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Apparatus for monitoring chemical reactions and employing moving photometer means


Publication number
CA1138221A CA 391039 CA391039A CA1138221A CA 1138221 A CA1138221 A CA 1138221A CA 391039 CA391039 CA 391039 CA 391039 A CA391039 A CA 391039A CA 1138221 A CA1138221 A CA 1138221A
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Patent type
Prior art keywords
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Application number
CA 391039
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French (fr)
Thomas Horne
Guenter Ginsberg
Robert L. Kreiselman
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Coulter Electronics Inc
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Coulter Electronics Inc
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Apparatus for measuring progressively the absorbance changes of a large number of aliquots from a plurality of different samples. The sample introduction, testing instructions, aliquot preparation, reagent dispensing, absorbance measuring and data recording all can be accomplished in a continuous mode of processing. Stat and batch operation also can be accomplished. The aliquots are in an array of cuvettes which is advanced slowly along a circular path.
Photometer means, preferably having several photometric detectors, are mounted in fixed orientation on a common support that advances rapidly along a similar circular path, such that radiation passing through each of the cuvettes is monitored many times by a specific photometric detector by the time that cuvette completes one circuit of its path. The photometric detectors can operate at several different wavelengths. Many different chemical reactions can be monitored at the same time, The radiant energy passing through each cuvette is received by the continuously moving photometer means, is converted electrically into a digitized value proportional to absorbance and is transmitted digitally from the moving assemblage of photometric detectors, cuvettes and electrical components to a stationary receiver. In one embodiment, the digital transmission is in the form of a pulsed train of light signals. In another embodiment, one or more slip rings transmit electric signals from the moving assemblage to the stationary portion. Suitable drive elements, sample and reagent storage and transfer mechanisms as well as cuvette laundry means may be provided as part of the complete apparatus.


1~.38'~Zl This invention relates to apparatus for monitoring repeatedly the absorption of electromagnetic radiation by a plurality o~ specimens occurring during a period of time.
More particularly, this invention concerns an apparatus by which each of a plurality of samples provides a plurality o~
aliquots which can be subjected to chemical reaction with different reagents. The absorbance of each aliquot repeatedly is measured during a predetermined reaction time. The inputting of the samples, obtaining their aliquots, selecting and adding of reagents, and the absorbance measuring all can be effected in a continuous mode as well as a stat and a batch mode of operation. The term "ali~uot" as employed herein is a noun meaning a portion of a sample.
Apparatus described hereinafter would be well suited for the measurement of kinetic reactions such as useful in enzyme analysis as well as end point measurement. Many chemical reactions require from a few seconds to many minutes to be completed and, during such kinetic reaction time, it is often important to observe the progress of the reaction by making measurements several times One form of measùrement is ascertaining the absorbance of electromagnetic radiation of a particular wavelength by the analyte. Typically, enzyme reaction measurements have been accomplished by batch handling methods and apparatuses re~uiring a considerable amount of preparation and manipulation by the laboratory technician. The nature of the process cannot help but result in relatively low throughput.

The disadvantages of the previous proposals may be over-come by progressively measuring absorbance changes in sample aliquots in a plurality of cuvettes arran~ed in a circular ar-ray which is rotated in a slow or step-by-stcp motion. ~s the cuvettes are advanced sample aliquots are introduced into each cuvette in a first position, each aliqu~t is prepared for a specific test by adding one or more reagents and the absorb-ance changes are monitored by a plurality of photometers ro-tating at a greater speed than the cuvettes and arranged to direct radiant energy through each cuvette as each photometer passes the cuvette and individually to generate an e] signal proportional to the instantaneous absorbance of the particular aliquot at one of a plurality of wavelengths of interest. Each aliquot is monitored numerous times by each photometer befor~ making a complete ci.r~uit ~nd e~ch s.ignal i.s converted from an analog to a digi.tal s~ al before it is trans-mitted from the rotating photometers to a stationary control receiver or computer. Prior to arriving at the first position after a complete circuit the tested a].i-luot i.s removed from 2C each cuvette which is then laundered so it is in conditi.on to receive the next sample aliquot. In this manner there i.s al-ways an endless array of cuvettes ready to receive the aliquots to be tested.
The preferred embodiments of this invention will now be described, by way of example, with reference to the drawings accompanying this specification in which:
FIG. 1 is a perspective somewhat diagrammatic view of one embodiment of the complete apparatus of the invention;
FIG. 2 is a fragmentary perspective view of the cuvette 113~ZZl turntable and the photometer rotor illustrating one embodiment of the photometer means, portions being shown in section and other portions being broken away;
Figure 3 is a median fraymentary sectional view through the data generating components of the apparatus further detailing the embodiment of Figure 2;
Figure 4 is a view similar to that of Figure 3, but detailing a second embodiment of the photometer means and a second embodiment of the data transmission arrangement;

ZZl C_ Figure 4a is a fragmentary view of a portion of Figure 4 but: illustrating a modified form of the invention utilizing a split beam arrangement; and Figure 5 is an electrical block diagram primarily of the portions of the apparatus concerned with the generation and transmission of digitized absorbance data.
with reference to Figures 1 and 5 which are somewhat diagrammatic, the subject apparatus can be composed of a control console 10 and a chemistry processing portion 12. Input information, concerning each sample and the different chemical tests to be performed on aliquots of each specific sample, can be supplied by way of a keyboard 14 and/or data cards fed into a receiver 16 of suitable data input means 18. The input information then is applied to a master control unit 20, which has many functions, only some of which will be mentioned hereinafter, but those skilled in the art will appreciate the more complete control ambit of this unit. A first function of the master control unit 20 can be to feed the input information to a readout unit 22, which can include a visual display 24 and ~0 a printer of a tape 26, from which the operator can verify that the input information has been entered accurately.
The master control unit 20 can store a list of commands pertinent to each of the chemistry tests that the apparatus is capable of performing. Thus, when the input information '5 associates a specific sample with a specific set of tests, and assuming the apparatus has needed diluent and reagents, all that remains to be accomplished by the human operator is to have placed the sample into an appropriate one of the sample holders _ ~ _ 1~38;2Zl 28 in a sample disc 30. Thereupon, the master control unit 20 can control the transferring of sample aliquots into cuvet-tes 32 mounted in an annular array in a turntable which is par~ of the data generating portion 34. An aliquot and diluent transfer S mechanism 36, orms of which are known, can accomplish the transferring, with each required chemistry test being associated with an identified cuvette 32 for that specific sample. As the several aliquots are being dispensed, the cuvette array will be indexed forward one step for each cuvette and its associated aliquot. As used herein~ "step" and "indexed"
include but are not limited to discrete movements, since the cuvette array could be continuously moving slowly.
A reagent supply area 38 has separate reagent containers 40 in a reagent disc 42, First and second reagent dispensers 44 and 46 will add appropriate reagents to specific cuvettes as those cuvettes advance around the path of movement of the annular array. The dispensing point of the first reagent dispenser relative to the cuvette path is spaced several steps prior to that of the second dispenser 46 so that in this space interval, which corresponds to a known time interval, the first reagent can have reacted with an aliquot prior to the introduction of the second reagent. Some chemical tests may require the addition of reagent from only one of the dispensers The aliquot and diluent transfer mechanism 36 as well as the reagent dispensers 44 and 46 can be of the type which swing arcuately between the source of fluid 28 or 40 and a cuvette 32, Both when receiving and dispensing fluid the probe of the dispensers can move down into the vessels 28, 32 and 40, but would be elevated to be able to s~ing free thereof in an _ S

arcuate path.
Between the time and position that the aliquot is dis-pensed and the first reagent is dispensed there is a distance along the path of the cuvettes durin~ which measurement of the transmittance of the aliquot with its diluent ancl ~he cuvette walls can be accomplished. Just prior to the point that each cuvette has made a complete circuit and is again being posi-tioned beneath and aliquot dispenser mechanism 36 there is a laundry stdtion 48 having probes and mechanisms for removing ~0 the reactants, if any, from the cuvette, washing the cuvett:e and making it usable for receipt of a new aliqu~t.
The data-generating means 34 are characterized by the presence of a plurality of photodetectorS radially arranged around a rotor 56 and comprising a source of radiation such as a lamp 50 and individual radiation dc~ectors 52 which can l~e pho~oelectric cells, photomultipliers or thc likc. Each de-tector 52 may have its own light source 50 as shown in the embodiments of FIGS. 2 and 3 or there may be a sing]e light source such as the lamp 50 in the embodiment of FIG. ~. (The same reference numerals are applied to the same or equivalent components in the two embodiments).
In the first embodiment the individual lamps 50 are lo-cated outboard of the path followed by the circular array of cuve-ttes, while in the second embodiment the single lamp 50 is located at the axis of the rotor 56.
In both embodiments the photodetector means are wholly carried by the rotor 56 insofar as the source and detector 52 are concerned. The radiation paths 54 in all events are at most about the radius of the rotor 56 and usually, as for example 113~

in the embodiment of Figures 2 and 3, a fraction of the rotor radius. Thus, the path is a few centimeters long and ha~ he barest minimum of optical elements in the train.
The advantages of the invention are principally derived where there is a plurality of photometers mounted on the rotor 56 but some of the advantages of the invention are available if only one photometer is utilized; hence reference to "photometer means" is intended to encompass both concepts.
It is clear that in a single photometer as compared with a rotor having eight photometers the rate at which data can be gathered would be less for the single photometer than for the multiple photometer device, assuming that the number of cuvettes in the turntable and the speed o~ rotation of thc rotor are the same in both cases. A single photometer apparatus can have its rate of data generation increased by increasing its speed of rotation. The capacity of data handling, storage and so on of the data processing means will be dependent upon the amount of data being generated. Likewise the complexity of the data processing means will be related to the variety o data generated. All of these factors and more come into play in the choice of the number of photometers, the speed of the rotor, the wavelengths at Which measurements are made, and the chemical reactions which can be handled by the apparatus.
For comparison purposes it is pointed out that the scale of the drawings in Figures 2 to 4 i5 such that the diameter of the rotor 56 measured below the location of the lamps 50 in Fi~ure 3 is approximately 30 centimeters so that the total optical path from lamp 50 to the photoresponsive device i5 -- 7_ ~ 38~2Z~IL

less than about 2 centimeters in the.embodiments o Flgures 2 and 3 and less than about 8 centimeters in the embodiment of Figure ~.
The circle of cuvettes 32 carried on the disc or turntable 74 rotates on the axis 58 which is also the axis of rotation of the rotor 56. Thus, the cuvette array and the photometers are concentric. The mounting and dri.ving means for the rotor 56 and the turntable 74 will be detailed with reference to Figures 2 to 4; however operational, timing and position relationships can be considered with reference to Figure 1.
As mentioned above, the rotor 56 in Figures 2 to 4 may be considered to have a diameter of about 30 centimeters which indicates a scale of roughly half-sixe in those Figures Figure 1 is illustrated at about one-fifth full size. In neither case is this intended to be limiting since the invention has broad application to many different forms and sizes of apparatus.
It will be apparent from the foregoing that during its complete circuit of movement for a single revolution o the ~20 turntable 74 any gi.ven cuvette 32 will have had its ali~uot subjected to fluid processing, chemical reaction and measurement, and as well will be prepared to receive a new aliquot for the repetition of the cycle. The path of the cuvettes is a circle in the apparatus which has been illustrated and will be described : '5 as such, but modified forms of the invention may vary this.
The turntable 74 will be indexed at a relatively slow rate, making a total of about five to twenty revolutions per hour, with the periods of dwell somewhat longer than the periods 1~.31~ 2~
-of movement. This speed is said to be relatively slow in contrast to the speed of the rotor 56 with its photometers ~hich will ~e normally rotatiny at a speed of as much as several hundred revolu-tions per minute. Thus, for each dwell period, at which time the measurements are prcferably programmed to be taken, there can be many rotations of the rotor taking place with the corresponding number of measurements being made by all photometers of all cuvettes. Preferably there should be a minimum of one revolution of rotor 56 per dwell period In this way, many time spaced photometric measurements of the reaction in any specific cuvette can be made, recorded and/or stored for data processing in a single circuit of the cuvette path, that is, during one revolution of the turntable 74.
The described mode of processing and endpoint determination can readily be effected in this period of time, not only for the aliquot in the single cuvette 32 but for a continuous number of aliquots being added to and removed from the cuvettes 32 of the turntable 74.
If there are 120 cuvettes 32 mounted on the turntable 74 and the turntable is indexed onoe every six seconds, one full circuit is achieved as a single revolution of the turntable 74 relative to the housing carryin~ the data generating components 34 every twelve minutes. If the rotor 56 and its eight photo-meters rotate around the axis 58 at a speed of one revolution every six seconds, this is a relatively slow speed of ten revolutions per minute or 120 revolutions of the rotor 56 for cach revolution of the turntable 74. If we assume that measure-ments are belng made at all times, each cuvette 32 of the array _ g _ 1~.3~;~21 on the turntable 74 will be scanned photometrically 960 times in a complete circuit relative to the housing carrying the dat:a generating components, for example, relative to the point where the aliquot has been inserted. If the speed of the rotor 56 is doubled the nurnber of measurements will increase to 1920 times, but it should be appreciated that since this is for only one cuvette and its aliquot, the total number of measurements made in a single revolution of the turntable 74 is of the order of 18,000 for the slower speed of the rotor 56 and 36,000 for the double speed mentioned.
Since some of the positions where cuvettes 32 will be located will be employed for laundering the cuvettes, some will be employed for injecting the aliquot and carrying the same to the reagent insertion location and some may even be employed for agitation, the total number of cuvette positions around the circular path where the measurement or monitoring is taking place may be less than the total nu~ber of cuvettes. Thus the total number of measurements men~ioned above may be less than stated by an amount which takes into account the locations needed for the above-mentioned functions. It might be mentioned that monitoring may be continued at every position, if desired, leaving the data processing control means to discard readings which have no significance. Readings made during periods where laundering is taking place could be equated to blank measurements and even some information can be acquired from the aliquot in non-reactive condition before the introduction of reagents For the purposes of the discussion which follows, it will be assumed that 800 separate photometric measurements can be made on each aliquot where the rotor is rotating at ten revolutions per _lQ

............ ~
minute, there are 120 cuvettes, the indexing is taking place at a rate of one revolution of -the turntable 74 in twelve minutes, each step of the indexing occurs every 6 seconds and ~here are several stations along the path of the cuvette array which are occupied by functions that are not concerned with photometric monitoring.
Since 800 measurement points of a reaction, each measurement being three-fourths of a second apart during ten minutes, may not be required and since certain chemical tests can be monitored better at a specific wavelength, each of the photometers can be provided with a specific filter 60 so that each photometer can produce radiation and make measurements at its own wavelength Assuming that each of the filter5 60 i9 di~ferent and in~ormation from a specific aliquot in a specific cuvette most valuably can be obtained from only one o~ the eight photometers, then there can be obtained ~rom such one photometer one hundred measure-; ments of the reaction of that one aliquot during the ten minute cycle because there is one measurement every six seconds Certainly, if it is desired that a reaction be monitored more often than once every six seconds, more than one o~ the photo-meters can be constructed to operate at the same wavelength.
It is pointed out that the photometers which are illustrated ` in the drawings are equally spaced around the rotor 56, but other arrangements where the photometers are grouped or spaced '5 unequally are encompassed by the scope o~ the invention Bichromatic determinations may be desirable in pairs of photo-meters very closely spaced.
As known, with the proper choice oE reagents, several ~L38;~2~

different reactions can be monitored at the same wavelength;
hence, with a capability of several different wavelengths and suitable reagent selection, numerous different tests can be processed by the apparatus. Since all of the cuvettes are being scanned by each of the photometers, the availability of different photometers monitoring at different wavelengths permits aliquot alone as well as a reaction in a cuvette to be monitored by more than one photometer and therefore at more than one wavelength, with the separation of time between monitoring at different wavelengths being three-fourths of a second in the illustrated embodiment. It will of course vary pursuant to construction and requirements. Each aliquot need not be monitored at all wavelengths, nor does each sample have to provide aliquots for all tests capable of being achieved by ]5 use of the apparatus. The data into the input means 18 and the master control unit 20 can be controlled and programmed in such a manner as to command the execution of only those tests requested for each sample and will employ cuvettes only as needed, thereby reducing the total amount required of sample and re~gent volumes and maximize ~he utilization of the cuvette positions and the photometer means to maximize sample through-put of the apparatus.
The apparatus does not require a fixed set of several tests for each sample even if different ones of the set of tests would '5 not be requested for certain of the samples nor, as is also well known in the prior art, does the apparatus cause empty cuvettes representin~ "skipped" tests to occup~ space in the rotatin~ array on the turntable 7~. The jus-t men-tioned ana other 1~.3~;2Z~

sample processing control functions by the master control unit are carried on a function control bus 62, shown in Figure 5, It will be mentioned at this point by way o~ recapitulation ancl emphasis that the apparatus of the invention has great flexibility in being applicable to many choices of testing but without sacrificing economy or throughput. As mentioned above, each aliquot need not be monitored on all wave lengths, In addition to this, each sample does not have to provide aliquots for all tests capable o~ being accomplished by the apparatus, Test selection is here achieved without loss of analytical capacity, without wasting any of the aliquots or reagents, without carrying out any unnecessary tests whose data are u~eless and without skipping any cuvettes. On this account it can be appreciated that the throughput o~ the apparatus is also not af~ected by the great versatility of the device, It may be said of this apparatus that it has true test selectivity without the equivocation of prior automatic chemistry devices in that if a test is not performed in a given cuvette that same cuvette is available for another test, Next, with re~erence to Figures 2 and 3, the details of one embodiment of the data generating component assembly 34 will be discussed, with some reference also to Figure 4. As shown, each radiation source 50 and its associated detector 52 are relatively close together and on a line and securely mounted to the rotor 56 and thereby define therebetween the short radiation path 54 of ~ixed length which lies on a radius ~rom the axis 58, The rotor 56 is arranged to rotate on the axis 58 and is provided with a depending rotary sleeve 64 which is journaled on bearing5 66 mounted to the housing base members 68 and 70. Suitable 13_ 1~38;~2~

drive means 72 can be coupled to the sleeve 64 to apply the rotational movement to the rotor 56 and its photometers, two of which are illustrated in Figure 3. The photometer components ancl the short radiation paths 54 therebetween are thus held in fixed orientation with respect to each other and their radial orientation with respect to the axis 58. The journalled mounting of the rotor 56 provides a precision orientation of the radiation path 54 with respect to its distance from the axis 58, such distance remaining substantially constant as the rotor 56 is rotated.
The bearings 66 can be of any suitable conventional design and construction. The criteria for such bearings are accuracy, smoothness, reliability, in addition to providing the thrust support needed in view o~ the weight of the rotor 56 and its components. Radial support requirements in view of the weight and forces generated during rotation of the rotor 56 must also be taken into consideration in choosing the bearings 66.
The construction described together with a judicious choice of high quality bearings 66 will result in accurate tracking of the photometers during rotation of the rotor 56 thereby enabling accurate and repetitively identical photometric measurements to be taken during operation of the apparatus. Notwithstanding precautions taken to assure accurate tracking and elimination of any eccentricity during rotation, the nature of the invention is such that some eccentricity during this rotation will not adversely a~fect accuracy.
The annular array of cuvettes 32 is mounted on the turntable 74 as explained. These may be removable cuvettes or the turn-11.38223L
table may be molded or otherwise formed with the cuvettes 32 permanently attached thereto. The turntable 74 is journalled ~or rotation on the same axis 58 as that oE the rotor 56 and the disposition of the turntable is above the rotor 56 so that access may be had to the entrances to the cuvettes 32 from above, as will be explained. The array of cuvettes extend downwardly from the body of the turntable 74 which is somewhat disc-like or planar in character, defining an annular ring path through which all of the cuvettes travel during rotation of the turntable 74. This ring intersects all of the radiation paths 54 of the photometers mounted on the rotor 56. These paths 54 are radially arranged about the rotor 56 and in the case of the very short paths 54 of the embodiments of Figures 2 and 3 the spaces between the filters 60 and the lamps 50 also define a similar L5 ring that coincides with that formed by the path of cuvettes 32.
The photometers 50-52 can be mounted on the upper surface of the rotor 56 in any suitable manner by clamps or brackets or the like or could be mounted on the interior of a thickened disc forming the rotor which could be accurately molded to ~0 receive the same. In such case, a groove or trough or annular configuration could be formed in the upper surface of the rotor 56 in annular coniguration to receive and clear the depending array of cuvettes during their rotation. The radiation paths could then be arranged to pass through the groove in a radial ?5 direction which will enable them to pass unobstructed through the walls of the cuvette where the aliquot heing measured is located. The cuvettes are obviously made out of some transparent or translucent material and should have properly oriented walls _15_ 13..38;~Z~

that do not refract or scatter the beam o~ radiation passing through the same.
The cuvette turntable 74 has a hub with depending collar 76, is centered on the axis 58 and is journalled ~or rotation by means of bearings 78 that are mounted between the collar 76 and the sleeve 64, thus permitting the cuvette turntable to be rotated independently of the rotation of the photometer rotor 56. Rotation of the turntable 74 in an indexing mode can be effected by conventional means not shown in Figure 3, but illustrated in Figure 4 and discussed with respect thereto, Since the turntable 74 and the photometer rotor 56 are coaxial on the same axis 58, and the collar 76 of the turntable 74 rotates within the sleeve 64 of the rotor 56, the path of the cuvettes and the area swept by the photometers are concentric and the cuvettes are caused to intercept the short radiation path 54 of each photometer with highly reproducible positional accuracy thereby promo~ing accurate photometric measurements without need for complex light guiding arrangements employed in the prior art.
2C To enhance the continuously smooth rotary motion of the photometer rotor 56 it can be designed with weighted circumfer-ential volume to operate with a flywheel effect. In contrast the cuvette turntable 74 should be relatively lightweight if the indexing thereof is to be accomplished in steps with dwell periods between steps.
Figure 4 illustrates primarily a sli~htly modi~ied arrange--ment of the photometer means 50-52. Such modification and other differences between Figures 3 and 4 will be presented after the discussion of Figure 5, which includes explana-tion of most of -l6-1~.3~

the operation of the structure shown in both Figures 3 and 4.
As shown in Figures 3-5, the electrical output rom the radiation detectors 52 is coupled to electrical components for a~nalog to digital conversion and transmission rom the data generating component assembly 34 to the control console 10 (Figure 1). Preferably, the electrical components would be secured to portions of the rotor 56 and its sleeve 6~, by way of circuit components, circuit boards and connectors such as 80 and 82, so that the electrical components can move along with their associated photometers, during their rotation around the axis 58, without the need for slip rings, cammutators or the like at the sensitive points of the circuit or more complex wiring arrangements. The transmission oE a l~rge quantity of discrete electrical measurements in the form of analog values from a plurality of radiation detector5 52 that is continuously moving presents problems, both mechanical and electrical.
It is believed that the need or greater throughput of precise data from many photometers, concerning numProus chemical tests being carried out on a high number of aliquots, is not practically satisfied by the prior technology. The arrangement in Figure 5 provides an efficient, flexible, yet simple and precise mode of data transmission.
Commencing with the top left of Figure 5, there is shown one of the assemblies mounted on the rotor 56 which will be termed a photometer module 84 with its radiation source 50 directing its radiation to pass through the walls o one of the cuvettes 32 and strike the sensitive surface of the detector 52, after passing through the filter 60. The detector could be a 13..38%Zl J

silicon diode, a photomultiplier, vacuum photodiode or other photoresponsive device. A few milliseconds of scanning time by one of the photometers moving past an effectively stationary cuvette will be sufficient to obtain the required analog measurement of the radiation incident on the detector 52 to enable eventual calculation of absorption and absorbance. The detector 52 responds to the amount of radiation ~ransmitted through the aliquot in the cuvette and the cuvette walls by generating an electric signal proportional to such amount of radiation. An integrator 86 is connected to the detector and converts the generated signal to an output voltage signal which is proportional to the transmittance of the aliquot. A
logarithmic analog to digital converte~ 88 is coupled to the output of the integrator and generates as its output on a line lS 90 a digital signal which is a function of the absorbance of the aliquot. For ease of illustration, only one of the eight photometer modules 84 is illustrated, but all eight of the photometer output lines 90 are shown.
Since at one instantaneous position of the continuously 'O moving photometer rotor 56 all eight of the detectors 52 could be respectively receiving radiation which has traversed the samples in eight different cuvettes, a digital multiplexer 92 is connected to all of the photometer output lines 90. The multiplexer operates in typical switching manner under the controlof ~5 a control unit 94, by way of a control line 96, discretely to transfer the data from each of the log A/D converters 88 to the data control unit on a data line 98. Such data can be handled in the form of binary bits, with one binary word representing _18_ 1~L3~

the absorbance reading from one cuvette. The correlation of each specific absorbance data word with its aliquot or cuvette iden~ification can be accomplished by the data control unit.
The means for such identific2tion and coupling same to data S control unit are not illustrated. After the data word has been transferred to the data control uni~ 94, that unit will generate a reset command on a line 100 to the appropriate log A/D converter 88 to enable that converter to receive the next analog signal derived from the next cuvette to be scanned by that one photometer 84.
Each integrator 86 will be reset by its A/D converter when its digital word is fed into the rnultiplexer. A reset line 102 carries that command, usuall~ prior to the resetting of the A/D converter by the data control unit 94. To ensure that the radiation through one cuvette does not include radiation ~rom an adjacent cuvette as seen by its integrator 86 the integrator can be enabled by a start integrate command line 104 which can be triggered in response to one of various conditions, such as: a timing relationship with the rotor ~o drive means 72, or a positioniny of the cuvette relative to the radiation path 54, or the shape of the output signal waveform from the detector 52.
Depending upon the sophistication of the data control unit 94 and the size o~ its memory, if any, the manner of data input-output handling can be variable. For example, by employing a simple data control unit, each instance that a digital word is fed into the data control unit it can be transmitted to the master control unit 20 and be processed therein for receipt by t.l-e readout unit 22. The mastér control unit can have a data --19_ 1~3~3~%~

storage and correlation capacity as well as the earlier mentioned function control, instruction and command information.
On the other hand, if the data control unit has sufficient storage capacity, at least all data words such as the 960 mentioned which are obtained during one or nore rotations of the rotor 56 can be stored therein.
Assuming that each of the photometers 52 is operating at a different wavelength and that a specific cuvette 32 is to be monitored by only the one photometer 52 operating at that wavelength which optimizes the measurement of the specific reaction occurring in that cuvette, then of the 960 data words received by the multiplexer 92 during one cycle or revolution of the photometer rotor 56, only one hundred twenty of those words (for the example described) normally would be needed by L5 the master control unit 20 The determination of which data words are to be employed for data processing is developed from the input information which associates specific samples with specific tests. The master control unit 20 then assigns each specific cuvette to a sample and a test and thereby a specific photometer; whereupon, the data word required rom that cuvette for each revolution of the rotor 56 can be identified and related to the data words from the same cuvette 32 obtained from each of the next following rotor revolutions, which in the preferred embodiment totals one hundred twenty revolutions of the photometer rotor 56.
Depending upon the desirable extent of communications between the data control unit 94 and the master control unit 20, the sizes of their memories, the speed of operation of the -20_ 1~ 38~Zl apparatus, etc , all of which involve cost, throughput and other factors which influence engineering design, the engineering design can cause all ninety six thousand words to be transmitted to the master cont~ol un;t for its selection of the needed twelve thousand data words; or, the two control units 20 and 94 can communicate such that only the desired twelve thousand words are transmitted from the data control unit to the master control unit.
The engineering design is influenced by the timing of the transmission of the data words from the data control unit to the master control unitO There may be a finite amount of unused time between the scanning of each cuvette, while the rotor 56 is moving into alignment with the next set of eight cuvettes, and also at the end o each revolution, when the cuvette array is indexed one step. Since the apparatus can operate in the continuous mode, as earlier described, one revolution can be followed by the next without any significant disruption, as contrasted to the batch mode of operation Hence, data also can be transmitted in a continuous mode and not stored until some later time and then dumped into a processing unit. This continuous transmission of data from the data generating component assembly 34 to the control console 10 may be with some control by the data control unit 94, rather than exclusively by the master control unit 20, as above-~5 mentioned.
In reerring to unused time above, that is, time between the scanning of cuvettes or at the end oE a revolution, no limitations on the invention are int~nded. Thus, it is feasible _21~


to measure dark current between cuvette scannings to set the photometer scales. The readings can readily be identified by the control unit and processed as desired and proyrammed.
Although a continuous operation mode has we]l known advantages over batch operation, there can be conditions which warrant batch handling. The apparatus of this invention can be used in batch processing. For example, the entire cuvette turntable 74 could be in the form o~ a removable disc to be replaced by one or more similar discs having the cuvettes already filled with aliquots and possibly even reagents, each replacement disc being a batch. If the batch would consist of only a few ali~uots, the cuvette disc could be constructed in segments and then only a segment or portion of the disc be replaced with a prepared segment of cuvettes. Likewise, a stat or urgently needed test could be "inserted" into the apparatus.
Such a structure would have a turntable like that shown at 74 with a thin plastic disc, perhaps formed by vacuum molding a synthetic'resin sheet with the depressions forming the cuvett~s, capable o being clamped or snapped onto the upper surface of the turntable. The operation of the apparatus would ; not be too much different, being required only to enable proper orientation of the replaceable disc to provide sample identification and with some modification which starts and stops the apparatus so that the attendant may remove the used disc and replàce it with a new one.
In normal operation such a clisc or turntable would not be required to rotate and its cuve-ttes would be scanned by the _22_ 1~ 3~

plurality of photometers during rotation of the rotor 56, Stepping of the disc or turntable 74 would be useful where the ~apparatus could be alternated be~ween continuous and batch modes, The removabilit~ of the disc Gn ~he turntable 74 could be of advantage where stat testing is to be done and it is not desired to integrate such tests in with the routine ones being processed. Stepping could also be of advantage along with removability in a batch mode where the stepg carry different sets o filters into the radiation paths.
In a batch method device where the rotor carries a plurality of photometers, such photometers could employ individual lamps 50 for each photodetector 6Z or a single central source of radiation serving all photometers.
One variation of the invention could comprise a fixed or indexing turntable with cuvettes and a rotor having a single photometer, the rotor also carries a filter wheel arranged vertically and intercepting the beam of radiation from the photometer before it passes through the cuvettes, The rotor in such case is arranged to stop momentarily at each cuvette ~o and automatically rotate the filter wheel to provide several measurements at different wavelengthsthat are identified by suitable synchronizing means to be sent to the proper address of the storage or recording device through data control means, In this way, the effect of plural photometers is achieved '5 without the need for any duplication of photometers.
It is pointed out that the reference to the rotation or revolutions of the rotor 56 is not to be considered limited to movement in one direction since it is feasible for the rotor ~.382Z~
56 to oscillate by rotating substantially one revolution and then reversing itself to rotate a ~evolution in the opposite direction, etc.
Next, with reerence to Figure 5, there will be disclosed both types of data flow and control; first, that which requires two-way communications between the control units 20 and 94;
and second, one-way communications The latter, although simpler than the former, would require more sophistication and also more storage capacity by the master control unit.
Two-way communications between the master control unit and the data control unit can be accomplished with the aid of a pair of communications logic units 106 and 108, a pair of transmitters 110 and 112, and a pair of receivers 11~ and 116.
The elements 106, 110 and 114 would be housed in the rotating portion of the data generating component assembly 34. The corresponding elements 108, 112 and 116 would be located in the control console 10 and/or a stationary portion of the assembly 34. A control bus 118 and a data bus 120 link the data control unit 94 with its communications logic unit 106.
In like manner, control and data buses 122 and 124 link the master control unit 20 with the communications logic unit 108. Typical of the bidirectional control information on the buses 118 and 122 would be the availability of one or more data words to be written into or read from one or the other or both of the memories in the units 20 and 94 and the availability of the ~ssociated logic unit 106 and 108 to receive or transmit such data.
Since in the now being described embodiment o~ the

-2~_ 1~3~2Z~L

electronics there is to be two-way communications between the data con-trol unit in -the reaction table and the master control unit in the control console, the control and data buses 118-124 will be bidirectional as indicated by the arrowheads in Figure 5. Also, the communications logic units 106 and 108 will possess two-way capabilities.
The bidirectional data buses 120 and 124 will carry each data word serially in parallel bit order, but the inputs from the receivers 114 and 116 and the outputs to the transmitters 110 and 112 will be serially by bit. The preferred emhodiments of the transmitters and receivers, as illustrated in Figures 3 and 5, respectively are photoemissive and photosensitive, Figure 4 employs a slip ring a99emb1y 110-1]6; however, olther forms of transmission and reception are possible, such as of the radio frequency type, and are encompassed within the general terms and are not to be considered limited by the illustration of the preferred embodiments.
Phototransmission, as by a photodiode, is both simple and well suited to the handling of binary serial bit data and is well known to those skilled in the art. Moreover, photo-emission and reception are less subject to interference than radio transmission, especially when the elements 110-116 can be closely spaced.
As shown in Figure 3, the transmitter 110 and receiver 114 can be housed within the sleeve 64 and rotate therewith close to the axis 58. The associated elements 116 and 112 could be stationary and lie close to the projection of the axis 58 and be wired into the logic unit 108 in the control console 10.


Mounted in such a manner close to axis 58, the fact that the transmitter 110 and receiver 114 ~re rotating will not cause errors ln the binar~ bit data transmission. On the other hand, if the magnitude oE a signal, rather than presence or absence thereof, were the measure of the test clata and the control commands, then relative movement of the transmitters and receivers could produce transmission errors.
From the foregoing it will be appreciated that for economical use of storage capacity in the master control unit 20 only the desired data words should be transmitted ~rom the data contro] unit 94. To effect such economy the input information from the data input means 18 will enable the master control unit to establish a listing of the aliquots or their cuvette-~ rom wh~ch data is desired. As new samples are added to the sampie disc 30, associated input information fed into the master control unit and old samples complete their testing the "desired" listing will be updated continuously.
As each data word is received by the data control unit 94 from the multiplexer 92 it will, by two-way communications, be checked with the desired data list and only be transmitted to the master control unit after an affirmative comparison. This communication will require the data control unit and its logic unit to have interchanges on the buses 118 and 120 regarding:
the act that a data word has been received from the multiplexer, identification of that word and that the logic units 106 and 108 are ready to communicate that identification information ` to the master control unit.
; In like manner, the master control unit and its ~uses ~13~;~2~

122 and 124 with its logic unit 108 will: acknowledge availability to communicate, receive the identi~ication data, provide a comparison reply and then either cause the data word to be discarded by the data control unit or cause it to be transmitted for storage by the master control unit.
Each communication will re~uire transmission and receipt by one or the other pair of components 110 and 116, or 112 and 114.
In the other embodied form of data communications~ all data words are transmitted from the data control unit 94 to the master control unit 20 and the latter then itself will decide which data words to continue to store for ultimate readout purposes. Because of this simpler form of communications the data buses 120 and 124 need only feed in the direction toward the master control unit, the communications logic unit 106 will operate only as a sending unit, the communications logic unit 108 will operate only as a receiving unit and the transmitter-receiver pair of elements 112 and 114 will not be required. The bidirectional control buses 118 and 122 between ; 20 the control units and their respective communications logic ; units are required for the purposes above-mentioned.
The differences between the embodiments of Figures 3 and 4 will now be described. First, concerning the photometer means, the radiation source 50 of Figure 4 i5 located at the axis 58 and comprises a single element tungsten lamp rather than a plurality of lamps p~sitioned around the periphery of the photometer rotor 56 as in Figure 3. The source 50 in Figure 4 is connected to the rotor 56 for rotation therewith.
_27_ ~1.3~2Z~

A plurality of lens-containing optical tubes 126 are mounted to -the photometer rotor 56 of Fi~ure 4 such that one end of each tube is proximate to the radiation source 50 and the other end of each tube is close to the annular path or pattern traversed by the cuvettes and is aligned with a specific one of the radiation or photometric detectors 52. The photo-metric detectors 52 are also mounted on the rotor 56 substantially as in the Figure 3 e~bodiment. The paths or patterns swept by the beams of radiation r~eaching each detector is in effect the same as in Figure 3.
one advantage of employing a single source 50 is that it is easier to dissipate the heat generat~d thereby and thus easier to regulate the temperature o~ the cuvettes 32. Note that in the embodiment shown in Figure 3 the individual lamps are located quite close to the annular ring defined by the cuvette path so that the heat of these lamps could be radiated or transmitted to the materials carried by the cuvettes The nature of many of the reactions whose characteristics are being measured is such that temperature changes are critical.
As a matter of fact, means will often be provided for incubation of the cuvettes during their scanning and the arrangement of Figure 4 enables such structure to be easier achieved and more effective in operation because of the absence of heat sources Another advantage of a 9ingle source such as in Figure 4 is that there is no problem with different intensities, colors ; or wavelengths which can be expected in a plurality of differentlamps, even where matched. What~ver happens to the single source lamp 50 happens to all readin~s made so that the effect is not felt where relative measurements are made. The lamp 50 can be _Z8-~ 3~2;~

cooled very easily by air circulated in its vicinity in a manner which will not cool, for example, the cuvettes. The power supply for a single source 50 is simpler and more economical.
In the views described thus far shown there is a single beam 54 which passes through the cuvette 32 and thence impinges upon the photodetector 52 after passing through a filter 60 which is usually in close proximity if not incorporated into the photodetector. In the structure of Figure 4 it is feasible to focus the light beam into a very fine pencil for passage through the lower portion of the cuvettes 32 but in addition it is feasible to incorporate beam splitting means into the focussing tube or outside thereof to provide two beams which may be directed in parallel paths through different levels of the cuvettes for investigating different strata of the analyte.
Such a structure is shown in Figure 4a to be described in detail below.
In Figure 4a components equivalent to those of Figure 4 carry the same reference numerals primed. The rotor 56' has a focussing tube 126' which directs a beam 54' derived from a source such as 50 (not shown in Figure 4a) to a semisilvered or dichroic mirror 150 arranged at 45 in front of the tube 126'. A part of the beam passes through the mirror 150 and becomes a bottom beam 54'b and another is reflected at 90 upward and thence reflected from the 45 angled mirror 152 to become the upper beam 54'u. These beams pass through dif~erent levels of the liquid 154 carried in the cuvette 32' mounted in the turntable 74' which is dispo~sed to move in a path which _29_ 1~.382:~

carries it and its companion cuvettes through the yroove 156 provided in the rotor 56.
There are two photodetectors at 52' and 52" mounted on ~e rotor 56 in suitable cavities aligned ~ith the mirrors 150 and 152, respectively, and thus aligned to receive the beams 54'b and 54'u against their sensitive surfaces. Each is provided with a filter 60' and 60", respectively. Openings 158 and 160 respectively enable the beams to pass.
It will be obvious that the beam 54' emerging from the focussing tube 126' splits, part going through a lower stratum of the liquid 154 and part going through an upper stratum of the same liquid. The photodetectors 52' and 52" are independent, each providing a different signal which can be transmitted through suitable connections to data processing equipment to provide additional information concerning the reaction which may be going on in the cuvette 32'.
Figure 4 shows the drive means for the cuvette turntable 74, which was not illustrated in Figure 3, because of drawing space limitations. A motor 128 has its drive sha~t 130 coupled by a pinion gear 132 to a suitably mating configuration 134 on the periphery of the turntable 74. I~ the indexing of the cuvettes is to be in steps, the motor 128 could be a stepping motor, or there could be provided linkage, clutch means, etc., for providing appropriately timed stepping from a ~5 continuously driven motor.
As earlier mentioned briefly, a slip ring assembly 110-116 can provide the receiver and transmitter needs of the apparatus and couple data and other communications from and to the 1~.3~ZZ~

reaction table 34 and the master control unit 20.
From the above, it now should be understood how the en~ire apparatus operates with its moving photometer means and preferably in a continuous mode to place into the master control unit 20 the digitized values of the readings related to absorbance from the data generating componen~s assembly 34.
Since reaction can be monitored at frequent intervals during a prolonged period o~ time rather than a small portion thereof, both rate and end point data are obtainable Once into the master control unit, the raw data can be associated with each test and supplied to the readout unit 22 without any data reduction, conversion or analysis, such being left to the skill of a technician in interpreting the 5ame. In a preferred mode of operation the master control unit would have the capability of associating the data for each test, obtaining mathematic rate and/or end point determination, then converting that information into a reading o~ the chemistry value in the desired concentration units for the test, thereafter feeding the results into the readout unit.
2~ Although some variations in structure and operation of this chemical reaction monitoring apparatus have been disclosed hereinabove, other variations are capable of being made. For example, the preferred embodiments teach continuous movement o~ the photometer rotor; however, a stepping device movement can be employed. Also, the photometer means are spaced around the circum~erence of their support, since such positioning enables a uni~orm weight distribution around the support; however, the photometer means could be mounted witn variable spacing especially _31_ 1~;.3fl~

if the path of motion is other than circular. It may be desired to employ disposable cuvettes. If so, the laundry station 48 would be replaced by means for removing used cuvettes and for inserting clean cuvettes into the cuvette turntable 74. At least in such situation, the cuvettes need not move around a closed path. Reagents need not be liquid but may dispensed dry. Cuvettes may be used in a disposable mode with the reagent already in place, requiring only the addition of the aliquot and a diluent.

Claims (5)

1. Apparatus for monitoring chemical reactions occur-ring in a plurality of liquid or the like sample substances carried by a plurality of respective sample support members and which produce an optical effect when exposed to radiant energy which comprises:
A. a support structure, B. a sample support member carrier disposed in a first plane and having a plurality of sample support mem-bers disposed thereon in a circular array around the periphery of the carrier and the array having a central axis normal to said plane, the sample support member carrier being mounted on the support structure, C. a rotor disposed parallel with the sample support member carrier and mounted for rotation on the said axis, D. a photometer arranged on said rotor and including a photoresponsive element and there being radiant energy source means serving said photoresponsive element and directing a beam of radiant energy there-to, said beam having a fixed orientation relative to said photo responsive element that is maintained at all times during rotation of the rotor, the source means and element being arranged on a radius of said rotor and located in such a manner that the beam will be intercepted by the sample support mem-bers in sequence during rotation of the rotor, E. a filter change device having a plurality of filters mounted on the rotor in a second plane normal to said first plane between said source means and photoresponsive element and located in such a man-ner as to have the said beam pass through one of said filters before reaching any of said sample support members, said apparatus including means for operating said filter change device to dispose selective ones of said filters in the beam, F. means for driving the rotor in a rotary movement, G. the photoresponsive element being responsive to the beam to produce electrical signals when inter-cepted by sample support members, the signals be-ing related to the chemical condition of sample substance, if any, carried by the respective sample support members.
H. means for generating usable data from any such sig-nals associated with support structure and carrier and I. means for coupling the signals from the rotor to said last-mentioned means.
2. The apparatus as claimed in claim 1 in which the carrier is non-rotatable.
3. The apparatus as claimed in claim 1 in which the carrier is rotatable and means are provided to rotate said car-rier in a step-wise movement at a rate slower than the rotation of said rotor.
4. The apparatus as claimed in claim 1 in which the carrier is wholly removable from the support structure to en-able replacement thereof by another such carrier having dif-ferent sample support members.
5. The apparatus as claimed in any of claims 2, 3 or 4 in which the filter change device is a wheel, the rotor is arranged to stop when the beam is aligned with a sample support member and means are provided to rotate the wheel to subject said beam to respective plural filters of said wheel.
CA 391039 1977-06-20 1981-11-26 Apparatus for monitoring chemical reactions and employing moving photometer means Expired CA1138221A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US80816677 true 1977-06-20 1977-06-20
US808,166 1977-06-20
US846,337 1977-10-28
US05846337 US4234538A (en) 1977-10-28 1977-10-28 Apparatus for monitoring chemical reactions and employing moving photometer means
CA 305783 CA1116430A (en) 1977-06-20 1978-06-19 Apparatus for monitoring chemical reactions and employing moving photometer means
CA 391039 CA1138221A (en) 1977-06-20 1981-11-26 Apparatus for monitoring chemical reactions and employing moving photometer means

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013026959A1 (en) * 2011-08-24 2013-02-28 Labrox Oy Microtiter plate reader apparatus and dynamic filter storage

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013026959A1 (en) * 2011-08-24 2013-02-28 Labrox Oy Microtiter plate reader apparatus and dynamic filter storage
US9354173B2 (en) 2011-08-24 2016-05-31 Labrox Oy Microtiter plate reader apparatus and dynamic filter storage

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