CUVETTE AND CUVETTE CARTRIDGE FOR A CHEMICAL ANALYZER

Abstract: A disposable cuvette (10) is molded of rigid transparent plastic resin that is impervious to liquids to be handled within it. The cuvette (10) has a rectangular cross section. Identical side walls (45) extend between upper and lower ends of each cuvette, the upper end (52) being open for reception of liquids and the lower end being closed. Recessed optical surface areas (48-50) at the lower end are perpendicular to one another for optical testing of the cuvette contents. An elongated cartridge (40) holds a stack of abutting cuvettes (10) to facilitate their handling.

Description: DESCRIPTION CUVETTE AND CUVETTE CARTRIDGE FOR A CHEMICAL ANALYZER Technical Field This disclosure pertains to a cuvette designed for use in a clinical chemistry analyzer for the testing of patient samples, such as blood or urine. Background Art Automated analyzers have been developed for biochemical analysis of patient samples, such as whole blood, serum, urine, plasma and cerebral spinal fluid. Such analyzers carry out tests for assays in defined or random sequences of operations designed for efficient, high volume test procedures. They typically involve use of a reaction turntable that holds mixtures of reagents and samples within receiving cuvettes. Liquid materials are inserted into the cuvettes from a movable pipette. They are mixed and centrifuged for optical analytical test purposes. Much of such equipment is geared to very high volume test procedures. In such analyzers, the cuvettes are generally multi-compartment elements that partially or completely meet the requirements of a turntable. Many of these cuvettes are reusable. Individual cuvettes are also used on such turntables. They have assumed the form of vertical containers similar to cylindrical or rectangular test tubes. The present cuvette is designed for use as a disposable item, each cuvette handling a single mixture of sample and reagent for analytical purposes. The cuvettes are designed for use in an angularly inclined position on a complementary turntable, which facilitates insertion of new cuvettes from the center of the turntable and ejection of spent cuvettes from its periphery. Details of the invention will be understood from the accompanying drawings and text. Brief Description of the Drawings Fig. 1 is a side elevation view of a cuvette; Fig. 2 is a top view; Fig. 3 is a sectional elevation view taken along line 3-3 in Fig. 2; Fig. 4 is a front elevation view of a loaded cuvette cartridge; Fig. 5 is a transverse sectional view through a loaded cartridge as seen along line 5-5 in Fig. 4; Fig. 6 is a plan view of the cuvette turntable; and Fig. 7 is an enlarged sectional view taken along line 7-7 in Fig. 6. Best Modes for Carrying Out the Invention and Disclosure of Invention The automatic chemical analyzer for which this cuvette was designed includes a turntable 11 rotatably mounted about a vertical axis. A plurality of disposable cuvettes 10 are releasably mounted to the turntable 11. A motor is operably connected to turntable 11 for alternately (1) indexing it at a stationary angular position about its axis with a selected cuvette 10 positioned at a cuvette access station or (2) turning it about its axis while mixing or centrifuging the contents of cuvettes mounted to it. An analytical means, such as an optical system, is provided adjacent to the turntable 11 for performing tests on the contents of the cuvettes 10 as they rotate about the turntable axis. The analyzer also includes a vertical probe arm (not shown) movable about a vertical axis. The probe arm supports a downwardly-extending open pipette for movement along an arcuate path intersecting both the cuvette access station and a container access station where regents and samples are supplied to the open end of the pipette. It can move along the arcuate path in a random fashion to transfer liquid from a container positioned at the container access station to a cuvette 10 positioned on the turntable 11 at the cuvette access station. The disposable cuvettes 10 designed for use in turntable 11 are illustrated in detail in Figs. 1-3. A complementary cartridge 40 for handling and storing the cuvettes is shown in Figs. 4 and 5. Cuvettes 10 are molded from a suitable transparent rigid plastic material that is liquid impervious and inert to the liquids which they are to contain. The cross-sectional configuration of each cuvette is rectangular. Each cuvette 10 includes two identical side walls 45 having parallel top and bottom edges. The straight top and bottom edges along each side wall 45 longitudinally overlap one another to facilitate stacking of the cuvettes in abutting parallel positions. Side walls 45 are transversely joined by parallel spaced top and bottom walls 46 and 47. One end of each cuvette 10, termed its "upper end", includes an opening 52 between the end edges of the side walls 45. Opening 52 provides access to the interior of cuvette 10 for receipt of liquids. The edges of side walls 45 that form the opening 52 include angular edges intersecting the straight top edges of the respective side walls 45. The angular edges assume horizontal orientations when positioned in turntable 11 (Fig. 7). The end edges along the opening 52 are perpendicular to the top and bottom walls 46 and 47. The opening of cuvettes that are pre-loaded with reagents or other materials before use in the chemistry instrument 24 can optionally be sealed by a suitable film or other cover (not shown) capable of being pierced by the descending tip of pipette 18. The opposite end of each cuvette 10, termed its "lower end", includes perpendicular optical surfaces for transmission of light in conjunction with operation of the optical system 14. These surfaces include top, end and bottom optical surfaces 48, 49 and 50, respectively. Each optical surface area is slightly recessed inwardly from the outer edges of side walls 45 to protect the optical surfaces from abrasion or contact during handling. The lower end of each cuvette 10 has a transverse protruding ledge 68 extending across the two side walls 45. Ledge 68 provides a continuous transverse surface for abutment of the upper end of an adjacent cuvette 10 when one cuvette pushes another into position within turntable 11. A small downwardly-facing recess 51 is provided within the bottom wall 47 of each cuvette 10 next to the inner end of lower optical surface 50. The recess 51 serves as a detent in conjunction with a spring-biased enlargement on a spring member 55 (see Fig. 7) that yieldably holds cuvette 10 within a receiving compartment on the turntable 11. The cuvettes are preferably packaged within elongated disposable cartridges 40 (see Figs. 4 and 5). The parallel stacked cuvettes 10 face oppositely at the respective ends of cartridge 40. The cartridge 40 is designed for insertion into an open slot of a receiving cuvette magazine (not shown). The cuvette cartridge 40 is formed from a C-shaped channel 41 having interior surfaces complementary to the exterior shape and size of the individual cuvettes 10. Cartridge 40 can be formed from any suitable stiff, resilient plastic sheet or can be extruded in the shape illustrated in Figs. 4 and 5. Its purpose is to facilitate handling and storage of the large quantities of cuvettes 10 required by each chemistry instrument. It expedites manual entry of cuvettes 10 into a storage magazine included within the instrument. Cuvettes 10 fit transversely within the elongated channel 41 in abutting parallel positions within two groups. Each group of cuvettes 10 at the respective ends of cartridge 40 can be identical to a full stack of cuvettes within the receiving magazine. Two pairs of inwardly bent stops 42 near the center of cartridge 40 limit inward motion of cuvettes along the length of the magazine. Outward movement of cuvettes at each end of the cartridge 40 is resisted by smaller end stops 43. The stops 43 are bent inwardly to partially intersect the path of cuvettes 10 as they exit the cartridge 40. Turntable 11 is detailed in Figs. 6 and 7. It includes a circular, radially- slotted wheel adapted to be rotatably mounted about a vertical axis. The outer periphery of the turntable 11 presents a series of equiangularly spaced radial compartments 53. Each compartment 53 individually receives a cuvette 10 in the manner shown in Fig. 7. Each compartment 53 includes a radial slot having an interior cross-sectional shape and size that complements the exterior cross-sectional shape and size of a cuvette 10. The compartments 53 are arranged about turntable 11 at an angle such that the angular upper edge of each cuvette opening will be oriented horizontally. The angular upper edge is also perpendicular to the turntable axis. The angular nature of each compartment also positions the optical end of each cuvette 10 at a lower elevation than opening 52, assuring that liquids in each cuvette will not spill, even while turntable 11 is stationary. An axial slot 54 intersects each compartment 53 across its outer end. Slots 54 extend through the upper and lower surfaces of the turntable 11. They provide light access to the optical surfaces 48-50 of cuvettes 10. Slots 54 permit passage of light through the individual cuvettes 10. They are used in conjunction with operation of an optical system (not shown) to facilitate photometric testing of cuvette contents while within the turntable 11. The cuvettes are yieldably held within the radial compartments 53 by spring 55 (Fig. 7). The outer ends 61 of the longitudinal springs 55 are enlarged to enable them to fit within the recesses 51 formed in the cuvettes 10. The spring ends 61 radially position each cuvette 10 within the respective turntable compartments 53. Springs 55 also serve as interior supports within compartments 53. They yieldably maintain the top walls 46 of cuvettes 10 in engagement with the upper inside surfaces of the compartments 53. The cover 59 about turntable 11 is fabricated of an electrically conductive plastic material. Springs 55 maintain firm surface-to-surface contact between the top wall 46 of each cuvette 10 and the interior surface of cover 59. This provides effective heat transfer to each cuvette to reduce the time required to warm it in preparation for receipt of a test sample. The cover 59 can be heated as the turntable 11 is rotated, using an adjacent stationary source of controlled heat (not shown). Cuvettes 10 held within the turntable 11 are individually accessible and remain open for reception of samples and reagents as required by requisitioned assays. Liquids can be introduced through the openings 52 of the respective cuvettes 10 by operation of a movable probe arm and pipette (not shown) at a cuvette access station. All incubation of samples involved in an assay can occur within cuvettes 10 while positioned within turntable 11. The upper surface of the supporting central plate 56 on turntable 11 has a plurality of tapered radial guide surfaces 57 formed about it. Surfaces 57 are centered between each radial compartment 53 and are obliquely aligned with the respective compartments 53. They are used to index turntable 11 during reception of incoming cuvettes. As can be seen in Fig. 7, the turntable 11 holds cuvettes 10 in elevationally tilted radial positions within the individual receptacles 53. Their openings 52 of the cuvettes 10 are exposed in the turntable 11 for reception of liquid materials. Their optical surfaces 48, 49 and 50 are exposed through slots 54 at the periphery of turntable 11 for transmission of light as required by operation of the related optical system. The combination of the angular orientation of the cuvettes 10 within the receptacles 53 of turntable 11 and the provision of the elongated opening 52 across the upper end of each cuvette 10 provides an open access area to the interiors of the installed cuvettes 10 that does not permit splashing of fluids as they are delivered through a vertical pipette. The inclined angular positioning of cuvettes 10 within the individual receptacles 53 in the turntable 11 also prevents splashing or loss of fluids from within the cuvettes 10 during mixing operations that can be carried out by operation of the turntable 11. Extending the cuvette opening 52 along one side of each cuvette is an improvement specifically adapted to the angular cuvette orientation utilized in the illustrated turntable 11. The inclined angular orientation of the individual cuvettes 10 within the receiving turntable shown in Figs. 6 and 7 allows each cuvette to be installed by pushing it radially outward from the center of the turntable 11 in a "feedthrough" arrangement, as indicated by arrow 60. As a new cuvette 10 takes its place within a selected receptacle of the turntable 11, the preceding cuvette will be serially pushed from the turntable 11, as indicated by arrow 62.

Claims: Claims 1. A cuvette (10) for use in a chemical analyzer, in which the cuvette (10) is integrally molded from rigid liquid impervious material in a hollow rectangular cross sectional configuration, the cuvette (10) being characterized by: two parallel side walls (45) arranged in transversely spaced positions extending between opposed ends of the cuvette (10), each side wall (45) having top and bottom edges and two end edges arranged across the respective ends of the cuvette (10); one end of the cuvette (10) having an opening (52) extending across its end edges and continuing between the top edges of the side walls (45) to permit entrance of the tip of a vertical pipette into the one end of the cuvette (10) while the side walls (45) are in vertical positions and the angular edges are in horizontal positions with the top and bottom edges inclined at an angle to the horizontal; the remaining end of the cuvette (10) being closed by an end wall formed across the two side walls (45); a top wall (46) joining the end wall and the respective top edges of the two side walls (45); a bottom wall (47) joining the end wall and the respective top edges of the two side walls (45); and optical surface areas (48-50) provided at the remaining end of the cuvette for transmission of light during optical testing of cuvette contents. 2. The cuvette of claim 1, wherein the top and bottom walls (46, 47) are further characterized by parallel sections leading from the opening (52) at the one end of the cuvette and are joined to top and bottom optical surface areas (48, 50), respectively. 3. The cuvette of claim 2, further characterized by: an end optical surface area (49) formed across the remaining end of the cuvette, the end optical surface area including inner and outer planar surfaces; the planar surfaces of the top and bottom optical surface areas (48, 50) being perpendicular to the planar surfaces of the end optical surface area (49). 4. The cuvette of claims 1-3, wherein the optical surface areas (48-50) are further characterized by being recessed inwardly from the adjacent edges of the side walls (45) to protect the optical surface areas (48-50) from abrasion or physical contact. 5. The cuvette of claims 1-4, wherein the optical surface areas (48-50) are further characterized by inner and outer planar surfaces that are parallel to one another. 6. The cuvette of claims 1-5, wherein the end wall at the remaining end of the cuvette (10) is further characterized by a transverse protruding ledge (68) flush with the adjacent end edges of the side walls (45). 7. The cuvette of claims 1-6, further characterized by the opening (52) extending completely across the one end of the cuvette (10). 8. The cuvette of claims 1-7, further characterized by: a detent (51) formed along the bottom wall (47) of the cuvette (10). 9. In combination with a plurality of the cuvettes of claims 1-8, a cuvette package that facilitates storage, handling and insertion of stacked cuvettes (10) for use in a chemical analyzer, the cuvette package being further characterized by: an elongated cartridge (40) formed from a C-shaped channel (41) encircling a plurality of the cuvettes (10) while transversely stacked in identical abutting parallel positions within the cartridge (40); first stop means (42) within the cartridge for limiting motion of a stack of cuvettes (10) in a first direction along the length of the cartridge (40); and second stop means (43) within the cartridge (40) for resisting motion of the stack of cuvettes (10) in an opposite direction along the length of the cartridge (40). 10. The combination of claim 9 wherein the cartridge (40) is additionally characterized by being double-ended and holds two stacks of cuvettes (10) that face oppositely at its respective ends; the first stop means (42) being located near the center of the cartridge (40); the second stop means (43) being located adjacent each end of the cartridge (40).

Inventors: KELLN NORMAN, OLSON ROBIN, TIFFANY THOMAS, WEYRAUCH BRUCE, KELLN, NORMAN, OLSON, ROBIN, TIFFANY, THOMAS, WEYRAUCH, BRUCE
Applicants: KELLN NORMAN, OLSON ROBIN, SCHIAPPARELLI BIOSYSTEMS INC, SPECTRUM SYSTEMS INC, TIFFANY THOMAS, WEYRAUCH BRUCE, SCHIAPPARELLI BIOSYSTEMS, INC., SPECTRUM SYSTEMS, INC.
Application year: 1993
Main classification: G01N21
IPC codes: B01L3, G01N21, G01N35