U.S. patent number 3,856,470 [Application Number 05/322,323] was granted by the patent office on 1974-12-24 for rotor apparatus.
This patent grant is currently assigned to Baxter Laboratories, Inc.. Invention is credited to Herbert M. Cullis, Willard E. Fordham, Charles I. Soodak.
United States Patent |
3,856,470 |
Cullis , et al. |
December 24, 1974 |
ROTOR APPARATUS
Abstract
A rotor assembly for an apparatus adapted for monitoring a
chemical reaction and identifying the presence of certain
substances in each of a multiplicity of discreet samples. The
assembly includes a transfer disc for storing individually the
various constituents of one or more independent reactions and a
cuvette rotor disposed concentrically thereto. The cuvette rotor
provides in the path of light to a photoresponsive device a
multiplicity of chambers for receipt of the constituents of each
reaction. Means are provided in the cuvette rotor to heat the
constituents to optimum temperature and to maintain the
constituents at that temperature during the reaction time.
Inventors: |
Cullis; Herbert M. (Silver
Spring, MD), Fordham; Willard E. (Laurel, MD), Soodak;
Charles I. (Silver Spring, MD) |
Assignee: |
Baxter Laboratories, Inc.
(Morton Grove, IL)
|
Family
ID: |
23254376 |
Appl.
No.: |
05/322,323 |
Filed: |
January 10, 1973 |
Current U.S.
Class: |
422/64; 356/427;
422/82.09; 494/10; 494/33; 494/81; 422/72; 422/109; 494/13;
494/41 |
Current CPC
Class: |
G01N
21/07 (20130101) |
Current International
Class: |
G01N
21/07 (20060101); G01N 21/03 (20060101); F25b
021/02 (); B04b 015/02 (); G01n 001/10 (); G01n
021/00 () |
Field of
Search: |
;23/23R,253R,259,292
;233/11,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Serwin; R. E.
Attorney, Agent or Firm: Smith, Jr.; Samuel B. Kinney;
Richard G.
Claims
Having described the invention, I claim:
1. In a photometric solution analyzer comprising a power-driven
rotor assembly which defines a multiplicity of sample analysis
chambers for accepting liquid samples to be analyzed, said rotor
assembly having transparent walls adjacent said sample analysis
chambers for permitting the passage of light therethrough and a
multiplicity of chambers adapted to retain liquid samples and
reactants when said rotor assembly is at rest, and to release said
liquid samples and reactants to said sample analysis chambers when
said rotor is rotated; and stationary photometric means for
detecting changes in the analysis chambers by passing a beam of
light through the transparent walls of said rotor assembly, the
improvement comprising:
electric powered temperature adjusting means mounted on, and
rotatable with, said photometric assembly;
electric output producing temperature sensing means mounted on, and
rotatable with, said photometric rotor assembly; and
means coupled to said temperature adjusting means and said
temperature sensing means for controlling the temperature adjusting
means to precisely maintain the temperature of said photometric
rotor assembly at a selected value.
2. The invention of claim 1 wherein:
said temperature adjusting means is a resistance electrical heater,
said rotor assembly is, in large part, formed of a heat-conductive
material, and said electrical heater is disposed in a flat layer
adjacent to the said rotor assembly.
3. The invention of claim 2 wherein:
said temperature sensing means is a thermistor and is mounted away
from said flat temperature adjusting means, in proximity to a wall
of an optical cell of the rotor apparatus, and within the
conductive material of the rotor assembly.
Description
The present invention generally relates to an apparatus capable of
sequentially monitoring several chemical reactions. Through
monitoring the presence of certain substances in each of a
multiplicity of discreet samples may be determined. More
particularly, the present invention relates to a rotor assembly of
the apparatus. The rotor assembly includes a transfer disc in which
constituents are disposed individually, one from the other, and a
cuvette rotor for receipt of the constituents in a multiplicity of
optical viewing chambers. The cuvette rotor includes means adapted
to heat quickly and accurately the reacting constituents within the
chamber and thereafter to maintain the reacting constituents at the
temperature to which they were heated.
Typical of apparatus of the type contemplated herein is the
computer interfaced analyzer developed under the aegis of the
National Institute of General Medical Sciences and the United
States Atomic Energy Commission. The computer interfaced analyzer
has come to be known as the GeMSAEC system. The system is automated
to monitor a reaction from time zero to completion. A readout
indicative of all or a part of the reaction may be provided.
For further discussion concerning the interfaced electronics
package and, for example, a specific discussion of the make-up of
certain embodiments of the transfer disc to store separately the
reacting materials until mixed upon operation, reference may be had
to U.S. Pat. Nos. 3,536,106, 3,547,547, 3,555,284, 3,582,218 and
3,586,484, issuing to Norman G. Anderson and U.S. Pat. No.
3,514,613, issuing to Douglas N. Mashburn, all of which are
assigned to the United States Atomic Energy Commission. For the
sake of present discussion the transfer disc may provide at least
two wells which are radially spaced from the axis of rotation of
the disc. Separate constituents are disposed in each well. A
passage, also radially spaced from the axis of rotation,
communicates the separate constituents to a chamber of a cuvette
rotor of the present invention.
The aforementioned GeMSAEC system while constituting a significant
forward step in the biochemical and clinical analyses fields
suffers from one significant disadvantage. In this connection and
as best as can be determined in the prior art as a whole there has
been no attempt to provide means in an automated system to heat and
to maintain the reactants at a predetermined temperature.
One important application of the apparatus is the performance of
chemical analysis, especially of clinically significant blood
enzymes. The apparatus monitors optical changes which occur not
only upon mixing of serum with a particular reagent but also during
the reaction which follows. The optical changes are
stoichiometrically related to the quantity or extent of the
chemical reaction. Since the degree of completion of all chemical
reactions is temperature dependent, the measurement of chemical
reaction processes must reflect a consideration of temperature.
More particularly, however, it is important that the reacting
constituents be brought quickly to the desired temperature. In this
connection the recordation of data must begin when the reactants
are at the appropriate temperature. The measurement of blood
enzymes is made by determining the rate at which the enzyme reacts,
which reaction will commence as soon as the reactants are combined.
Generally, the maximum time allowable for temperature adjustment is
about 60 seconds. Preferably, however, the reactants should be at
the adjusted temperature, which may be within a range of, for
example, 0.degree. to about 50.degree.C., within about 30 seconds.
The adjusted temperature of the reactants and the specific absolute
temperature that chemical reactions are conducted is dictated
according to international convention for the procedures
contemplated. For example, most test procedures for any given
chemical analysis contemplate a specific absolute temperature of
either 25.degree., 30.degree. or 37.degree.C., corrected to
30.degree.C. if conducted at a specific absolute temperature of
other than 30.degree.C.
The present invention provides in apparatus of the foregoing type
means for heating reacting constituents. In one important aspect of
the present invention the cuvette rotor incorporates a heating
component in substantial intimate contact with the surface of each
chamber forming a cuvette cell into which the reactants are
received.
As will be described in detail hereinafter the cuvette rotor may be
formed of material having good thermal conductivity capability
thereby to rapidly conduct heat from the heating structure to the
liquid reactants in contact with the walls throughout the chamber
region. The material, as will also be described, must have other
characteristics in order to prevent occurrence of certain
analytical problems and/or deleterious effects. Thus, the cuvette
rotor should be formed of a material which is inert so as not to
affect the reaction of the liquids and the data being recorded. The
material must also present a surface to the reactants which will
prevent physical bonding thereto of proteinaceous materials
expected to be present in samples of blood. In this connection, it
is expected that the cuvette rotor will be subject to repeated
use.
As a further aspect of the present invention, the heating component
within the cuvette rotor is subject to regulation. The heating
component provides within critical tolerance accurate heating
capability within a range of temperatures as required for any test
procedure. In accordance with this aspect of the invention the
heating component is continually monitored so as to maintain the
temperature of the reactants at the regulated level of heat
energy.
In a further aspect of the present invention, there is provided
means in the cuvette rotor to exhaust the reactants from the
chamber after the desired data has been derived. To this end the
cuvette rotor provides siphon structure communicating with each
chamber. During data retrieval the siphon is inoperable. However
the addition of pressure to the chamber causes the reactants to
exit the chamber. The exhausted reactants are collected as waste.
Additional pressure will likewise be required during the washing of
the cuvette chambers after each test and preparatory to a
subsequent test.
An additional aspect of the present invention is in the
incorporation of means in conjunction with the cuvette rotor to
prevent a buildup of a static charge of electricity on the rotating
optical surfaces. The build-up of a charge may be prevented by the
use of a grounded metal foil gasket in contact with the optical
surfaces.
The foregoing description serves to outline in broad terms certain
of the more important features of the invention in order for the
description in detail which follows to be understood, and in order
for the present contribution to the art to be better appreciated.
There are, of course, additional features of the present invention
that will be particularly described below which also will form the
subject of the claims appended hereto. Those skilled in the art to
which the present invention pertains will appreciate that the
conception upon which this disclosure is based may readily be used
as a basis for the design of other structures for carrying out the
several purposes of the invention. It is important, therefore, that
the claims be regarded as including such equivalent construction as
do not depart from the spirit and scope of the invention.
The accompanying drawings, forming a part of the present
application, illustrate a preferred embodiment of the present
invention. By the drawings
FIG. 1 illustrates in elevation and partly in section an apparatus
for use in measuring chemical reactions;
FIG. 2 is a bottom plan view of a portion of the rotor of the
apparatus of FIG. 1, and particularly the portion of the rotor
capable of being heated under controlled conditions;
FIG. 3 is an exploded view of the rotor portion of FIG. 2;
FIG. 4 is a top plan view of the structure of FIG. 2;
FIG. 5 is an enlarged view of the portion of FIG. 4 which is
denoted by the circle in phantom;
FIG. 6 is a cross-sectional view as seen along the line 6--6 in
FIG. 5; and
FIG. 7 is a schematic view of the heating and sensing circuit as
employed.
The structure as seen in FIG. 1 of the drawings illustrates only a
small portion of the overall apparatus which may be used in
monitoring, in response to light transmittance criteria, a chemical
reaction for determination of the presence of certain substances in
a discreet sample. The apparatus is particularly adapted for use in
the rapid and accurate evaluation of the presence (or absence) of
substances in a patient serum sample identifiable with an abnormal
condition. In the embodiment of the invention to be discussed below
there is a capability of sequentially identifying and monitoring
fourteen chemical reactions. Monitoring is carried out almost
simultaneously. These reactions are compared against a known sample
which is disposed in one of fifteen cuvette chambers. Any number of
cuvette chambers corresponding to the number of groupings of
radially spaced wells in the transfer disc may be provided as is
practical.
The FIG. 1 structure generally includes a housing having an upper
portion 12 providing a chamber 14. The rotor assembly 16 to be
described is disposed for movement within the chamber. A lower
housing portion 18 serves to enclose a shaft 20 which is received
in the upper housing. The shaft at one end is connected to the
rotor. Any means known to the art may be employed. The shaft at the
other end is coupled by suitable gear means to a drive motor (not
shown).
A collar 22 is supported by the housing members. To this end the
collar includes a radial flange 24 which is supported by shoulder
26 of the upper housing. A plurality of set screws 28, only one
being shown, circumferentially spaced about the flange are employed
to mount not only the collar as discussed but also connect the
upper and lower housings.
The collar member additionally provides an annular cutout 29 at
both the top and bottom. Bearing members 30 secured to the shaft
are disposed in each cutout for apparent purposes. Sealing members
32, likewise, are disposed in each cutout. The sealing members are
of cylindrical and generally L-shaped form. The base of each member
is cemented or otherwise mounted to the collar so that the extended
portion extends generally perpendicularly toward and into wiping
contact with the shaft 20. The sealing members serve to prevent
patient serum or reagent material from passing into the region of
the drive motor housing.
The rotor 16 includes a transfer disc 34 and a cuvette rotor 36. As
briefly discussed the cuvette rotor includes several chambers. Both
the transfer disc and the cuvette rotor are supported by a plate
38. The rotor additionally includes a top plate 40. The top plate
is of annular construction and includes an annular extending skirt
portion 42 for purposes hereinafter discussed. A plurality of
mounting screws 44 circumferentially spaced about the rotor
periphery connect together certain of the rotor components
including the cuvette rotor and the plates to permit rotary
movement of the rotor assembly within the upper housing. The
transfer disc is supported by the lower plate 38 and is readily
removable from within the annulus defined by the cuvette rotor.
As indicated, the apparatus is capable of the rapid and accurate
evaluation of reactions in which one of the reactants is blood
serum from a patient. The rate of reaction will normally be
evaluated over a period from time zero at which time the reactants
are first brought together to completion or the end point of the
reaction.
To accomplish the purpose of first isolating the reactants and then
quickly bringing them together the transfer disc in the upper
surface includes a plurality of pairs of radially spaced chambers
50, 52. In the present embodiment there are fifteen pairs of
chambers. Typically serum from a patient will be disposed in
chamber 52 while reagent will be disposed in chamber 50. Each
chamber of each group of chambers is internally loaded with a
finite and precise volume. Loading may be accomplished by any of
the known clinical techniques which are commonly employed.
The transfer disc may be constructed of any metal or plastic
material which is, among other factors, sturdy in use and not
deleteriously affected by patient serum or any one of the various
reagents used in testing for glucose, bilirubin, albumin, LDH
(lactic dehydrogenase), to name only a few of the well-known and
documented test procedures. While many metal or plastic materials
have been used successfully, a transfer disc formed of plastic,
such as polytetrafluoroethylene polymer, commonly referred to as
TEFLON is preferred. TEFLON is a registered trademark of E. I. du
Pont de Nemours and Company.
The transfer disc 34 includes a further well 54 constituting a
first mixing chamber. Thus, through rotation of the rotor assembly
and upon the development of centrifugal forces through rotation the
serum and reagent will transfer from their respective wells into
the mixing chamber 54. A port 56 in the wall of the transfer disc
serves to pass the reagents into an aligned cavity or chamber in
the cuvette rotor 36.
A cover assembly (not shown in full detail) is supported by the
housing to enclose the area of the wells 50, 52 and 54. The cover
assembly includes an inner cover 51 which, however, is shown in the
Figure. The inner cover provides generally a flat under surface and
a downwardly depending skirt portion to surround the outer
upstanding wall of the transfer disc in a loose fit. The remaining
components of the cover assembly may be supportingly received on
the housing over the inner cover by a hinge structure or equivalent
means and may be held in the closed position by a spring loaded
latch mechanism. An O-ring is suitably disposed between the cover
assembly and the wall at a shoulder in plate 40 to seal the chamber
area of the transfer disc from the chamber 14. Thus, the reagents
will entirely move through the port 56.
The cuvette rotor 36 will be discussed in greater detail below. For
the present discussion, however, suffice it to say that the
reagents are held captive and mixed in the cuvette chambers once
having entered the same during rotation of the rotor and the
developed centrifugal forces. Viewing windows 58 are positioned
both above and below the cuvette chambers. The viewing windows may
be of any optical material capable without significant absoprtion
of passing light both to the reagent sample within the cuvette
chambers and thereafter passing the light not absorbed by the
reagent to a photosensitive means. The viewing windows may be
plexiglass, pyrex glass or quartz, for example. The viewing windows
in the preferred embodiment are formed of quartz. One reason is
that quartz windows will permit ultraviolet measurement. Both
viewing windows are annular in outline.
The overall apparatus functions to compare the analog response to
the amount of light transmittance from one of several cuvette
chambers with the criteria from the reference cuvette chamber.
However, the readout preferably is in digital form. Therefore, the
output of a photoresponsive means, such as a photomultiplier 60,
which is proportional to the value of light transmittance of the
reagent within the cuvette chamber, is converted into a digital
output reading and compared in a computer with the digital output
reading indicative of a sample.
As illustrated in FIG. 1 light from a source (not shown) is
reflected by mirror 62 toward the photomultiplier tube. The
photomultiplier tube is supported within a housing 64. The housing
except for the light slot 66 is completely enclosed to prevent
stray light from impinging on the photoresponsive tube. As
apparent, the lower housing and the rotor plates each provide a
path for light along the path (illustrated by arrow 68) from the
mirror 62 to and through the housing slot 66. Each plate preferably
provides a plurality of apertures disposed in alignment with each
of the several cuvette chambers.
The apparatus may be utilized in the conduct of any one or more of
the many known tests performed on patient serum. Generally, the
individual test results will require utilization of light at
different frequencies. To this end the housing may accommodate a
filter of the chosen frequency. It is also contemplated that a
monochromated light may be used. A plate 72 including a central
aperture is supported by the housing and in turn supports the
filter. Typically, provision will be made for replacement of one
filter for another, as required by the particular test.
The cover (not shown) may be apertured within a central region. A
seal and bearing structure may be disposed in the aperture. The
structure may be positioned in abutting relation to the end of
shaft 20 to provide a bearing surface for shaft rotation. The seal
functions to permit communication both of air under pressure and
wash solution from an external source to an upper hollow portion of
the shaft. The hollowed portion of the shaft includes a
multiplicity of spaced radial holes, one of which is preferably
directed toward each cuvette chamber. During the period when the
reaction is monitored air may be drawn through the seal and shaft
into the cuvette chamber by a vacuum created along the path of
siphon from the cuvette chamber. The air aids in the complete
mixing of serum sample and reagent.
Generally, the information received by the computer is stored
according to its program. Thereafter, consistent with the computer
program a digital readout is provided. When the data retrieval
phase of the operation has been completed each cuvette chamber is
pressurized by air pressure from the external source causing a
siphoning of liquids from the cuvette chambers. The liquids,
referring to FIG. 1 are siphoned into the chamber 14 and through
housing opening 80 to a waste collection point. The cuvette
chambers are thereafter washed, rinsed, centrifuged and blown clear
in like manner to condition the rotor assembly for a subsequent
test procedure. It is to be noted that a siphoning action will
commence only with the application of air under pressure greater
than the centrifugal forces acting on the liquids in the cuvette
chamber during rotation. The skirt 42 serves substantially to
prevent an aerosol from the liquids being siphoned being formed
within the chamber. Such an aerosol may pass to the inner confines
of the chamber or merely collect as a contaminant within the
chamber.
The cuvette rotor 36 may be seen to best advantage in FIGS. 2 and 4
of the drawings. The rotor is in the form of an annulus 100 having
a plurality of indentations defining individual chambers 102 which
are equidistantly spaced one from the other. In the preferred
embodiment there are fifteen chambers, each disposed radially of
the wells 50, 52 and 54 in the transfer disc 34.
The cuvette rotor is formed of a material which may be cast, milled
or otherwise shaped to the configuration as shown in the Figures.
Either plastic materials or metal may be utilized. Choice of
material is dependent upon certain factors. To this end, the
material must at least be of high thermal conductivity to display
good heat transfer capability, it must also be inert so as not to
react with those liquids which will contact its surfaces during
operation, it preferably should display low surface energy
characteristics, it should be subject to machining thereby to
provide an extremely smooth surface to prevent adherence of
chemical matter in any irregularity, and it must be easily and
completely cleanable. The cuvette rotor is preferably formed of
either an aluminum or brass substrate and thereafter coated with a
thin film, i.e., about 0.005 inch in thickness. The film includes
an application of electrodeless nickel and an outer layer of gold
electroplated thereon.
It is contemplated, also, that various plastics may be used in
substitution for the nickel and gold layer. These plastics include
TEFLON, polymers of trifluorochloroethylene (KEL-F) and vinylidene
fluoride resins (KYNAR). KEL-F and KYNAR are registered trademarks
of M. W. Kellogg Company and Pennsalt Chemicals Corporation,
respectively. These materials display low surface energy
characteristics, are capable of undergoing machining or polishing
to a smooth surface and may be deposited on the aluminum or brass
substrate in a thickness on the order of 0.005 inch. The thickness
of the plastic is such that the characteristic of heat transfer
from the substrate to the liquids in the cuvette chamber is not
significantly diminished. The plastics are also inert to the
liquids in the cuvette chambers such to display immunity to protein
adhesion on the walls of the chambers.
The heater structure is disposed within the substrate. More
particularly, the substrate is cut out within the lower surface and
the area bounded by the circular line 104 and the line 106 to a
depth of approximately 0.0070 inch. The area of the cutout and
consequently the area of the heater is significant with respect to
the total surface area of the substrate. By this relationship, a
high ratio of heater area to surface area is provided. The heater
structure is in the form of a printed circuit. A layer of
insulation, such as a glass-filled TEFLON (KAPTON), a tradename of
The Connecticut Hard Rubber Company or an equivalent insulation
material, such as fiberglass cloth with a nitrile rubber filler and
binder, may be both disposed on the outer side of the heater. The
insulated printer heater circuit is bonded to the substrate by any
one of the many adhesive materials. The entire heating package may
be on the order of 0.008 inch in thickness.
A connector 108 is supported within the substrate for electrical
connection of the resistance heater to a source of power. A
temperature sensing element which may be a thermistor 110 is
supported within the substrate. A connector 112 supports the
thermistor within an aperture in the substrate. The thermistor
extends toward a single one of the many chambers 102. The
thermistor preferably is disposed relatively closely to both the
wall of the chamber and the resistance heater so that the sensor
probe will rapidly detect a low temperature condition of the
chamber liquids to cause automatic increase in heater output. The
sensor, likewise, will rapidly react to high temperature in the
chamber liquids to automatically control or stop heater output.
Preferably the sensor will be disposed approximately 0.125 inch
from both the resistance heater and the wall of the chambers
102.
A siphon 114 is formed within the upper surface communicating the
outer periphery of the annulus with each of the several chambers
102 throughout a general S-shaped path. The depth of the path will
be about 0.040 .+-. 0.002 inch. As heretofore discussed, the
centrifugal force exerted on the reactants within the chambers 102
because of rotation of the rotor is not sufficient to cause the
reactants to exit the chamber by way of the siphon. As also
discussed, air under pressure from an external source is introduced
to the several chambers for the purpose of first evacuating the
chamber of reacting liquids and thereafter of wash solutions
introduced thereto. The rear wall of the chambers are inclined at
116 (see FIG. 4) to aid in movement of the liquids toward the
entrance to the respective siphon.
Referring again to FIG. 4 it will be noted that the surface of the
annulus within the space generally between the consecutive chambers
is cutout at locations 118 and 120. The relief throughout the upper
surface will be approximately 0.025 inch. The relieved area
throughout the upper surface serves to reduce the overall weight of
the cuvette rotor annulus.
FIG. 3 illustrates the several component parts defining the rotor
16. In this connection the Figure illustrates the transfer disc 34
and cuvette rotor 36 in surrounding relation. A gasket member 130
is supported on opposed sides of the cuvette rotor. One gasket
provides a support surface for the upper annular optical piece 58
and together with the piece serves to provide an upper seal for
each chamber 102. The gasket may be bonded to the optical piece by
any means, such as a room temperature vulcanizing medium of nitrile
or silicone rubber. The second gasket serves a like function when
disposed between the lower surface and the lower optical piece and
likewise may be bonded to the optical piece. The relieved surface
area together with the wall adjacent the path of the siphon
provides a ridge upon which the gasket 130 is disposed. The ridge
enhances the seal obtained between the substrate and the upper
optical piece.
Each gasket 130 is configured to provide a constant radial
perimeter and an inner contour which duplicates the outline of the
wall bounding each chamber and between chambers. The diameter of
the gasket will be equal to the outer diameter of the annular
optical pieces. The diameter is slightly in excess of the diameter
of the outside wall of the relieved area 118.
A second pair of gaskets 132, both of annular form and having an
outer diameter equal to the outer diameter of the gaskets 130 are
disposed on the other sides of the optical pieces 58. Each gasket
includes a plurality of apertures which are equidistantly spaced to
permit the passage of light along the path 68. The inner diameter
of gaskets 132 will be generally equal to the inner diameter of
both the optical pieces 58 and the cuvette rotor 36. Both the
gaskets 130 and 132 may be formed of any one of neoprene, Buna-N or
silicone rubber. As heretofore stated, the total cycle of the
apparatus requires a washing and cleaning stage as well as a stage
during which liquids within the cuvette chamber are expelled. These
operations utilize air pressure thereby to pressurize each chamber.
The force exerts special stress on the liquid sealing areas, for
example, the seal between the cuvette rotor and the optical window.
Thus, the seal must be liquid and air tight to at least a value of
25 pounds per square inch. The material of the seal is also
resistant to cold flow and any deformation as a result of constant
temperature recycling. They are also resistant to chemical
interaction with blood components.
An annular foil element 136 duplicating the shape of gasket 132 is
disposed between the gasket and the upper optical piece. The foil
may be formed of gold or aluminum and serves the function of
dissipating any build-up of a static electrical charge on the
optical member. The charge may develop and accumulate on the upper
optical surface because of friction associated with the rotating
parts. No static electrical charge will build on the lower optical
surface because of the continual liquid contact therewith. The foil
through any particular means (not shown) is grounded thereby
bleeding the electrical potential substantially to prevent the
adherence of airborne particles on the optical surface at the
cuvette chamber.
The structure as discussed above is sandwiched together and secured
between the lower rotor plate 38 and the upper annular plate 40. To
this end the cuvette rotor includes a plurality of holes 140
through which the mounting screws 44 are received.
A typical circuit may be seen in FIG. 7. The circuit provides in
series through connectors 108 and 112 connection of the resistance
heater 122 and the thermistor 110. Electro-mechanical slip ring
structure (not shown) may be utilized to couple the series
components to electrical power.
In operation, precise volumes of patient serum and reagent are
dispensed or otherwise disposed in the wells 50 and 52 prior to the
commencement of any program of operation. An additional reagent may
be dispensed or disposed in the well 54, if desired. Upon
commencement of rotation of the rotor, which may attain a speed of
up to 3,000 rpm, the serum and reagent(s) are rapidly propelled
generally outwardly toward the well 54 and port 56 undergoing some
mixing prior to entering the cuvette chamber which with the optical
members form an optical cell. Since mixing of liquids has commenced
and thereafter continues in the optical cell it is imperative that
the liquids be quickly brought to the optimum temperature. This has
been discussed. The apparatus may operate in accordance with a fast
rate over approximately 96 seconds during which absorbance readings
are printed and displayed every 3 seconds or in accordance with a
slow rate over approximately 8 minutes during which absorbance
readings are printed and displayed every 15 seconds. Light from a
source is reflected along the axis of the optical cell toward the
photoresponsive device. The optical members are approximately 5 mm
in thickness and are of a material which will pass substantially
all source light to the optical cell and that light passing through
optical cell to the photoresponsive device. Thus, the amount of
absorbance or transmittance will be determined by the liquid in the
optical cell. After the reaction is complete the liquids are
expelled from the optical cells by the introduction of air
pressure. A washing and cleaning cycle may be employed preparatory
to a subsequent test. For this purpose both wash solution and
thereafter air under pressure is introduced to the chamber of the
transfer disc to clean the same through rotation, expell the
liquids and dry the chamber walls.
* * * * *