustrates a side view of various light paths
through an exemplary optical system with a sample holding vessel
present at an increased magnification. As illustrated, light that
has passed through the radial light guide 30 is directed downward
due to refraction caused by the base of an analyte holding vessel
40 in a well 45 of the vessel support 80. Refraction need not be
the physical origin of the decreased light intensity received at
light guide 60. For example, reflection and/or absorption can also
cause reduced light transmission to light guide 60.
[0047] As illustrated in FIGS. 2A, 2B, and 2C, since light path 100
is incident upon a position substantially at the middle of analyte
holding vessel 40, the direction of light path 100 remains
substantially unchanged by the presence of analyte holding vessel
40. Naturally, the intensity of light transmitted along light path
100 will change, and this intensity change will be used to assay
the contents of analyte holding vessel 40.
[0048] Also illustrated in FIG. 2A and 2B is a positioning sleeve
11 arranged about the LED source 1. The positioning sleeve 11
serves to accurately center LED source 1 directly under light
coupling TIR cone 35, ensuring substantially uniform radial
illumination by light guided through radial light guide 30.
[0049] FIGS. 3A and 3B illustrate, respectively, a top view and a
side view of an exemplary embodiment of the optical system that
includes a central light source with multiple wells 45 of the
vessel support 80 for holding multiple analyte holding vessels 40.
In the illustrated embodiment, the multiple wells 45 are arranged
radially about the light coupling TIR cone 35 of the radial light
guide 30. As such, the multiple wells 45 of the vessel support 80
receive substantially equal radiant fluxes from the LED source 1.
Moreover, if the vessel support 80 is radially symmetric, this
radial symmetry can be exploited to maintain all wells 45 of the
vessel support 80 at a substantially equal temperature. For
example, if the vessel support 80 includes a ring made of a
thermally conducting material (e.g., a metal such as aluminum or
copper such as heat conducting block 85 shown in e.g., FIG. 10),
then a heater ring (such as heater 90 shown in e.g., FIG. 10) can
be disposed just inside and/or outside of the vessel support 80 and
all wells 45 of the vessel support 80 will be maintained at a
substantially equal temperature. Thus, even if the absolute
incubation temperature is subject to errors due to, e.g., thermal
fluctuations and/or miscalibrated equipment, then accurate
differential measurements across samples within different wells 45
of the vessel support 80 will still be possible. Both the heating
of and disposition of wells 45 within the vessel support 80 will be
discussed in more detail in regard to FIG. 9.
[0050] FIGS. 4A and 4B illustrate, respectively, a top view and a
side view of a second exemplary embodiment of the radial light
guide 30, namely a curved wedge lightguide. As with the radial
light guide 30 of FIGS. 1A and 1B, the radial light guide 30 of
FIGS. 4A and 4B guides light emitted by LED source 1 (optionally
passing through a light filter 2) radially to multiple wells 45
within the vessel support 80. With curved wedge waveguides, plural
LED sources can be vertically staggered, and the light illuminating
the analyte holding vessels 40 in wells 45 appear to originate from
a single, central source 111. The radial light guide 30 of FIGS. 4A
and 4B is particularly useful for several different reasons. For
example, by reducing the total number of wells 45 that are
illuminated by a particular LED source 1, then the intensity per
well 45 is increased. This effect can be augmented by collecting
and/or focusing light upon the end of radial light guide 30 using,
e.g., lenses and spherical and/or parabolic reflectors (not shown).
The increased light intensity per well 45 is particularly useful
when, e.g., assaying samples with a low transmittance. Another
reason that the radial light guide 30 of FIGS. 4A and 4B is
particularly useful is that several such light guides and LED
sources 1 may be used in a single device for conducting assays.
This broadens the range of available assays that may be performed
upon the analyte holding vessels 40 in vessel support 80. For
example, some wells 45 of the vessel support 80 may be dedicated to
assaying for one chromophore, while other wells 45 may be dedicated
to assaying for another chromophore that has a different absorption
spectrum. Since different LED sources 1 can be used to sample
separate groups of wells 45, each chromophore can be probed at a
wavelength for which it has a near-maximum response (e.g.,
absorbance), and an increased sensitivity to each chromophore can
be achieved. Moreover, different filters can be inserted between
each of the LED sources 1 and the radial light guides 30.
[0051] FIGS. 5A and 5B illustrate, respectively, a top view and a
side view of an exemplary embodiment of the optical system that
includes the second exemplary embodiment of the radial light guide
30. Plural LED sources 1 are available in this optical system, and
light emitted by these LED sources 1 is substantially evenly
distributed along the perimeter of radial light guide 30 due to the
symmetric arrangement of plural versions of the second exemplary
embodiment of the radial light guide 30 about a central axis. As
described before, the plural LED sources 1 can have similar or
different emission spectra, as desired.
[0052] FIGS. 6A and 6B illustrate, respectively, a top view and a
side view of a third exemplary embodiment of the radial light guide
30, namely a lensmatic wedge lightguide. As with the radial light
guide 30 of FIGS. 1A and 1B, the radial light guide 30 of FIGS. 6A
and 6B guides light emitted by LED source 1 (optionally passing
through a light filter 2) radially to multiple wells 45 within the
vessel support 80. However, the lensmatic wedge lightguide has at
least one of the light coupling face 32 (where light is received
from the LED source 1) and a light decoupling face 31 (where light
is transmitted to the analyte holding vessels 40 in wells 45) with
a radius of curvature that is smaller than the radius of the one or
more concentric rows of wells 45 in the vessel support 80 for the
analyte holding vessels 40. The lensmatic wedge lightguide version
of the radial light guide 30 thus can be designed to create a
virtual image 111 of the LED source 1 directly at the center point
of the radius of one or more concentric rows of wells 45 in the
vessel support 80. Once again, substantially even radial
distribution of light emitted by plural LED sources 1 can be
assured, even though these sources do not occupy the same physical
space.
[0053] The third embodiment (lensmatic wedge) radial light guide 30
of FIGS. 6A and 6B is particularly useful for reasons similar to
those described in regard to the second embodiment (curved wedge)
of the radial light guide 30 of FIGS. 4A and 4B. For example, by
reducing the total number of analyte holding vessels 40 that are
illuminated by a particular LED source 1, then the intensity per
analyte holding vessel 40 is increased. This effect can be
augmented by collecting and/or focusing light upon the end of
radial light guide 30 using, e.g., lenses and spherical and/or
parabolic reflectors (not shown). The increased light intensity per
analyte holding vessel 40 is particularly useful when, e.g.,
assaying samples with a low transmittance. Another reason that the
third embodiment (lensmatic wedge) radial light guide 30 of FIGS.
6A and 6B is particularly useful is that several such lightguides
and LED sources 1 may be used in a single device for conducting
assays. This broadens the range of available assays that may be
performed upon the analyte holding vessels 40 in vessel support 80.
For example, some wells 45 of the vessel support 80 may be
dedicated to assaying for one chromophore, while other wells 45 may
be dedicated to assaying for another chromophore that has a
different absorption spectrum. Since different LED sources 1 can be
used to sample separate groups of wells 45, each chromophore can be
probed at a wavelength for which it has a maximum absorbance, and
an increased sensitivity to each chromophore can be achieved.
Moreover, different filters can be inserted between each of the LED
sources 1 and the radial light guides 30.
[0054] In contrast with the second embodiment (curved wedge) radial
light guide 30 of FIGS. 4A and 4B, multiple copies of the third
embodiment (lensmatic wedge) radial light guides 20 of FIGS. 6A and
6B can be maintained in a substantially single plane. As such, it
is easier to stack multiple layers of the third embodiment
(lensmatic wedge) radial light guides 20 so that each well 45 in
vessel support 80 can be assayed by a user-selected wavelength
independent of the location of well 45. A single well 45 may also
be assayed at multiple wavelengths using this approach by, e.g,
multiplexing the transmission wavelength through a single well 45
by shifting the phase of an on/off modulation for different LED
sources 1 stacked atop one another but illuminating a single well
45. The stacking of multiple layers of the third embodiment
(lensmatic wedge) radial light guides 20 can be accompanied by the
addition of further light pipe(s) and transducer(s) (sensitive to
the wavelength(s) of the further LED sources 1) so that complete
additional, independent, optical channels can be formed. Finally,
lensmatic wedge radial light guides 20 are relatively easy to
make.
[0055] FIGS. 7A and 7B illustrate, respectively, a top view and a
side view of an exemplary embodiment of an optical system that
includes the third exemplary embodiment of the radial light guide
30, namely the lensmatic wedge. Similarly to FIGS. 5A and 5B,
plural LED sources 1 are available in this optical system, and
light emitted by these LED sources 1 is substantially evenly
distributed along the perimeter of radial light guide 30 due to the
symmetric arrangement of plural versions of the third exemplary
embodiment of the radial light guide 30 about a central axis. As
described before, the plural LED sources 1 can have similar or
different emission spectra, as desired.
[0056] FIG. 8 illustrates a schematic of a top view of an exemplary
arrangement of a optical system that includes the third exemplary
embodiment of the radial light guide 30, namely the lensmatic
wedge. This is presented to emphasize that, in this case, all
radial light guides 20 can form a virtual image 111 of a respective
LED source 1 at a point central to all wells 45 of the vessel
support 80.
[0057] FIG. 9 illustrates an exemplary heat conducting block 85
from a vessel support 80 that contains two concentric circular rows
of wells 45. Also shown are a heater ring 90, a temperature
transducing thermistor 1000, a fixing dowel pin 6, 0-rings 41, and
dual light pipes 675. The heat conducting block 85 contains two
concentric circular rows of wells 45 configured to support an
inserted analyte holding vessel 40 (not shown). By using two
concentric circular rows of wells 45, the capacity of the
instrument (i.e., number of wells 45) can be increased. This allows
for the parallel assaying of multiple analyte holding vessels 40
without an unwieldy increase in the dimensions of the vessel
support 80. In one embodiment, there are 96 wells 45 within a
single vessel support 80, distributed in two concentric circular
rows.
[0058] In the illustrated embodiment, the wells 45 are relatively
deep and a significant portion of an inserted analyte holding
vessel 40 can be enclosed within each well 45. Thus, cross bores
(not shown) directed radially through the vessel support 80 are
necessary to allow the transmission of light through the vessel
support 80 to the wells 45 and light pipes 60 and 70.
[0059] The exemplary vessel support 80 also includes a heater ring
90 that surrounds the heat conducting block 85. By maintaining
radial symmetry about a central axis for both the heater ring 90
and the wells 45 in the heat conducting block 85, a relatively
equal temperature can be maintained at each well 45 in a single
row. As such, even if absolute temperature control is ineffective,
accurate differential measurements across analyte holding vessels
40 incubated in a same row can be made. In one embodiment, heater
ring 90 is formed from a low power, DC heater. The power supply for
such a heater ring 90 can be placed under microprocessor control
and, given that the supply is DC, a source of AC electrical noise
within the device for assays is eliminated.
[0060] The exemplary vessel support 80 also includes a temperature
transducing thermistor 1000 that is favorably disposed in contact
with or within the heat conducting block 85. The temperature
transducing thermistor 1000 can be used to generate a control
signal used for the closed loop control of the temperature of heat
conducting block 85. A suitable, commercially available thermistor
1000 is the P/N QT06002-128 REV A from Quality Thermistor, Inc. For
example, if the temperature transducing thermistor 1000 indicates
that the temperature of the heat conducting block 85 has dropped
below a predetermined (and possibly operator-set) temperature, then
increased power can be presented to heater ring 90, and the
temperature of the heat conducting block 85 increased. In some
embodiments of the device, assay incubation temperature is
maintained at 37.degree..+-.0.1.degree. C. using a calibrated
thermistor with a .+-.0.1.degree. C. accuracy. The look-up table
for the temperature transducing thermistor 1000 is stored in a
memory, and the temperature transducing thermistor 1000 is read
every 3 seconds via a 12 bit A/D converter. This digital signal
corresponds to the control signal for the feedback loop, and a
microcontroller increases power applied to the heater when the
apparent temperature drops below 36.9.degree. C. and decreases
applied power when the apparent temperature exceeds 37.1.degree.
C.
[0061] The exemplary vessel support 80 can also include an O-ring
41 that can be sandwiched in each well 45. An O-ring 41 so disposed
along the interior of well 45 provides enough resistance to falling
such that an analyte holding vessels 40 that is placed into a well
45 will not drop and splash the analyte. Moreover, such O-rings 41
are inexpensive and replaceable.
[0062] The exemplary vessel support 80 can also include an dual
light pipe 675 that includes each of light pipes 60 and 70 inserted
into the base of heat conducting block 85. Dual light pipe 675 can
be used to maintain a constant spatial relationship between each of
light pipes 60 and 70.
[0063] Finally, the exemplary vessel support 80 can also include a
fixing dowel pin 6 that can be inserted into heat conducting block
85 used to fix the relative angular position of the heat conducting
block 85 relative to any support or cover therefor.
[0064] FIG. 10 illustrates the assembly of an assay device
according to the present invention. The device for assays is
enclosed within a base 200 and a cover 800 that protect the optical
and electronic components from, e.g., dust, water splashes, and
other environmental hazards. In the illustrated embodiment, all
light transducers 65 and 75 are arranged on a single printed
circuit board assembly 300 to receive light output from a
respective light pipe 60 or 70. Some or all electronic signal
processing elements can be located on a single printed circuit
board assembly 300, such as, e.g., timing elements, A/D converters,
channel multiplexers, electrical filters, switches, and/or buffers.
Either a raw or a processed (e.g., sampled and filtered) output
from the individual light transducers 65 and 75 can be relayed to
an external control/record processor by way of a multi-pin bulkhead
connector (not shown) affixed to, e.g., the side wall of base 200.
Naturally, plural printed circuit board assemblies 300 can be used
in some embodiments of the invention.
[0065] Depending upon the thickness of heat conducting block 85,
one or more LED source(s) 1 and radial waveguide(s) 30 can be
disposed substantially concentrically within heater 90 and heat
conducting block 85. If heat conducting block 85 is relatively
thick, then one or more of the light paths 100 and 101 can pass
through heat conducting block 85. This can be accomplished by
boring radial holes to transmit the light emitted from radial
waveguide(s) 30 through an analyte holding vessel 40 in a well 45
to a respective light pipe 60 or 70 which is affixed within heat
conducting block 85. The respective light pipe 60 or 70, which can
be fixed within a hole bored into the heat conducting block 85 in
an axial direction, can then transmit the light to the respective
light transducer 65 or 75 on printed circuit board assembly 300. As
mentioned before, if further optical channels capable of making
measurements upon a single analyte holding vessel 40 in a well 45
are added, then additional light pipes and light transducers can be
added, as needed.
[0066] The illustrated device for assay has two separate radial
waveguides 30 according to the first described embodiment, one
which transmits light along light path 100 for assaying and one
which transmits light along light path 101 for detecting an analyte
holding vessel 40. Naturally, other numbers and types of radial
waveguides 30 are available under the current invention. Moreover,
one or more radial waveguide(s) 30 can be disposed such that they
transmit light above heat conducting block 85 to a respective light
pipe 60 or 70, which may or may not be affixed within the heat
conducting block 85. In such a case, it may be desirable to
optically isolate the individual analyte holding vessels 40 by
interposing an opaque sheet between neighboring analyte holding
vessels 40.
[0067] The two separate radial waveguides 30 are themselves
optically isolated from one another through an optical separator
400. Such an optical separator can be formed, e.g., from a thin
metallic or polymeric piece that is substantially opaque in the
wavelengths used by the respective one or more LED source(s) 1.
[0068] In the illustrated embodiment, an insulating shell 500 is
disposed and affixed atop the heat conducting block 85 and/or
heater 90 to form vessel support 80. The insulating shell 500 can
serves multiple purposes. Firstly, by thermally isolating the heat
conducting block 85 and/or heater 90, the power requirements of the
heater 90 can be reduced, and more uniform heating across the heat
conducting block 85 can be obtained. Furthermore, even if
insulating shell 500 were in physical contact with base 200, then
conductive thermal transport to base 200 can be minimized.
Moreover, since the insulating shell 500 reduces the power
requirements of heater 90 for maintaining a substantially constant
incubation temperature, a DC heater 90 can be used, which is easily
amenable to microprocessor-based control and eliminates background
electrical noise by removing a high power AC component from the
assay device. This is particularly beneficial when a printed
circuit board assembly 300 contains some and/or all of the
processing equipment, since the base 200 and a cover 800 can form,
in some embodiments, a Faraday cage with only DC power feed lines
for the internal electronic circuitry.
[0069] Another advantage of the insulating shell 500 is that it
allows for the minimization of the thickness of the conducting
block 85 within the vessel support 80, and hence reduces the total
weight of the instrument. For example, the insulating shell 500 can
have a top face that is displaced from the conducting block 85 and
holes (not shown) that support the analyte holding vessels 40 can
be drilled through this top face. Thus, an analyte holding vessel
40 that is inserted into a well 45 is supported both at the
conducting block 85 and at the insulating shell 500. The use of an
insulating shell thus allows for the minimization of the thickness
of conducting block 85 in the vessel support 80 while maintaining
support for an analyte holding vessels 40 with a minimal increase
in weight, since insulating shell 500 can be made from, e.g., a
polymer. An example material for the insulating shell 500 is DELRIN
(acetal).
[0070] Yet another advantage of the insulating shell 500 is that it
can serve to fix the position of other components, including the
O-rings 41 and the radial light guide(s) 20, relative to the
conducting block 85 and wells 45.
[0071] In the embodiment illustrated in FIG. 10, an indicator
assembly layer including a cover 700 and an LED indicator assembly
600 is included between the insulating shell 500 and the cover 800.
Both the cover 700 and LED indicator assembly 600 can be used to
provide a human operator with information regarding the wells 45.
For example, an alphanumeric denominator for each well 45 can be
included upon the cover 700 and the LED indicator assembly 600 can
be used, e.g., to indicate to an operator that the assay device
considers that an analyte holding vessel 40 has been inserted into
a particular well 45. Thus, operator error due to incomplete and/or
incorrect insertion of an analyte holding vessel 40 can be
avoided.
[0072] FIG. 11 illustrates a wireframe view of an exemplary 96 well
assembled assay device. The 96 wells in the illustrated exemplary
device are arranged in two concentric circular rows about a center
point which contains a real or virtual LED source 1. The locations
of the wells 45 along the two rows are furthermore offset with
regard to one another, so that a clear optical path to the outer
wells from the real or virtual LED source 1 exists. Finally, there
need not be any moving parts in the assay device, and moreover the
entire device can be microprocessor controlled and DC powered.
[0073] FIG. 12 illustrates an exemplary electronics block diagram
of an assay device. As mentioned before, a single control/record
processor 610 can be used to control operation of the elements of
the assay device, as well as to record the results of the assays.
For example, the resistance of thermistor 1000 can be measured by,
e.g., placing thermistor 1000 in a bridge and digitizing a
differential voltage across the bridge using an A/D convertor 660.
The digitized differential voltage can be relayed to the
control/record processor 610 which might have access to, e.g., a
look-up table that associates certain differential voltages with
certain temperatures. An exemplary commercially available
control/record processor 610 is the Motorola P/N MC68HC711E9FN3.
The control/record processor 610 can then compare the digitized
differential voltage with a reference value, and increase and/or
decrease the power output to heater 90 as needed. This will be
discussed in more detail in regard to FIG. 14.
[0074] Another method of determining a temperature is through the
use of a manufacturer-calibrated thermistor 1000. An R-T look-up
table is provided by the manufacturer for such devices. In this
case, the A/D converter 660 measures an absolute potential drop and
hence resistance across the thermistor 1000.
[0075] Another function of the control/record processor 610 is
implemented using a digital connection to an LED source 1 intensity
controller 650. This intensity controller 650 can receive digital
intensity control signals from the control/record processor 610 and
use them to increase and/or decrease the bias voltage applied to
one or more of the LED sources 1. This will be done, e.g., when an
analyte holding vessel 40 is newly inserted into a particular well
45, or when an the light received by a light transducer 75 is too
low in intensity for an accurate measurement to be made by a light
transducer 75. The intensity controller 650 can also be used to
modulate the bias voltage applied to the LED sources 1 as
needed.
[0076] In order for the applied bias voltage to effect a light
emission from the LED sources 1, a suitable voltage across the LED
sources 1 must exist (i.e., the LED sources 1 must be forward
biased). This too can be determined by the control/record processor
610, which uses a light source multiplexer 655 to selectively
complete a return electrical current path through one or more
particular LED sources 1. The light source multiplexer 655 can
selectively forward bias an LED source 1 in response to, e.g., the
insertion of an analyte holding vessel 40 into a particular well 45
serviced by an LED source 1, the selection of a certain assay
wavelength by an operator corresponding to the emission of LED
source 1, or simply to effect an on/off modulation as described in
more detail in FIG. 15.
[0077] A separate vessel detect light source 1 is illustrated in
FIG. 12 for the sake of illustrating separate control of the vessel
detect optical path when a dedicated radial light guide 30 is used
to form light path 101. This vessel detect light source 1 can also
be formed by an LED and controlled using a light source multiplexer
655 and intensity controller 650 as described above.
[0078] Another way that the control/record processor 610 can
respond to light transducer 75 receiving an insufficient light
intensity is by changing an amplification gain for an amplifier
associated with one or more light transducer(s) 75. This can be
done by transmitting a well select signal to well selection unit
620 along with a digital gain adjust signal to the gain adjuster
635, which in turn can increase the gain of signal amplifier 645
for the selected well 45. The well selection unit 620 can be formed
of another multiplexer that selects the output of a particular well
45 for input to the signal amplifier 645. Naturally, plural well
selection units 620, signal amplifiers 645, and gain adjusters 635
can be used as well to produce a similar action.
[0079] A similar process can be used to adjust a light intensity
cut-off level for determining when an analyte holding vessel 40 is
present in one or more wells 45. Digital level adjuster 630 can be
used to set an appropriate voltage for the vessel detect comparator
640 that is midway between the output voltage of light transducer
65 when an analyte holding vessel 40 is present and the output
voltage of light transducer 65 when an analyte holding vessel 40 is
absent from a well 45. A voltage set signal can be transmitted from
control/record processor 610 to digital level adjuster 630 at the
same time that the appropriate well is identified to well selection
unit 620. Once again, plural well selection units 620, level
adjusters 630, and vessel detect comparators 640 can be used as
well to produce a similar action.
[0080] The control/record processor 610 can also be used to
generate a ready signal, and error signal, and/or other indicator
signals for output to indicator 11. The indicator 11 thus serves to
provide operation information to an operator.
[0081] The control/record processor 610 can also be used to handle
communications with another control/record processor 610, an output
and/or input device, and/or with one or more computer-readable
memory devices by way of a communications port 670. These functions
will be discussed further in regard to FIG. 16.
[0082] FIGS. 13A-C illustrate a top view in the absence of an
analyte holding vessel 40, a top view in the presence of an analyte
holding vessel 40, and a side view in the presence of an analyte
holding vessel 40 that uses an exemplary side wall tube detection
scheme with a single radial light guide 30. In the illustrated
example, both the light paths 100 and 101 (as well as 102) pass
through a single radial light guide 30 with the light path 101
simply being displaced by some angle from light path 100 within the
single radial light guide 30. As illustrated, the side wall of the
analyte holding vessel 40 deflects the path of light that travels
down light path 101 without the analyte holding vessel 40 present
in the well 45 to the light path 102 when the analyte holding
vessel 40 is present in the well 45. This configuration is
particularly advantageous when a flat-bottomed analyte holding
vessel 40 as illustrated in FIG. 13C is used.
[0083] Furthermore, the side wall detection scheme illustrated in
FIGS. 13A-C provides two further advantages. When the analyte
holding vessel 40 is a test tube, the side wall curvature is often
manufactured to tighter tolerances than the radius of the bottom of
these vessels. As such, more reliable detection of these vessels
can be obtained. Furthermore, regardless of the type of analyte
holding vessel 40, sidewall detection allows the minimization of
the length of light path 100. Since light pipe 70 can be brought
closer to the well 45, the length of the light path 100 can be
decreased, and the intensity of the light received by light pipe 70
increased.
[0084] FIG. 14 illustrates an exemplary process loop for monitoring
and controlling the incubation temperature according to the present
invention. In one embodiment, this process loop is performed at all
times during operation of the assay device. In other words, an
analyte holding vessel 40 need not be inserted into a well 45. In
step 1210, the temperature is read using temperature transducing
thermistor 1000 which can be precalibrated with corresponding
temperature and resistances stored in a look-up table in
computer-readable memory. Alternatively, temperature transducing
thermistor 1000 can be linearized over a temperature range near a
common incubation temperature such as 37.0.degree. C. In either
case, once a temperature (and/or corresponding resistance) has been
determined, it is recorded in step 1220. This can be done by
writing to a computer readable memory, such as the illustrated
Pyros data block 1000. Recordation of the temperature in step 1220
need not always be performed. For example, in the case of a long
assay time, only one in a certain number of measured temperatures
need be recorded. Alternatively, if no analyte holding vessels 40
are located in a well 45, then temperature need not be
recorded.
[0085] In step 1230, a determination is made as to whether the
temperature read in step 1210 is within a certain range. In the
illustrated process loop, if the read temperature is less than
37.1.degree. C. and greater than 36.9.degree. C., then the process
flow returns to step 1210, perhaps after a suitable delay. However,
if the read temperature is less than 36.9.degree. C., then the
process flow proceeds to step 1280, where the heater control
indicates that the power to the heater 90 should be increased. In
step 1285, another determination is made as to whether the
temperature read in step 1210 falls within a certain range. The
determination in step 1285 is made to determine whether a critical
temperature situation due to underheating exists. For example, if
the read temperature is less than 36.5.degree. C., then a critical
situation is indicated to the operator by setting a front panel LED
indicator to red in step 1295. The assay device also sets an
internal status indicator to a value, e.g., 0, that indicates the
presence of a critical temperature situation due to underheating.
After the critical temperature situation is indicated to both the
user and/or other portions of the device, both the temperature and
status is recorded in step 1270 by writing to, e.g., the
illustrated Pyros data block 1000. After recordation of the
temperature and status, the process flow loops back to step
1210.
[0086] In step 1235, if it is determined that a critical
temperature situation does not exist, then the process flow
proceeds to step 1270 without indicating a critical temperature
situation to the user and/or other portions of the device. Once
again, both the temperature and status can be recorded in step 1270
as needed by writing to, e.g., the illustrated Pyros data block
1000. After recordation of the temperature and status, the process
flow loops back to step 1210.
[0087] In step 1230, if the read temperature is greater than
37.1.degree. C., then the process flow proceeds to step 1240, where
the heater control indicates that the power to the heater 90 should
be decreased and/or cut off. In step 1250, another determination is
made as to whether the temperature read in step 1210 falls within a
certain range. The determination in step 1250 is made to determine
whether a critical temperature situation due to overheating exists.
For example, if the read temperature is greater than 37.5.degree.
C., then a critical situation is indicated to the operator by
setting a front panel LED indicator to red in step 1260. The assay
device also sets an internal status indicator to a value, e.g., 2,
that indicates the presence of a critical temperature situation due
to overheating. After the critical temperature situation is
indicated to both the user and/or other portions of the device,
both the temperature and status can be recorded in step 1270 by
writing to, e.g., the illustrated Pyros data block 1000. After
recordation of the temperature and status, the process flow loops
back to step 1210.
[0088] In step 1250, if it is determined that a critical
temperature situation does not exist, then the process flow
proceeds to step 1270 without indicating a critical temperature
situation to the user and/or other portions of the device. Once
again, both the temperature and status can be recorded in step 1270
by writing to, e.g., the illustrated Pyros data block 1000. After
recordation of the temperature and status, the process flow loops
back to step 1210.
[0089] FIG. 15 illustrates a process flow for an exemplary on/off
modulation of the light output by LED source 1 for background
correction. In the on/off modulation, a background light level is
first determined for a particular light transducer, and then a
transmitted light measurement is performed. The background level
can thus be subtracted out, and more accurate measurements made. In
step 1300, a LED source 1 that provides the majority of the
illumination for a particular well 45 is shut off. In a preferred
embodiment, a particular well 45 already has an analyte holding
vessel 40 inserted therein. The particular well 45 can be
operator-identified, or the instrument can constantly cycle around
all available (e.g., filled) wells 45 and the particular well 45
can just happen to be a next well in line. In either case, the
address of the particular well 45 is selected in step 1310 so that
a background output of the light transducer 75 (and even a light
transducer 65, as needed) can be digitized and/or otherwise
processed for storage. Thereafter, in step 1320, the background
output of the light transducer 75 is read and/or digitized. After
information related to the background output of the light
transducer 75 has been stored, the process flow proceeds to step
1330 where the LED source 1 that provides the majority of the
illumination for a particular well 45 is turned on. The light
transmitted through the analyte holding vessel 40 when the LED
source 1 is turned on is termed the "sample value." In step 1340,
one or more "sample values" are read over a period of time so that
the contents of the analyte holding vessel 40 can be, e.g.,
turbidometrically and chromogenically assayed. Before the read
"sample values" are, e.g., displayed and/or stored in a
computer-readable memory, the read background output of the light
transducer 75 is subtracted from the "sample values." Naturally,
both the unchanged "sample values" and the read background output
of the light transducer 75 can be stored and the subtraction
operation performed, e.g., only upon the request of an
operator.
[0090] Modulation of the intensity of emitted light from LED source
1 need not be implemented as described (single step on/off) in
regard to FIG. 15. For example, a sinusoidal modulation of the
output intensity of LED source 1 with phase locking can be used to
discriminate between the light originating from a particular LED
source 1 and background (including other LED sources 1, provided
the other sources aren't similarly modulated). As another example,
the on/off modulation can occur continuously during assaying, so
that a continuous measurement of background is made.
[0091] As another example of a useful modulation, the light emitted
from LED source 1 can be controlled to follow a predetermined
intensity as a function of time. This intensity as a function of
time can be selected, e.g., to mimic the intensity as a function of
time that would be observed if a particular assay were being
performed. Thus, if all analyte holding vessels 40 are removed from
the wells 45, then the light from a single LED source 1 can be
substantially uniformly transmitted to plural (or even all) light
transducers 75 simultaneously. Thus, the measured intensities for
each of the separate optical channels can be compared and each
optical channel can be calibrated.
[0092] FIG. 16 illustrates a computer system 801 that can form an
external control/record processor in an embodiment of the present
invention. For example, computer system 801 can communicate with
control/record processor 610 of FIG. 12 by way of communications
port 670.
[0093] Computer system 801 includes a bus 802 or other
communication mechanism for communicating information, and a
processor 803 coupled with bus 802 for processing the information.
Computer system 801 also includes a main memory 804, such as a
random access memory (RAM) or other dynamic storage device (e.g.,
dynamic RAM (DRAM), static RAM (SRAM), synchronous DRAM (SDRAM),
flash RAM), coupled to bus 802 for storing information and
instructions to be executed by processor 803. In addition, main
memory 804 may be used for storing temporary variables or other
intermediate information during execution of instructions to be
executed by processor 803. Computer system 801 further includes a
read only memory (ROM) 805 or other static storage device (e.g.,
programmable ROM (PROM), erasable PROM (EPROM), and electrically
erasable PROM (EEPROM)) coupled to bus 802 for storing static
information and instructions for processor 803. A storage device
807 and/or 808, such as a magnetic disk or optical disk, is
provided and coupled to bus 802 by way of a disk controller 806 for
storing information and instructions. Storage device 807 and/or 808
can contain the tables that record operating and/or measurement
information, such as the Pyros data block 1000 of FIG. 14.
[0094] The computer system 801 may also include special purpose
logic devices (e.g., application specific integrated circuits
(ASICs)) or configurable logic devices (e.g., generic array of
logic (GAL) or reprogrammable field programmable gate arrays
(FPGAs)). Other removable media devices (e.g., a compact disc,
flash memory cards, a tape, and a removable magneto-optical media)
or further fixed, high density media drives, may be added to the
computer system 801 using an appropriate device bus (e.g., a small
computer system interface (SCSI) bus, an enhanced integrated device
electronics (IDE) bus, or an ultra-direct memory access (DMA) bus).
Such removable media devices and fixed, high density media drives
can also contain the tables that record operating and/or
measurement information, such as the Pyros data block 1000 of FIG.
14. The computer system 801 may additionally include a compact disc
reader, a compact disc reader-writer unit, or a compact disc juke
box, each of which may be connected to the same device bus or
another device bus.
[0095] Computer system 801 may be coupled via bus 802 to a display
810, such as a cathode ray tube (CRT), for displaying information
to a computer user. Display 810 can perform the functions of an
indicator 11 as seen in FIG. 12, especially when the assay device
is operated remotely from the computer system 801. The display 810
may be controlled by a display or graphics card. The computer
system includes input devices, such as a keyboard 811 and a
pointing device 812 (e.g., a cursor control), for communicating
information and command selections to processor 803. The pointing
device 812 (e.g., cursor control), for example, is a mouse, a
trackball, or cursor direction keys for communicating direction
information and command selections to processor 803 and for
controlling cursor movement on the display 810.
[0096] The computer system 801 can perform a portion or all of the
processing steps of the invention in response to processor 803
executing one or more sequences of one or more instructions
contained in a memory, such as the main hard disk memory 807. Such
instructions may be read into the main hard disk memory 807 from
another computer readable medium, such as storage device 808. One
or more processors in a multi-processing arrangement may also be
employed to execute the sequences of instructions contained in main
hard disk memory 807. In alternative embodiments, hard-wired
circuitry may be used in place of or in combination with software
instructions. Thus, embodiments are not limited to any specific
combination of hardware circuitry and software.
[0097] As stated above, the system 801 includes at least one
computer readable medium or memory programmed according to the
teachings of the invention and for storing data structures, tables,
records, or other data described herein. Examples of computer
readable media are compact discs, hard disks, floppy disks, tape,
magneto-optical disks, PROMs (EPROM, EEPROM, Flash EPROM), DRAM,
SRAM, SDRAM, etc. Stored on any one or on a combination of computer
readable media, the present invention includes software for
controlling the computer system 801, for driving a device or
devices for implementing the invention, and for enabling the
computer system 801 to interact with a human user. Such software
may include, but is not limited to, device drivers, operating
systems, development tools, and applications software. Such
computer readable media further includes the computer program
product of the present invention for performing all or a portion
(if processing is distributed) of the processing performed in
implementing the invention.
[0098] The computer code devices of the present invention may be
any interpreted or executable code mechanism, including but not
limited to scripts, interpreters, dynamic link libraries, Java
classes, and complete executable programs. Moreover, parts of the
processing of the present invention may be distributed for better
performance, reliability, and/or cost.
[0099] The term "computer readable medium" as used herein refers to
any medium or media that participate in recording data and/or
providing instructions to processor 803 for execution. A computer
readable medium may take many forms, including but not limited to,
non-volatile media, volatile media, and transmission media.
Non-volatile media includes, for example, optical, magnetic disks,
and magneto-optical disks, such as storage device 807 and/or 808.
Transmission media includes coaxial cables, copper wire and fiber
optics, including the wires that comprise bus 802. Transmission
media also may also take the form of acoustic or light waves, such
as those generated during radio wave and infrared data
communications.
[0100] Common forms of computer readable media include, for
example, hard disks, floppy disks, tape, magneto-optical disks,
PROMs (EPROM, EEPROM, Flash EPROM), DRAM, SRAM, SDRAM, or any other
magnetic medium, compact disks (e.g., CD-ROM), or any other optical
medium, punch cards, paper tape, or other physical medium with
patterns of holes, a carrier wave (described below), or any other
medium from which a computer can read.
[0101] Various forms of computer readable media may be involved in
carrying out one or more sequences of one or more instructions to
processor 803 for execution. For example, the instructions may
initially be carried on a magnetic disk of a remote computer. The
remote computer can load the instructions for implementing all or a
portion of the present invention remotely into a dynamic memory and
send the instructions over a telephone line using a modem. A modem
local to computer system 801 may receive the data on the telephone
line and use an infrared transmitter to convert the data to an
infrared signal. An infrared detector coupled to bus 802 can
receive the data carried in the infrared signal and place the data
on bus 802. Bus 802 carries the data to main hard disk memory 807,
from which processor 803 retrieves and executes the instructions.
The instructions received by main hard disk memory 807 may
optionally be stored on a removable media storage device 808 either
before or after execution by processor 803.
[0102] Computer system 801 also includes a communication interface
813 coupled to bus 802. Communication interface 813 can be
connected to communication port 670 of an internal control/record
processor 610, or internal control/record processor 610 can be
eliminated in whole or in part and the communication interface 813
can conduct direct communications with, e.g., level adjuster 630
and gain adjuster 635. In any such implementation, communication
interface 813 sends and receives electrical, electromagnetic, or
optical signals that carry data representing various types of
information.
[0103] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
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