CA1138220A - Apparatus for monitoring chemical reactions and employing moving photometer means - Google Patents

Abstract

ABSTRACT
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.

Description

~ 1~L382;20 -This invention relates to apparatus for monitoring repeatedly the absorption of electromagnetic radiation by a plurality of 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 of 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 efected 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 de9cribed 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 reguire 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 measurement 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 t , 25 and manipulation by the laboratory technician. The nature of the process cannot help but re5ult in relatively low throughput.

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Thc disadvantages of the previous proposals may be over-come by progressively measuring absorbance changes in sample alicluots in a plurality of cuvettes arranged in a circular ar-ray which is rotatcd in a slow or step-by-step motion. As the cuvcttes are advanced sample al:ic~uots are introduced int:o each cuvette in a first position, cach 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 gellerate an electri.cal 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 before making a completc circuit and each ~ignal is convert~d from an analog to a di~ital si~7nal before it is trans-mitted from the rotating photometers to a stationary control receiver or computer. Prior to arriving at the fi,rst position after a complete circuit the tested ali.~uot .is removed rom 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 cuvettc

- 2 ~382ZO

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 fragmentary 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;

~38;~0 Figure 4a is a fragmentary view of a portion of Figure 4 but illustrating a modified form of the invention utilizing a split beam arranyernent; 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 hereina~ter, 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 inormation to a readout unit 22, which can include a visual display 24 and 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 o~ 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

3~3220 28 in a sample disc 30. Thereupon, the master control unit 20 can control the transferring of sample aliquots into cuvettes 32 mounted in an annular array in a turntable which is part of the data generating portlon 34. An ali~uo-t and diluent transfer mechanism 36, forms 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 swing free thereo~ in an .....

3~;ZZ~) arcuate path.
Between the time and position that the aliquot is dis-pensed and the first reagent is dispensed there i5 a distance alony the path of the cllvettes duriny which measurement of the transmittance of the aliquot with its diluent and the 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 the reactants, if any, from the cuvette, washing the cuvette and making it usable for receipt of a new aliquot.
The data-generating means 34 are characterized by tl-e presence of a plurality of photodete(tors radially arranged around a rotor 56 and comprising a source of radiation such as a lamp 50 and individual radiation detectors 52 which can be photoelectric cells, photomultipliers or the like. Eacl- 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 single li.ght source such as the lamp 50 in the embodiment of FIG. 4. (T}le 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 cuvettes, while in the second embodiment the single lamp S0 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 5~ in all events are at most about the radius of the rotor 56 and usually, as for example ~131~2Z~
-in the embodiment of Figures 2 and 3, a fraction of the rotor radius, Thus, the path is a few centimeters long and has the 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 inv~ntion 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 sin~le 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 the 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 of data generated. All of these factors and more come into play in the choice of the number of photometers, the speed o~ 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 '5 scale of the drawings in Fi~ures 2 to ~ is such that the diameter of the rotor 56 measured below the locàtion of the lamps 50 in Figure 3 is approximately 30 centimeters so that the total optical path from lamp 50 to the photoresponsive device is 1131~22~) -less than about 2 centimeters in the embodiments of Figures 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 driving 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 Pi~ures 2 to 4 may be considered to have a diameter of about 30 centimeters which indicates a scale o roughly half-9ize 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 of the turntable 74 any given cuvette 32 will have had its aliquot 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 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 t~7enty revolutions per hour, with the periods of dwell somewhat longer than the perlods ~138ZZ~) of movement. This speed is said to be relatively slow in contrast to the speed of the rotor 56 with i-ts photometers which will be normally rotating at a speed of as much as several hundred revolutions per minute. Thus, for each dwell period, at which time the measurements are preferably programmed to be taken, there can be many rotations oE 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 i8~ during one revolution of the turntable 74.
The described mode of processing and endpoint aetermination can lS readily be effected in this period of time, not only for the aliquot in the single cuvette 32 but or 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 once every six seconds, one full circult is achieved as a single revolution of the turntable 74 relative to the housing carrying 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 `~5 every six seconds, this is a relatively slow speed of ten revolutions per minute or 120 revolutions of the rotor 56 for ; each revolution of the turntable 74. If we assume that measure-ments are being made at all times, each cuvette 32 of the array _ 9 _ ~3~ZZ{~
-on the turntable 74 will be scanned photometrically 960 times in a complete circuit relative to the housing carrying the data generating components, for example, relative to the point where the aliquot has been inserted. If the speed o~ the rotor 56 is doubled the number of measurements will increase to 1920 times, but it should be appreciated that since this is ~or 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 o the rotor 56 and 36,000 for the double speed mentioned.
Since some of the positions whare 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 number of cuvettes. Thus the total number o measurements mentioned above may be less than stated by an amount which takes into account the locations needea 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 launderîng is taXing place could be equated to blank measurements ~5 and even some information can be acquired from the aliquot in non-reactive condition beore the introduction o~ reagents For the purposes o 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 _ 1~

~38;;~20 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 o~ the indexiny occurs every 6 seconds and there 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 maXe measurements at its own wavelength.
~ssuming that each o~ the ~ilter5 60 is dif~erent and information from a specific aliquot in a specific cuvette most valuably can be obtained from only one of the eight photometers, then there can be obtained ~rom such one photometer one hundred measure-ments of the reaction of that one ali~uot 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 of 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 of reagents, several 1138.'ZZ() different reactions can be monitored at the same wavelength, hence, with a capability of several different wavelengths and suitable reayent 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 ali~uots 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, ther~by reducing the total amount required of sample and reagent volumes and maximize the 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 not be requested for certain of the samples nor, as is also well known in the prior art, does the apparatus cause empty cuvettes representing "skipped" tests to occupy space in the rotating array on the turntable 7~. The ~ust mentioned and other ~13Z~22~

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 of recapitulation and emphasis that the apparatus of the invention has great flexibility in being applicable to man~ choices of testing but without sacrificing economy or throughput. As mentioned a~ove, 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 of being accomplished by the apparatus Test selection is here achieved without loss of analytical capacity, without wasting any of the ali~uots or reagents, without carrying out any unnecessary tests whose data are u~eleqs and without skipping any cuvettes. On this account it can be appreciated that the throughput of 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 ~ext, with re~erence to Figures 2 and 3, the details o one embodiment o~ 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 ~5 the rotor 56 and thereby define therebetween the short radiation path 54 of fixed length which lies on a radius from 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 bearings 66 mounted to the housing base members 68 and 70. Suitable 13_ 1~3822~
-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 ana the s'nort 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 of the weight of the rotor 56 and its components. Radial support re~uirements in view of the weight and ~orces 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 trac~ing and elimination of any eccentricity during rotation, the nature of the invention is such that some eccentricity during this rotation will not adversely afect accuracy.
The annular array o cuvettes 32 is mounted on the turntable 74 as explained. These may be removable cuvettes or the turn-1~3E~'~20 q.~
table may be molded or otherwise formed with the cuvettes 32 permanently attached thereto. The turntable 74 is journalled for rotation on the same axis 58 as that of 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 cuve-ttes 32 from above, as will be explained. The array of cuvettes extend downwardly ~rom 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 slmilar ring that coincides with tha~ 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 bracXets 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 surace of the rotor 56 in annular configuration to receive and clear the depending array of cuvettes during their rotation. The radiation pa-ths 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 being measured is located. The cuvettes are obviously made out of some transparent or translucent material and should have properly oriented ~alls _15_ ~. .

113BZZ(~

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 for 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 o the rotor 56, the path of the cuvettes and the area sWept by the photometers are concentric and the cuvettes are caused to intercep-t the short radiation path 54 of each photometer with highly reproducible positional accuracy thereby promoting 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 slightly modified 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 explanation of most of 1138~20 the operation of the structure shown in both Figures 3 and ~.
As shown in Figures 3-5, the electrical output from the radiation detectors 52 is coupled to electrical components for analog to digital conversion and transmission from 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 64, 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, commutators or the like at the sensitive points of the circuit or more complex wiring arrangements. The transmission of a l~rge quantity of discrete electrical measurements in the form of analog values from a plurality of radiation detectors 52 that is continuously moving presents problems, both mechanical and electrical.
It is believed that the need for greater throughput of precise data from many photometers, concerning numerous chemical tests being carried out on a high number of aliquots, is not ~0 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 of 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 3%20 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 transmitted 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 ali~uot. A
logarithmic analog to digital converter 88 is coupled to the output of the inteyrator and generates as its output on a line 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 o 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_ ~38;~ZO

the absorbance reading from one cuvette. The correlation of each specific absorbance data word with its aliquot or cuvette identification can be accomplished by the data control unit.
The means for such identification and coupling same to data control unit are not illustrated. After the data word has been transferred to the data control unit 94, that unit will generate a reset command on a line lO0 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 multiplexer. 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 from 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 of its memory, if any, the manner of data input-'5 output handling can be variable. For example, by employing a simple data control unit, each instance that a digital word is ~ed into the data control unit it can be transmitted to the master control unit 20 and be processed therein for receipt by the readout unit 22. The master control unit can have a data --lg--1138~2~

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 storaye capacity, at least all data words such as the 960 mentioned which are obtained during one or more rotations of the rotor 56 can bé 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 oE tho~e words (for the example described) normally would be needed by 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 require~ from 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 '5 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 oE the _20-1~38~Z~) apparatus, etc., all of which involve cost, throughput and o~her factors which influence engineering design, the erlgineering design can cause all ninety six thousand words to ~e transmitted to the master con~rol uni~ 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 unit. 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 of 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 oparation.
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 9~, rather than exclusively by the master control unit 20, as above-'S mentioned.
In referring to unused time above, that is, time between the scanning of cuvettes or at the end of a revolution, no limitations on the invention are intended. Thus, it is feasible _21-. . , 1~.3fl~Z~:) to measure dark current between cuvette scannings t~ set the photome~er scales. The readings can readily be identified by the conkrol unit and processed as desired and programmed.
Although a continuous operation mode has well known advantages over batch operation, there can be conditions which warrant batch handling. The appara-tus of this invention can be used in batch processing. For example, the entire cuvette turntable 74 could be in the form of 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 aliquots, 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 ~orming the cuvett-s, capable of being clamped or snapped onto the upper sur~ace of the turntable. The operation of the apparatus would not be too much different, being re~uired only to enable proper orientation of the replaceable disc to provide sample identi~icatiOn and with some modification which starts and stops the apparatus so that the attendant may remove the used disc and replace it with a new one.
In normal operation $UCh a disc or -turntable would not be required to rotate and its cuvettes would be scanned by the _22-1~38;~Z~

plurality of photometers during rotation of the rotor 56.
Stepping of the disc or turntable 7~ would be useful where the apE~aratus could be alternated between continuous and batch mocles. The removability of the disc on tlle turntable 7~ could S 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 steps carry different sets of filters into the radiation paths.
In a batch method device where the rotor carries a plurality of photom~ters, such photometers could employ individual lamps 50 for each photodetector 62 or a single central source of radiation serving all photometers One variation of the invention could comprise a fixed or ~ndexing 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 an:d 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 S 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 1~38Z20 56 to oscillate by rotating substantially one revolution and then reversing itself to rotate a revolution in the Opposite direction, etc.
Next, with xeference to Figure 5, there will be disclosed both types of data flow and control; first, that which requires two-way cornmunications 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 associated logic unit 106 and 108 to receive or transmit such data.
Since in the now being described embodiment of the -24_ ;

electronics there is to be two-way communications between the data control unit in the reaction table and the master control unit in the control console, the control and data buses 118-12~ 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 embodiments of the transmitters and receivers, as illustrated in Figures 3 and 5, respectively are photoemissive and photosensitive, Figure 4 employs a slip ring assembly 110-116~ however, other 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 closel~ 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.

1~.3R~

Mounted in such a manner close to axis 58, the fact that the transmitter 110 and receiver 11~ are rotating will not cause errors in the binary bit data transmission. On the other hand, i~ the magnitude of a signal, rather than presence or absence thereof, were the measure of the test data 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 from the data control 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 cuvettes from which data i~ desired. As new samples are added to the sample 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 ~ill require the data control unit and its logic unit to have interchanges on the buses 118 and 120 regarding:
the fact 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 buses ~13~ZZ(~

122 and 124 with its logic unit 108 will: acknowledge availability to communicate, receive the identification 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 require 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. Becau~e of thi9 9impler form of con~unications the data buses 120 and 124 need only feed in the direction toward the master control unit, the communications logic unit 106 will operate onl~ 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 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 is located at the axis 58 and comprises a single element tungsten lamp rather than a plurality of lamps positioned 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_ ~.3~ 0 A plurality of lens-containing optical tubes 126 are mounted to the photometer rotor 56 o~ Figure 4 such that one end oE 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 embodiment. The paths or patterns swept by the beams of radiati~n reaching 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 generated thereby and thus easier to regulate the temperature of the cuv~ttes 32. Note that in the embodiment shown in Figure 3 the individual lamps are located quite close to the annular ring defined by the cu~ette 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 single 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 different lamps, even where matched. Whatever happens to the single source lamp 50 happens to all readings made so that the effect is not felt where relative measurements are made. The lamp 50 can be 1~.3~2ZO

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 thè turntab'e 74' which is disposed to move in a path which _29_ ~ ~lA 38 ;~ Z~) carries it and its companion cuvettes through the groove 156 provided in the rotor 56.
There are two photodetectors at 52' and 52" mounted on the rotor 56 in suitable cavities aligned with the mirrors 150 and 152, respectively, and thus aligned to receive the beams 54'b and 54'u against their sensitive surfaces. ~ach 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 10 focussing tube 126' splits, part going through a lower stratum of the liquid 154 and part going through an upper stratum of the same li~uid. The photodetectors 52' and 52" are independent, each providing a different siynal which can be transmitted through suitable connections to data processing 15 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. ~ motor 128 has its drive sha~t 130 20 coupled by a pinion gear 132 to a suitably mating configuration 134 on the periphery of the turntable 74. If 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 ; 25 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 1~1.3~;~20 reaction table 34 and the master control unit 20.
From the above, it now should be understood how the e~ltire 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 components assembly 34.
Since reaction can be monitored at frequent intervals during a prolonged period of 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 same~ In a pre~erred 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 of the chemistry value in the desired concentration units for the test, thereafter feeding the results into the readout unit.
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 of the photometer rotor; however, a stepping device movement can ; 25 be employed. Also, the photometer means are spaced around the circumference of their support, since such positioniny enables a uni~orm weight diskribution around th~ support; however, the photometer means could be mounted with variable spacing especially 1~ 38;~20 -if the path of motion i5 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 insertiny 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.

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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

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 members 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 non-rotatably 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 plurality of photometers arranged on said rotor and each including a photoresponsive element and there being radiant energy source means serving all of the photo-responsive elements and directing a beam of radiant energy to each of them whereby there is at least one beam for each element,/each beam having a fixed orientation rela-tive to its associated photoresponsive element that is maintained at all times during rotation of the rotor, /the source means and elements being geometrically arranged in a radial configuration around the rotor,/land the beams being so located that each will be intercepted by all of the sample members in sequence during rotation of the rotor, E. means for driving the rotor in a rotary movement, F. the photoresponsive elements being responsive to the beams to produce electrical signals when intercepted by sample support members, the signals being related to the chemical conditions of sample substance, if any, carried by the respective sample support members, G. means for generating usable data from any such signals associated with said support structure and non-rotatable carrier, and H. means for coupling the signals from the rotor to said last mentioned means.

2. The apparatus as claimed in claim 1 in which the sample support member carrier is wholly removable from the support structure to enable replacement thereof by another such carrier.

3. The apparatus as claimed in claim 1 or 2 in which the source means comprise a single lamp in the center of the rotor and each beam emanates from said lamp.

4. The apparatus as claimed in claim 1 or 2 in which the source means comprise a lamp associated with each photo-meter, the movement of the rotor resulting in the sample sup-port members being brought between the lamps and the photo-responsive element of each photometer.

5. The apparatus as claimed in claim I or 2 in which an A/D converter is mounted on said rotor between each re-spective photoresponsive element and said coupling means where-by the photoresponsive elements pass analog signals while said coupling means pass digital signals.

6. The apparatus as claimed in claim 1 or 2 in which each sample support member comprises a cuvette having at least one wall which is capable of transmitting radiant energy, said cuvette is adapted to hold a liquid sample and in which each beam of radiant energy is arranged to pass through said wall and at least through a portion of the liquid sample, if any, in said cuvette and thence to the photoresponsive element as-sociated with said each beam.

7. The apparatus as claimed in claim 1 in which said first plane is horizontal and said axis is vertical.

8. The apparatus as claimed in claim 1 in which a second wall of each cuvette opposite said one wall is also capable of transmitting radiant energy and the photoresponsive element associated with each beam is arranged to receive the radiant energy emerging from each second wall in sequence.

9. The apparatus is claimed in claim 8 in which the beam, its associated photoresponsive element and the source are in rectilinear alignment.