LIQUID LIGHT TUBE END CAP ASSEMBLY

Abstract: Liquid light tube (guide) end cap assembly (155, 156) particularly useful in a system (10) for the clinical analyses of liquid biological samples for directing wavelengths of light. The assembly (155, 156) comprises a light guide (155) having projecting at one end portion thereof a quartz member (157) and a housing (156) for containing the end portion of the light guide (155) and the quartz member (157), thereby forming an aperture (159) between the quartz member (157) and the housing (156), the aperture (159) having a depth of between about 0.002 and 0.007 inches.

Description: 477 -1- lQilXD IxlSSl ΪI2&E CAP ASSEMBLE BACKGROUND ££ 3BE INVENTION I Eisl Qi. tn≤ Invention Tnis invention relates general ly to the analysis of materials^ and more particularly to a new arrangement or the end portion of a light guide tube which directs light to a pnotospectrometer f rom a l iquid sample located in a cuv ette. The present inv ention is particularly useful in automated chemistry analyzers wnich are employed for determining the presence and l ev el s of one or more sel ected constituents in relatively small biological liquid samples. II Description £j÷ £jlS PxifiX ΔJ t Numerous automated clinical analyzers are know and widely used in nospital clinical laboratories. An example of such an analyzer is the multi-cnannel type analyzer. A multi-channel analyzer is one in which a series of different tests are performed simultaneously by the anaiyzer, and in parallel with one another. Such an analyzer can be best visualized as a series of batch analyzers operating in parallel wherein each channel performs a single analysis test. The multi-channel type analyzer generally utilizes a liquid reagent to react with tne particular constituent being tested in tne sample and a photo-optical system to read the optical absorbence of the sample which corresponds to tne level of tne constituent in the sample. Altnough this type of automated analyzer has received wide acceptance in the clinical laboratory, certain drawbacks are associated with its use. For example, altnougn tne multi-cnannel type analyzer is reliable due to its simplicity, cost effective for large number of samples and nas a relatively hign test througnput rate, it is limited in the sense that it can only be effectively utilized to perform a single constituent analysis at a time on a relatively large number of samples. In addition, sucn analyzers are not capable of performing emergency "stat" tests due to their relatively long and complex set up time and their innerent inability to economically analyze a single test sample. Tnus, the efficiency of tnis type of system is not the best. A furtner significant disadvantage found is that altnougn tests can be simultaneously performed for multiple constituents on the same sample, generally all of tnese tests must be performed for every sample -3- whether desired or not. This results in a waste of botn sample material and the reagents used in the unnecessary tests. Furthermore, due to the fact that multiple discrete and dedicated channels are utilized in sucn an instrument, there is significant duplication of numerous components wnich adds to the complexity and expense of the overall instrument. An automated single track clinical analyzer which avoids tne above-described drawbacks is described in commonly owned U.S. Patent Application Serial- No. 284,840, filed July 20, 1981 entitled, "Automated Analysis Instrument System", the disclosure of which is nereby incorporated by reference in its entirety. Furtnermore, by using a unique pnoto-optical system, described in commonly owned U.S. Patent Application Serial No. 284,841, filed July 20, 1982 entitled, "Multichannel Spectrophotometer", the disclosure of wnich is nereby incorporated by reference in its entirety, greater flexibility of analysis at each analysis station is achieved. This is because this pnoto-optical system employs fiber optica bundles or similar lignt guides to transmit variable wavelengths of light to each analysis station from a single light source. The single track analyzer utilizes a disposable cuvette belt formed from tnin plastic film and defines a series of discrete reaction compartments (cuvettes) which are transported in line anead through the instrument. Such a cuvette belt is described in commonly owned U.S. Patent Application Serial No.284,842, filed July 20, 1981 entitled, "Cuvette System For Automated Chemical Analyzers". Tnis belt provides handling flexibility and avoids tne cross-contamination associated with flow-tnrougn cuvettes as well as avoiding the washing required for reusable cuvettes. In employing a pnoto-optical system for critical analysis work, it is very important that there be substantially no interference witn the patn of light tnat is directed from the sample being analyzed through a lignt tube wnicn in turn directs the light to a pnotospectrometer. Any interference with this light patn can erfect tne accuracy of the analysis, and lead to incorrect results. However, it is typical in may of tne prior art analysis systems that a good deal of "noise" is received from the light signal sent to a pnotospectrometer from a sample being analyzed. This noise causes a scattering of the test results. Also, tne test results tend to "float". Wnen using a series of pnotospectrometers in an analysis system there is a tendency to avoid focussing of the lignt signal to tne pnotospectrometers tnereby introducing tracking errors from one analyzer to anotner analyzer. Tne end result of all of tnese problems is that the level of accuracy of tne analysis is reduced. SIM B1 Q£ XBfi INVENTION It is tnere ore an obj ect of the present invention to overcome tne disadvantages of many of the analysis systems employing pnoto-optical systems as disclosed by tne prior art. It is an ooj ect of the present invention to provide a pnoto-optical analysis system tnat employs unique light guides to transmit various wavelengths of l ight to each analysis station from a single lignt source. It is to oe noted tnat the term "light" as used herein should be considered in its broadest sense to include both visible wavelengths and non-visible spectral analysis wavelengths. It is a furtner obj ect of the present inv ention to provide a pnoto-optical analysis system tnat employs a unique structure for tne systems l ignt tube which substantial ly improves botn tne precision of tne readings be ing obtained and the accu racy of the analysis being sought. It is a further obj ect of the present invention to provide a pnoto-optical analysis system that employs a unique structure for the systems l ight tube that prevents any scratching or abrasion of the l ight tube oy a pass ing cuv ette in which the sampl e being analyzed is contained. It is stil l a further obj ect of the present invention to provide a pnoto-optical analysis system that employs a unique structure for tne systems light tube that prevents interference with the path of the light from the sample being analyzed to the photospectrometer by shortening tne amount (distance) of bath water that the lignt passes tnrough in traveling from the sample being ana lyzed to the l ignt tube. Tnis substantial ly prevents the formation of bubbles or lodging of debris in tne open space area between tne l ignt tube and the cuvette containing tne sample. Tne f oregoing obj ects and otners are accomplisned in accordance with the present invention by providing an automated instr ument system f o r analyz ing -tne constituents of a specimen sample wherein the sampl e is contained in a cuvette and l ight is directed to the sampl e, into a l ight guide and to a photo-optical system for analyzing tne sampl e, the system employing an improved light guide assembly. The improved l ight guide assembly comprises a l ight guide having proj ecting at one end portion thereof a quartz member and a nousing for containing tne end portion of the l ignt guide and the quartz member. The critical improvement of tnis invention (which includes a lignt guide assembly as described herein that can be used in an automated instrument system for analysis and which avoids the disadvantages outl ined above) l ies in f orming an aperture between the quartz member and the nousing, the aperture having a depth of about 0.002 to 0.007 incnes. fiRIEE DESCRIPTION Q£ 2HE DRAWINGS For a better understanding of the invention as well as otner objects and further features tnereof, reference is made to the following detailed disclosure of this invention taken in conjunction with the accompanying drawings wnerein: Figure 1 is a schematic plan view of an automated clinical analyzer that can incorporate the features of tne present invention; Figure 2 is a partial perspective view of the automated clinical analyzer snown in Figure 1; Figure 3 is a perspective view of a cuvette belt for use in tne clinical analyzer of Figure 1 and 2; Figure 4 is a partial schematic representation of a preferred pnoto-optical system utilized with the analysis system of Figures 1 and 2; Figure 5 is a plan view of an end portion of a light guide assembly as described in tne prior art; Figure 6 is a plan view of an end portion of a light guide assembly in accordance with the features of the present invention; and Figure 7 is a plan view illustrating the positioning of a cuvette oetween two light guide end caps. DESCRIPTION Q∑ iflfi PREFERRED EMBODIMENTS Figures 1 and 2 illustrate as one example, an automated clinical analyzer 10 as generally described in commonly owned U.S. Patent Application Serial No. 575,924, filed February 1, 1984 and entitled "Clinical Analysis Systems and Methods", that can incorporate the features of tne present invention. More particularly, the analyzer is Paramax Analytical System as manufactured by American Hospital Supply Corporation. The analyzer 10 is particularly adapted for tne testing of constituents in biological fluids, such as blood samples. The analyzer comprises a series of processing stations past wnicn strips of disposable reaction cuvettes are indexed or advanced. Tne cuvettes 24 are supplied from a supply reel 20 as a continuous cuvette belt 22 and are indexed through the analyzer by tractor conveyor 30 wnicn engages a row of index noles in tne cuvette belt. The cuvettes are indexed in turn past the following stations: a belt cutter 28 for dividing the belt into sections; a tabletted reagent dispenser 40; a diluent and liquid reagent dispenser 50; an ultrasonic mixing horn 14; a sample dispenser 80 for dispensing biological samples delivered by a transfer carousel 64; an air jet mixing apparatus 15 including an apparatus for squeezing the top (opening) of the cuvette during the air jet mixing process as described in commonly owned U.S. Patent Application Serial No. 858,366, filed April 30, 1986 entitled, "Improved Clinical Analysis Methods and Systems" eight photometric read stations 90; a further reagent dispenser 54; a further air jet mixing apparatus 15a for mixing the sample and the further reagent; a cuvette sealer 26 and a cuvette collection station 18. During their passage through the analyzer, the cuvettes are carried in a water bath 12 maintained at a constant temperature. The cuvette belt 22 is preferably constructed and made in the manner more f ul ly described in the aforesaid U.S. Patent Appl ication Serial No. 284 ,842. As shown in Figure 3 , the belt 22 comprises two strips 111 , 112 of transparent f l exibl e pl astic material which are mo ul ded and seal ed together to fo rm a se ries of discrete, side-by-side paral lel compartments (cuvettes) 24 separated by webs 115. The compartments are closed at one end and have a top or opening or open mouth 117 at the other end so as to receive and retain f luid therein. For example, the cuvettes can be in the order of size so as to be capabl e of holding about 500 microliters of fluid. The flat web material 115 between the vessel s 24 includes a transport strip portion extending alongside the cl osed ends thereof wnicn is formed with indexing perforations or holes 26. Tnese perforations are engaged by the tractor transport 30 of tne analyzer 10 for conveying the cuvettes tneretnrougn and maintaining a precise alignment of the optical patns through the cuvettes with the photo- optical examining system at analysis stations 90. The transport 30 comprises a single continuous guide and support track extending tnrougn the analyzer having a main tractor belt 32 which engages the indexing holes 26 in tne cuvette belt 22 and advances the cuvettes tnrougn the instrument at a predetermined rate of advance. A snort loading belt 34 threads tne cuvette belt 22 into engagement with the main tractor belt 32. Tne transport 30 advances or indexes tne cuvettes tnrougn the analyzer 10 in steps corresponding to the spacing between cuvettes (the pitch of the belt) with tne cuvettes being stopped and held stationary for a dwell period between each advance. Each step may suitably correspond to a time interval of 5 seconds witn a 4 second dwell time between each indexing advance of tne cuvettes. Tne reagent tablet dispenser carousel 42 comprises a circular array of tabietted reagent dispensers 40 and cna be rotated to bring the correct solid reagent dispenser to solid reagent dispensing point "SRD" to drop a single reagent tablet 44 into a cuvette 24. As illustrated, tne carousel 42 accommodates thirty-two reagent taolet dispensers 40. It is rotated under microprocessor control to bring the correct tablet dispenser to the dispensing point for each cuvette. Tne dispensers 40 are detachable and can be loaded randomly. An automatic flagging system indicates when a dispenser is low in tablets. Tne diluent and/or liquid reagent dispenser 50 is located adjacent to carousel 42 for adding sufficient diluent 52 for reagent tablet 44 dissolution and/or for dispensing a liquid reagent into the reaction vessel (cuvette) 24 at point "LDD \"* Tne ultrasonic horn 14 acts on the cuvette contents for a sufficient l ength of time; for exampl e, 45 seconds, to totally dissolve tne reagent tablets. A sample loading and transfer carousel assembly 60 is l ocated downstream of the reagent and di luent dispensers. Tnis carousel assembly comprises a loading carousel 62 into whicn patient samples 70 are randomly l oaded; a transfer carousel 64 which accepts . the patient samples 70 from loading carousel 62, identifies tne patient sampl e by means of a bar code reader 66 wnicn reads a bar code label 72 pl aced on the patient sample container and continuously feeds the patient samples into the system; and f inal ly, an unloading carousel 68 receives the patient samples 70 after testing and stores them in an organized manner in the event tnat tney must later be located and retrieved. The l oading carousel 62 permits continuous random l oading of up to 96 patient sampl es. The transf er carousel 64 continuously feeds patient samples into the sys tem f or maximum tnroughput. Standard col l ection tubes or micro sampl es tubes may be accommodated thus al l owing util ization of the same containers in which tne sampl e is col l ected; f or exampl e, in the case of blood samples, the "Vacutainer" tube which is commonly used to draw the serum specimen. Sample 80 for dispensing samples into the cuvettes 24 at point "SD" is located adjacent to transfer carousel 64. Tnis sampler is designed to aspirate about 2 to 20 microuters of patient sample 70 from its container in tne transfer carousel and dispense it into a cuvette 24 during tne four second dwell period while the cuvette is aligned witn the sampler. The air jet mixing apparatus 15 (and 15a) direct an air jet preferably at an acute angle against the liquid surface in the cuvette adjacent its junction with the cuvette wall to create a vortex thus producing a tnorougn mixing of the sample with the reagent and diluent in accordance with the teachings of the system as described in the aforesaid U.S. Patent Application No. 575,924. In a preferred embodiment, the apparatus nas a fixed, inclined nozzle 150 and the cuvettes 24 are aligned in position beneath the nozzle and the air jet is switcned on only during the dwell period when tne cuvette is stationery. In order to ensure that the air j et correctly strikes the liquid surf ace, the l iquid level is closely controlled. Eignt pnotometric analysis stations 90 are located at points "SA1" tnrougn "SA8" along the cuvette track 30. Tnese analysis stations are connected by individual optical guides 92 and 94 to photo-optical system 100. Tne station "SAl" is arranged fol lowing the ultrasonic norn 14 for verifying proper reagent dispensing and dissolution. This system is il lustrated in Figure 4. Tne pnoto-optical system comprises a singl e light source 101 for generating sel ected wavel engths of l ight. The output of l ight source 101 is focused by f ixed f ocusing l ens 102 onto the mul tipl e wavel ength selective filters disposed about the circumference of rotary source filter wheel 103. The rotation of source filter wneel 103 is regulated by the instrument control microprocessor through double shafted motor 104. The output f rom source f ilter wheel 103 is sequential ly transmitted tnrougn separate light guides 92 to each of tne analysis stations. At tne analysis stations, the filtered l ight energy is passed tnrougn tne reaction compartment 24 containing tne mixture to be analyzed. Tne output of the analysis stations is then passed back to the photo-optical system 100 via separate l ight guides 94. At this point, a second filter wheel 107, which preferably is identical to and synchronized with source filter wheel 103, intercepts the outputs of light guides 94 before tnis output is directed to a separate pnotodetector tube 109 for each analysis station. A reflector 108 may be utilized to focus tne output of filter wheel 107 on pnotodetector tubes 109. In the representation of Figure 4, only one set of light guides 92, 94 and one pnotodetector tube 109 is shown for simplicity, altnougn it is to be understood that eight of these elements (one for each analysis station) are required. Tne outputs of photodetector tubes 109 are monitored by the control microprocessor and appropriate wavelength output values for each analysis reaction at eacn analysis station is stored by the microprocessor. nen tne reaction is completed, the microprocessor will utilize tnis stored inf ormation to cal culate the concentration of the selected sampl e constituent and provide tnis result to the instrument operator. As can be seem from Figure 4, each f ilter wheel has seven different wavelength selective filters 105 disposed about its circum erence. In addition, an opaque blank 106 is l ocated thereon in order to establ ish the residual "dark current" l evel of the electronics. Hence, great flexibility is provided by permitting any one or combination of the seven wavelengtns to be read at any analysis station for any sample during tne four second analysis period. In that f il ter wneels 103 , 107 are rotated at thirty revolutions per second in the pref erred embodiment. thirty readings at a particular wavelength may be made eacn second whicn can then be averaged to prov ide a nignly accurate final value by the microprocessor. Tne second reagent dispenser 54 permits f urthe r reaction of the sample to be obtained following initial testing and is shown arranged between analysis stations "SA4 " and "SA5 ". It could be l ocated between any of tne analysis stations "SA2" to "SA8". This capacity for optional reagent additions or triggered reaction capability gives added analytical versatili ty for multiple reagent test situations. Tne furtner air j et mixing apparatus 15a provides f or tnorougn remixing of the cuvette contents fol l owing addition of further reagent at station 54. Tne cuv ette sealer 16 seals the tops of the tested cuvettes for convenient cl ean disposal of compl eted samples at tne cuvette disposal location where they are neatly collected into a lined disposal bin. Tne microprocessor control system of the cl inical analyzer, which suitably has a 280 processing unit, controls al l tne operating units thereof in accordance with sample and test information inputted at a suitable operator interface keyboard. In accordance with the desired test results, quantities of a single sample may be dispensed into one or more cuvettes either alone or in combination with any one or more of the sol id and liquid reagents and diluents, and examined at any one or more of tne analysis stations 90. Test results are displayed on a screen and can be printed out. Turning now specifically to the unique features of the present invention, there is shown in Figures 5 a typical end portion of a light guide assembly as described in the prior art. In comparison there is snown in Figure 6 an end portion of a light guide assembly in accordance with the features of the present invention suitable for use as the end portion of optical guides 92 and 94 (see Figure 4) in the automated clinical analyzer described above at analysis station 90. Tne prior art generally describes light guide assemblies for clinical analyzers that employ end caps and liquid light tubes having the basic configuration as illustrated in Figure 5. A known assembly includes a light guide in tne form of a liquid light tube 150 tnat is encased by a nousing 151 up to the end cap area. Tne end cap is joined onto the liquid light tube 150 and contains a quartz member 152 and an aperture 153. Since the entire assembly is immersed in a water batn (tnis is typical of this type of light guide assembly wnen used in a clinical analyzer as described nereinabove) , the water fills the aperture and space inside the end cap leading up to the end face of quartz member 152. During the analysis procedure, light is passed tnrough a cuvette having the sample being analyzed therein, through tne length of bath water in tne aperture 153, into and through the quartz member 152 and into and through the light tube 150. Specifically, because of the aperture arrangement and tne length (distance) the light must travel in the water to get from the sample in the cuvette to the quartz member, there is a great tendency to form bubbles and trap debris in the aperture. Both the bubbles and the debris substantially interfere with the critical accuracy of tne analysis. The prior art light guide assembly introduces a good deal of noise in the signal tnat is received by the photospectrometer which causes scattering of the test results. Also, the test results tend to float thereby decreasing the overall accuracy of the analysis results. Tne problems and disadvantages of the prior art light guide assembly as described hereinabove have been overcome by tne lignt guide assembly having the features of the present invention and as shown in Figure 6. The lignt guide assembly in accordance with tne present invention includes a light guide in the form of a light tube 155 tnat is encased by a housing 156 up to the end cap area. It is preferred that the lignt tubes employed are commercially available liquid light tubes. Installed on the end of the light tube 155 is quartz end member 157. The purpose of the quartz end member is to provide a wear-resistant component relative to the bath water which is not biodegradable and which nas excellent optical characteristics. The quartz member provides all such advantages. It was recognized and appreciated by the present invention that placement of quartz member 157 relative to tne end cap (and cuvette) was critical to the accuracy of the clinical analyzer which employed such a light guide on its optical guides (e.g. light guides 92 and 94 of Figure 4). The light guide assembly shown in Figure 6 places the cuvette end of the quartz member up against the back side of the wear plate 158 of the end cap and thereby provides an aperature 159 naving a depth that is kept between 0.002 and 0.007 inches; which distance is critical to tne present invention. By placing the end of tne quartz member close to the inside of the end cap, the path of lignt through the bath water is precisely limited to tne deptn of the aperature, i.e. 0.002 to 0.007 inches. By maintaining this critical aperature depth in the light guide assembly during the analysis process, a dramatic improvement in the accuracy of the photospectrometer test results is achieved from analysis machine to analysis machine. This is provided by a combination of the accurate control of the size of the aperature depth in the light guide end cap and the resulting short length of bath water that the light path must pass through between the cuvette wall and quartz member 157. As shown in Figure 7, during the analysis process cuvettes 160 pass through a channel formed by two light fluid end caps 161 and 162 (each of which incorporate tne features of the present invention) when the f luid in the cuv ette is read by the photospectrometer. Cuvette walls are generally formed in a convex manner (outwardly snaped) . To remove any space between the end caps 161 and 162 and each cuvette 160, and insure imp ro v ed l ength cont r o l ( t he r e by pr ev ent i ng interf erence with the accuracy of the readings by the pnotospectrometer) the cuvette walls are made parallel to eacn otner by the end caps. Tni s arrangement enables the cuvette wal ls to be aligned horizontally by tne light guide end caps and vertical ly by the index noles (item 26 of Figure 3) in the cuvette belt during analysis. In accordance with the preferred features of the present invention in order to provide a high level of accuracy with regard to the analysis resul ts, the distance A between the l ight guide end caps 161 and 162 during analysis should . be preferably maintained at about 0.195 inches ± 0.001 to keep the cuvette wal ls substantially flat and thereby improve the accuracy of the analysis. By empl oying such a precise geometric arrangement of the cuvettes between tne light guide end caps in accordance with the critical features of the present inv ention, al l of pnotospectrometers act as one photospectrometer Furthermore, by shortening the depth of tne light guide end cap and therefore the amount (distance) of batn water that the light passes through in accordance witn the critical parameters described nereinabove, there is basically no chance that bubbles or debris will be present or get trapped in the aperature. Providing the critical geometric structure to the light guide end cap in accordance with the present invention would provide for each analyzer is a clinical analysis system as described hereinabove to be so focussed automatically with regard to the light signal thereby substantially eliminating tracking error from analyzer to analyzer. It should be understood that the above described embodiments of the invention are illustrative only, and that modifications thereof may occur to those skilled in tne art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed nerein, but is to be limited only as defined by the appended claims.

Claims: C AIliS 1. In an automated instrument system for analyzing the constituents of a specimen sample wherein the sample is contained in a cuvette and light is directed to the sampl e, into a light guide and to a pnoto-optical system for analyzing the sampl e, an improved light guide assembly comprising a light guide having projecting at one end portion thereof a quartz member and a housing for containing the end portion of tne l ignt guide and the quartz member forming an aperature between the quartz member and the housing, tne aperture having a depth of between about 0.002 and 0.007 incnes. 2. Tne system of Claim 1 wherein said l ight guide assembly and cuvette are disposed in a water bath f or maintaining said sampl e at a predete rmined temperature. 3. Tne system of Cl aim 1 wherein said analysis system includes a plurality of analysis stations each employing said improved l ight guide assembly. 4. The system of Cl aim 3 wherein said photo-optical system comprises a single light source for generating selected wavelengths of light and separate light guides for transmitting said wavelengths to eacn of said analysis stations. 5. Tne system of Claim 1 wherein said l ight guide is a fluid filled light pipe. 6. The system of Cl aim 1 wherein said cuvette is positioned between two of said improved l ight guide end assembl ies during said analyzing process. 7. The system of Cl aim 1 wherein the distance between said light guide end assemblies is about 0.195 ± 0.001 inches. 8. Tne system of Claim 6 wherein the walls of said cuvette are made substantially parallel by said l ight guides when said cuvette is positioned between said light guide assembl ies during analysis of said sample. 9. Tne system of Cl aim 1 wherein said sample is a liquid. 10. The system of Cl aim 1 wherein the said photo-optical system includes a spectrometer. 11. A light guide assembly for directing wavelengths of light comprising a light guide having proj ecting at one end portion thereof a quartz member and a housing for containing the end portion of the lignt guide and the quartz member, thereby forming an aperture between the quartz member and the housing, the aperture having a depth of between about 0.002 and 0.007 inches. 12. The assembly of Cl aim 11 disposed in a water bath. 13. The assembly of Cl aim 11 wherein said lignt guide is a fluid filled light pipe.

Inventors: ELBERT LAWRENCE EMIL, HECKER RAYMOND LOUIS, MAZZA JOHN C, ELBERT, LAWRENCE, EMIL, HECKER, RAYMOND, LOUIS, MAZZA, JOHN, C.
Applicants: BAXTER TRAVENOL LAB, BAXTER TRAVENOL LABORATORIES, INC.
Application year: 1987
Main classification: G02B6
IPC codes: G01N21, G01N35, G02B6