U.S. patent number 3,798,459 [Application Number 05/295,780] was granted by the patent office on 1974-03-19 for compact dynamic multistation photometer utilizing disposable cuvette rotor.
This patent grant is currently assigned to The United States of America as represented by the United States Atomic. Invention is credited to Norman G. Anderson, Carl A. Burtis, Wayne F. Johnson, James C. Mailen, Charles D. Scott.
United States Patent |
3,798,459 |
Anderson , et al. |
March 19, 1974 |
COMPACT DYNAMIC MULTISTATION PHOTOMETER UTILIZING DISPOSABLE
CUVETTE ROTOR
Abstract
A compact analytical photometer of the rotary cuvette type
designed to use small disposable cuvette rotors. A power driven
cuvette rotor holder having a generally flat, circular
configuration is provided with an integral, upstanding, annular lip
for receiving, in an easily insertable and removable fashion, small
disposable cuvette rotors. A series of axially extending apertures
are disposed in a circular array through the rotor holder in axial
alignment with respective cuvettes in the rotor to permit light to
be transmitted through the cuvettes as the rotor holder and cuvette
rotor rotate between a stationary light source and photodetector.
Additional apertures extend through the rotor holder near its
periphery to permit light passage through the rotor holder for
rotor and cuvette synchronization purposes. Movable rotor and
cuvette synchronization detectors are positioned along the
periphery of the rotor holder for generating signals which are used
to synchronize the photometer output with a computer and to provide
rotor speed control. Rapid deceleration of the rotor holder and
rotor for sample mixing purposes is accomplished by braking means
engaging the rotor holder drive shaft.
Inventors: |
Anderson; Norman G. (Oak Ridge,
TN), Burtis; Carl A. (Knoxville, TN), Johnson; Wayne
F. (Loudon, TN), Mailen; James C. (Oak Ridge, TN),
Scott; Charles D. (Oak Ridge, TN) |
Assignee: |
The United States of America as
represented by the United States Atomic (Washington,
DC)
|
Family
ID: |
23139207 |
Appl.
No.: |
05/295,780 |
Filed: |
October 6, 1972 |
Current U.S.
Class: |
250/576; 250/303;
356/428 |
Current CPC
Class: |
G01N
21/07 (20130101) |
Current International
Class: |
G01N
21/07 (20060101); G01N 21/03 (20060101); G01n
021/26 () |
Field of
Search: |
;250/218,16R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dixon; Harold A.
Attorney, Agent or Firm: Horan; John A.
Claims
What is claimed is:
1. A compact fast analyzer of the rotory cuvette type
comprising:
a. a power-driven cuvette rotor holder comprising a flat circular
base, an annular, upstanding retaining rim integrally fixed to said
base, and an axially extending upstanding pin fixed to said base
within the radial confine of said rim; said base defining:
i. a first series of axially extending apertures disposed in a
circular array through said base within the radial confine of said
rim.
ii. a second series of axially extending apertures disposed in a
circular array through said base without the radial confine of said
rim, said apertures in said second series of apertures being equal
in number to said apertures in said first series of apertures;
b. a removable cuvette rotor having a circular plate-like
configuration disposed on said base within the confine of said rim,
said rotor having an opening for receiving said pin and, defining a
circular array of sample analysis cuvettes in axial register with
respective apertures in said first series of apertures;
c. a adjustable light source disposed above said cuvette rotor for
providing a beam of light incident on said rotor assembly at a
point corresponding to the radial position of said sample analysis
cuvettes;
d. means for detecting light from said light source after it has
passed through said sample analysis cuvettes, said means for
detecting light generating an output signal proportional to the
intensity of light detected; and
e. signal generating means disposed adjacent said rotor holder for
detecting the passage of apertures in said second series of
apertures.
2. The fast analyzer of claim 1 wherein an adjustable filter holder
containing a plurality of absorbance filters extends between said
base and said means for detecting light from said light source
after it has passed through said sample analysis cuvettes.
3. The fast analyzer of claim 1 further including means for rapidly
braking rotation of said rotor holder and rotor.
4. The fast analyzer of claim 1 further including a thermistor
mounted within said upstanding pin for measuring the temperature of
said cuvette rotor, and electrical slip rings in electrical
communication with said thermistor affixed to said rotor
holder.
5. The fast analyzer of claim 4 wherein said upstanding pin is
located at a radial position corresponding to the radius of said
first series of axially extending apertures and said sample
analysis cuvettes, and wherein said thermistor is within said pin
so as to be axially centered within said removable cuvette rotor
when said rotor is disposed on said base within the confine of said
rim.
6. The fast analyzer of claim 1 wherein said removable cuvette
rotor defines:
a. first and second sets of radially oriented loading cavities
disposed in concentric annular arrays; and
b. means for effecting centrifugal passage of fluid from said first
and second sets of loading cavities to respective cuvettes in said
circular array of sample analysis cuvettes.
7. The fast analyzer of claim 6 wherein said cuvette rotor is of
laminated construction with a central opaque disk sandwiched
between first and second transparent disks, said sets of first and
second cavities comprising depressions in said opaque disk, and
loading apertures being provided through said first transparent
disk in axial register with respective cavities in said first and
second sets of loading cavities.
8. The fast analyzer of claim 6 wherein said cuvette rotor further
defines a central distribution chamber and a plurality of
distribution passageways communicating between said distribution
chamber and respective cuvettes in said circular array of sample
analysis cuvettes.
9. The fast analyzer of claim 8 wherein each of said distribution
passageways intersects with adjacent distribution passageways at an
acute angle so as to form a serrated periphery about said
distribution chamber.
Description
BACKGROUND OF THE INVENTION
The invention described herein relates generally to photometers of
the rotary cuvette type and more particularly to a compact
photometer utilizing disposable cuvette rotors. It was made in the
course of, or under, a contract with the U. S. Atomic Energy
Commission.
A representative fast photometric analyzer of the rotary cuvette
type is described in U. S. Pat. No. 3,555,284, issued to common
assignee on Jan. 12, 1971. In the fast analyzer described in that
patent, centrifugal force is used to transfer and mix samples and
reagents in a multi-cuvette rotor. A stationary photometer scans
the cuvettes during rotation. The signals thus generated are
evaluated by a computer, allowing the reactions taking place in the
respective cuvettes to be observed as they occur. Since all
reactions are initiated simultaneously and are coupled with the
continuous referencing of the spectrophotometric system of the
analyzer, errors due to the electronic, mechanical, or chemical
drift are minimized.
Although analyzers built in accordance with the aforementioned
patent have been highly successful in that they operate with
relatively low sample and reagent volume requirements, have
demonstrated a high sample analysis rate, and are subject to
automated operation, further improvement is desirable. For example,
the cuvette rotor described in that patent is a relatively large
and complex structure of glass and polytetrafluorethylene rings
sandwiched together and secured between a steel rotor body and
bolted flange ring. Such rotors are expensive and must be cleaned
between analytical runs to avoid contamination of subsequent
samples. Correspondingly large cabinetry, drive motors, etc., must
be used with the rotor with the result that the fast analyzer is
not truly portable and requires a relatively large amount of
valuable laboratory space.
A further reduction in sample and reagent volume requirements is
also desirable. Savings of expensive reagents would result from
such a reduction in volume requirements. Also, the analyzer could
be used in testing applications where it is difficult to obtain a
sufficient volume of sample for analysis. For example, a greatly
reduced sample volume requirement would facilitate operation in a
pediatric laboratory where several analyses could be performed on
the small volume of blood obtained from the finger or toe-prick of
a newborn infant.
It is also desirable to make the cuvette rotors disposable to avoid
the possibility of sample contamination and to permit preloading of
standardized reagents. Such disposability would require the cuvette
rotor to be simple and inexpensive to construct and easily inserted
and removed from the analyzer following an analytical run.
It is, accordingly, a general object of the invention to provide a
compact analytical photometer of the rotary cuvette type.
Another, more particular, object of the invention is to provide a
compact analytical photometer of the rotary cuvette type which uses
small disposable cuvette rotors.
Other objects of the invention will be apparent upon examination of
the following description of the invention and the appended
drawings.
SUMMARY OF THE INVENTION
In accordance with the invention, a compact analytical photometer
of the rotary cuvette type is provided which is especially designed
to use small disposable cuvette rotors. A power driven cuvette
rotor holder having a generally flat, circular configuration is
provided with an integral, upstanding, annular lip for receiving,
in an easily insertable and removable fashion, small disposable
cuvette rotors. A circular array of axially extending apertures
extend through the rotor holder in axial alignment with respective
cuvettes in the rotor to permit light to be transmitted axially
through the cuvettes as the cuvette rotor and rotor holder rotate
between a stationary light source and photodetector.
Synchronization apertures extend through the rotor holder near its
periphery to permit light passage through the rotor holder for
rotor and cuvette synchronication purposes. Rotor and cuvette
synchronization detectors are positioned along the periphery of the
rotor holder for generating signals which are used to synchronize
the photometer output with a computer and to provide rotor speed
control. Rapid deceleration of the rotor holder and rotor for
sample mixing purposes is accomplished by braking means engaging
the rotor holder drive shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view, partially cut away, of a photometer made
in accordance wtih the invention.
FIG. 2 is a vertical section view of the photometer of FIG. 1.
FIG. 3 is an enlarged plan view showing the static loading side of
a disposable cuvette rotor for use in the photometer of FIGS. 1 and
2.
FIG. 4 is an enlarged isometric view, sectioned and partially cut
away, further illustrating the static loading side of the cuvette
rotor of FIG. 3.
FIG. 5 is an enlarged plan view, showing the dynamic loading side
of the cuvette rotor of FIGS. 3 and 4.
FIG. 6 is an enlarged isometric view, sectioned and partially cut
away, further illustrating the dynamic loading side of the cuvette
rotor of FIGS. 3 to 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the drawings, initially to FIGS. 1 and 2, a
compact photometric analyzer is shown in a top plan view and in
vertical section, respectively. Rotatably mounted on top of a
small, generally rectangular, sheet metal cabinet 1 is a
power-driven cuvette rotor holder 2 having a flat, plate-like,
circular base 3 with an integral, upstanding, annular lip or rim 4
for receiving and retaining a disposable cuvette rotor 5. Two or
more retaining pins 6 (only one shown) are fixed to rotor holder 2
within the confines of lip 4 and engage mating recesses in cuvette
rotor 5. Pins 6 prevent relative rotation of the cuvette rotor and
rotor holder during operation of the analyzer under conditions of
high rotary acceleration, while permitting relatively effortless
manual insertion or removal of the cuvette rotor under static
conditions. A circular array of apertures 7 extends through base 3
of the rotor holder in axial register with respective sample
analysis cuvettes 8 within cuvette rotor 5.
A movable photometric light source 9 provides a light beam of
constant intensity interesecting rotor 5 at a point corresponding
to the radial positions of sample analysis cuvettes 8. The light
beam from source 9, indicated by a broken line in FIG. 2, is
aligned in such a manner so as to be transmitted through each
aperture 7 and cuvette 8 as they are rotated through the beam.
Light source 9 includes a quartz-iodine incandescent lamp 10, a
finned lamp housing 11, and a set of focusing lenses 12. Knob 14 is
attached to housing 11 to facilitate positioning of the lamp
housing during or immediately following analyzer operation when the
housing is at an elevated temperature due to the heat generated by
lamp 10.
An electronic photodetector 15 is disposed below rotor holder 2 and
the top of cabinet 1 where it is positioned to receive light
transmitted through sample analysis cuvettes 8 as they pass between
the photodetector and light source 9. Photodetector 15 comprises a
photomultiplier tube which provides an output signal proportional
to the intensity of the light which it receives.
Interposed between photodetector 15 and rotor holder 2 is a movable
filter holder 16 which permits the selective positioning of one of
a plurality of interference filters 17 in the path of the light
transmitted through cuvettes 8. Filter holder 16 is fixed, by means
of a set screw, to vertically extending shaft 18 which is rotatably
supported by a roller thrust bearing 19 fixed within the base of
fixture 20. Fixture 20, which is rigidly fixed to cabinet 1, is
slotted to permit angular displacement of filter holder 16 within
the limits necessary to align any of filters 17 above photodetector
15. A filter selector knob 22 is fixed to the top end of shaft 18
to enable an operator to manually select the filter desired.
As shown in FIG. 2, a thin-walled tube 23 serve as a mounting post
for movable light source 9. Tube 23 is attached to and supported
within fixture 20 by means of a set screw and extends coaxially
with shaft 18. Rotatably engaging tube 23 immediately above fixture
20 is a first sleeve 24. A second sleeve 25, which serves as a
mounting fixture for lamp housing 11, is fixed to first sleeve 24
by set screw means and is rotatable therewith. First sleeve 24 is
provided with depressions 26 (only one shown) which are engaged by
spring loaded detent 27 when the light source is in operating
position as shown or swung away 90.degree. for rotor replacement as
indicated in phantom in FIG. 1. Radial adjustment of the light
source to align it with the cuvettes is accomplished by loosening
set screw 28 and sliding adjustment sleeve 29 within opening 30 in
second sleeve 25. An indicator plate 32, which together with filter
selector knob 22 shows the position of filter holder 16, is fixed
to the top of tube 23 by set screw means. A spring loaded detent in
knob 22 engages depressions in indicator plate 32 to provide
positive positioning of the filter holder.
Fixed to the bottom of shaft 18 is an index wheel 33 engaging a
micro switch 34. Rotation of shaft 13 during a filter selection
operation causes a corresponding rotation of the index wheel and
activation of the micro switch. This causes a different preset
potentiometer to be connected into the photodetector high voltage
supply circuit in order to maintain a constant signal from a
reference cuvette filled with a water blank. A different preset
potentiometer is used for each interference filter 17 in filter
holder 16.
An alternative method for maintaining a constant output from the
photodetector is described in copending application of common
assignee Ser. No. 289,906 filed Sept. 18, 1972. According to that
method, the signal level from the reference cuvette is compared
with a preset desired level and adjustments to the high voltage
photodetector supply made as needed by appropriate control
circuitry to maintain the desired output. Drift in the
photomultiplier tube and associated circuitry is also compensated
for.
The rotor holder and cuvette rotor are rotatably driven by a
combination servomotor-tachometer generator 35. A magnetic brake 36
acts on the rotor holder drive shaft 37 to provide rapid braking
action to the cuvette rotor to enhance sample and reagent mixing in
the cuvettes. Braking from a rotor speed of about 2,000 rpm to a
standstill in less than 1 second has been achieved using magnetic
brake 36.
Synchronization signals are provided by rotor and cuvette
synchronization detectors 38 and 39, respectively. A similarly
constructed detector 40 provides a signal for activating the
automatic photomultiplier voltage control (not shown). Signals are
generated when appropriately spaced apertures in the rotor holder
pass through the detectors and allow light from a small tungsten
incandescent lamp 41 disposed in the detector above the rotor
holder to reach a photodiode 42 disposed in the detector below the
cuvette holder. Detector 39, shown in section in FIG. 2, is
representative of all three detectors. A circular track 44 for
positioning the detectors partially encircles cuvette holder 2.
Synchronization may be adjusted by moving the detectors along track
44 until proper synchronization is obtained and then securing them
to the cabinet with locking screws.
As shown in FIG. 1, a circular array of synchronization apertures
45 is provided in rotor holder 2 to generate a signal in detector
39 just after each cuvette passes between light source 9 and
photodetector 15. Single apertures 46 and 47 cause signals to be
generated in detectors 38 and 40, respectively, on each revolution
of the rotor holder.
The temperature of cuvette rotor 5 is monitored by means of a
thermistor within retaining pin 6 which is positioned to extend
between two cuvettes on a common radius with the circular array of
cuvettes. The thermistor is further positioned within pin 6 so as
to be axially centered within rotor 5. Such positioning provides a
close correlation between the output of the thermistor and the
temperature of the cuvettes. Slip rings 48 in electrical
communication with the thermistor are provided on the rotor holder
for reading the signal from the thermistor. The rotor temperature
and speed are both read from one meter 49 mounted on top of the
analyzer cabinet.
Referring now to FIGS. 3 and 4, the static loading side of the
disposable cuvette rotor 5 used in the analyzer of FIGS. 1 and 2 is
illustrated in plan and sectioned isometric views, respectively. In
construction, the rotor is of laminated design with a central,
preferably opaque, plastic disk 51 sandwiched between outer
transparent disks 52 and 53. A circular array of axially extending
apertures are provided in disk 51 to serve as sample analysis
cuvettes 8. Concentric annular arrays of sample and reagent loading
cavities 54 and 55 are disposed on a one-to-one basis along radii
passing through each cuvette. As shown in FIG. 4, loading cavities
54 and 55 are formed from depressions in central disk 51 and are
closed by outer disk 52. Loading apertures 56 and 57 are provided
in disk 52 in register with each cavity in the respective arrays of
loading cavities. Static loading of reagents and samples through
the loading apertures is possible using a hypodermic syringe or
automated dispensing equipment. Radial liquid communication is
provided by means of small connecting passageways 58 and 59 between
respective sets of loading cavities and cuvettes. A central loading
port 60 extends through disks 51 and 52 to permit dynamic loading
of liquids using the dynamic loading side of the rotor described
below in reference to FIGS. 5 and 6.
Plan and perspective views of the dynamic loading side of rotor 5
are shown in FIGS. 5 and 6, respectively. Loading port 60
terminates in a distribution chamber 61 which communicates with
cuvettes 8 through radially extending distribution passageways 62
which are of capillary size to retain liquids in the cuvette when
the rotor is not spinning. The intersection of passageways 62
creates a saw-tooth or serrated edge effect which provides a
substantially equal distribution of liquid into the respective
passageways when rotor 5 is rotating and liquid is injected through
port 60 into the distribution chamber.
Several methods of loading sample and reagent liquids in rotor 5
are possible. One method involves static loading of individual
samples and reagents in respective loading cavities 54 and 55. This
is accomplished by inserting the sample and reagent volumes through
respective loading apertures 56 and 57. Great flexibility is
possible using this method since different combinations of samples
and reagents are possible in each set of loading cavities. Rotation
of the rotor following static loading effects transfer of the
sample and reagent liquids into respective cuvettes for photometric
analysis.
Another method of loading may be used where it is desired to either
react a plurality of reagents with a single sample or a single
reagent with a plurality of samples. In that case, the single
sample or reagent is injected through loading port 60 into the
spinning rotor and distributed equally to the cuvettes. The rotor
is then brought to a standstill and individual sample or reagent
loadings are made from the static loading side of the rotor.
Still another method of loading involves the preloading and
lyophilization of different reagents in the respective cuvettes.
When a photometric analysis is to be made, the lyophilized reagents
are solubilized by injecting water or buffer into the spinning
rotor in the manner described above. Sample fluid may be likewise
dynamically loaded to obtain multiple chemical analyses on a single
blood sample.
The above description of one embodiment of the invention should not
be interpreted in a limiting sense. For example, the rotor may have
a different number of sample analysis cuvettes than the 17 shown.
Also, the particular arrangement of passageways for static and
dynamic loading could be modified and/or omitted in part so that
only static or dynamic loading would be possible. It is intended,
rather, that the invention be limited only by the scope of the
appended claims.
* * * * *