Patent Publication Number: US-2021172970-A1

Title: Cartridge assembly tray for immunoassay tests

Description:
This application is a continuation of U.S. application Ser. No. 16/217,730, filed Dec. 12, 2018, which is a continuation of U.S. application Ser. No. 15/475,998, filed Mar. 31, 2017, now U.S. Pat. No. 10,161,945, issued Dec. 25, 2018, which is a continuation of U.S. application Ser. No. 15/089,812, filed Apr. 4, 2016, now U.S. Pat. No. 9,616,427, issued Apr. 11, 2017; which is a continuation of PCT/US2014/059264, filed Oct. 6, 2014; which claims the benefit of U.S. Provisional Application No. 61/887,842, filed Oct. 7, 2013. The contents of the above-identified applications are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a cartridge assembly tray for conducting automated immunoassay tests. The cartridge assembly tray secures test cartridges into an assembly to be inserted to an immunoassay apparatus for conducting the test. 
     BACKGROUND OF THE INVENTION 
     In the development of immunoassay systems, many performance requirements need be met. Assays need be sensitive enough to detect analyte at very low levels in the subpicogram to nanogram per milliliter range. Total assay time needs to be 15 minutes or less in order to provide timely results for patient management in point of care situations, or to meet throughput requirements for batch analyzers. In some cases, analyte panels where multiple assays are simultaneously performed with the same sample are advantageous in order to minimize the turnaround time for results and test costs. All-in-one reagent cartridge and an automatic system conducting an immunoassay test on the cartridge is desired for minimal human input error, cost saving, and prompt results. 
     Since the cartridges are disposable items, it is necessary to replace the cartridge from time to time between the tests. For conventional immunoassay systems, operators of the systems need to manually insert the individual cartridges into the systems. Such a process takes time and is prone to human errors. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a cartridge assembly tray for conducting automated immunoassay tests. The tray comprises a base member, a hinged frame coupled to the base member, and a locking mechanism. The base member includes a plurality of slots within the base member. Each of the plurality of slots is to receive a test cartridge. The hinged frame is capable to rotate to an opened position or a closed position. The hinged frame including a horizontal push bar configured to apply a downward force to test cartridges received in the plurality of slots when the hinged frame is in the closed position. The locking mechanism is configured to lock the hinged frame in the closed position when the hinged frame rotates to the closed position. 
     The present invention is also directed to a method for loading a plurality of test cartridges into a test apparatus. The method comprises obtaining the tray; loading the test cartridges into the slots of the base member, wherein the slots fit the test cartridges to prevent the test cartridges from moving laterally in the slots; rotating the hinged frame of the tray to the closed position, wherein the horizontal push bar applies the downward force to the test cartridges secured in the slots when the hinged frame is in the closed position; locking the hinged frame to the closed position by the locking mechanism of the tray; and inserting the tray into a test apparatus. 
     The present invention is also directed to a method for performing a biochemical test in the test cartridges. The method comprises loading the test cartridges into the test apparatus; opening the cap of each of the test cartridges; lifting the probe from the test cartridge; and dipping the probe into the sample well, the reagent wells, the wash wells and the measurement well of the individual test cartridge in a predetermined sequence. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example of a cartridge tray in a closed position to be used in a biochemical test. 
         FIG. 2  illustrates an example of a cartridge tray in an opened position to be used in a biochemical test. 
         FIG. 3  illustrates an example of a test cartridge that can be inserted into a cartridge tray. 
         FIG. 4  illustrates an example of a probe well and a cap of a test cartridge. 
         FIG. 5  illustrates an example of a portion of a cartridge tray and a test cartridge. 
         FIG. 6  illustrates an example of a test cartridge secured in a cartridge tray. 
         FIG. 7  illustrates an example of a test cartridge in a cartridge tray with cap closed. 
         FIG. 8  illustrates an example of a cartridge tray holding multiple test cartridges. 
         FIG. 9  illustrates an example of a cartridge tray that accommodates a cartridge holder carrying one or more test cartridges. 
         FIG. 10  illustrates an example of a cartridge holder can be loaded into a cartridge tray. 
         FIG. 11  illustrates an example of a test cartridge can be loaded into a cartridge holder. 
         FIG. 12  illustrates an example of a test cartridge with its cap opened. 
         FIG. 13  illustrates an example of a test cartridge loaded into the cartridge holder. 
         FIG. 14  illustrates an example of a test cartridge in a cartridge holder with its cap opened. 
         FIG. 15A  illustrates a cartridge holder that holds multiple test cartridges with caps closed. 
         FIG. 15B  illustrates a cartridge holder that holds multiple test cartridges with caps opened. 
         FIG. 16  illustrates an example of a cartridge tray that can accommodate a cartridge holder. 
         FIG. 17  illustrates an example of a cartridge holder secured in a cartridge tray. 
         FIG. 18  illustrates an example of a cartridge tray securing a cartridge holder, where the cartridge holder holds a test cartridge with its cap opened. 
         FIG. 19  illustrates an example of a cartridge tray securing a cartridge holder, where the cartridge holder holds a test cartridge with its cap closed. 
         FIG. 20  illustrates an example of a cartridge tray securing a cartridge holder, where the cartridge holder holds multiple test cartridges with their caps opened. 
         FIG. 21  illustrates an example of a cartridge tray securing a cartridge holder, where the cartridge holder holds multiple test cartridges with their caps closed. 
         FIG. 22  illustrates an example of a process using a cartridge tray to perform a biochemical test, such as an immunoassay test 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Definitions 
     Terms used in the claims and specification are to be construed in accordance with their usual meaning as understood by one skilled in the art except and as defined as set forth below. 
     “About,” as used herein, refers to within ±10% of the recited value. 
     An “analyte-binding” molecule, as used herein, refers to any molecule capable of participating in a specific binding reaction with an analyte molecule. Examples include but are not limited to, (i) antigen molecules, for use in detecting the presence of antibodies specific against that antigen; (ii) antibody molecules, for use in detecting the presence of antigens; (iii) protein molecules, for use in detecting the presence of a binding partner for that protein; (iv) ligands, for use in detecting the presence of a binding partner; or (v) single stranded nucleic acid molecules, for detecting the presence of nucleic acid binding molecules. 
     A “binding pair,” as used herein, refers to two molecules that are attracted to each other and specifically bind to each other. Examples of binding pairs include, but not limited to, an antigen and an antibody against the antigen, a ligand and its receptor, complementary strands of nucleic acids, biotin and avidin, biotin and streptavidin, lectin and carbohydrates. Preferred binding pairs are biotin and streptavidin, biotin and avidin, fluorescein and anti-fluorescein, digioxigenin/anti-digioxigenin. Biotin and avidin, including biotin derivatives and avidin derivatives such as streptavidin, may be used as intermediate binding substances in assay protocols employing complex binding sequences. For example, antibodies may be labeled with biotin (“biotinylated”) and used to bind to a target substance previously immobilized on a solid phase surface. Fluorescent compositions according to the present invention employing an avidin or streptavidin may then be used to introduce the fluorescent label. 
     “Immobilized,” as used herein, refers to reagents being fixed to a solid surface. When a reagent is immobilized to a solid surface, it is either be non-covalently bound or covalently bound to the surface. 
     A “probe,” as used herein, refers to a substrate coated with analyte-binding molecules at the sensing (detecting) side. A probe has a bottom tip. The bottom tip has a sensing surface coated with analyte-binding molecules. 
     Cartridge Tray 
     Referring now to the drawings, and particularly to  FIG. 1 , there is shown a cartridge tray of the present invention, which generally can carry one or more test cartridges. The cartridge tray can carry preferably 2˜16 test cartridges, more preferably 4˜10 cartridges. During operation of a test apparatus, the test apparatus moves the cartridge tray  100  into the apparatus to position the cartridge tray  100  as necessary for the apparatus to drop test probe at precise locations in the wells of the test cartridges secured in the cartridge tray  100 . In the embodiment shown in  FIG. 1 , the cartridge tray  100  includes a base member  110 , a hinged frame  120  and a locking mechanism  130 . 
     The base member  110  includes a plurality of slots  112  within the base member  129 . Each of the plurality of slots  112  is to receive a test cartridge  180 . As shown in  FIG. 1 , each of the plurality of slots  112  has a top opening for receiving a test cartridge  180 . The slot  112  has a size (e.g., length and width) to fit a test cartridge  180  and to prevent the test cartridge  180  from moving laterally in the slot  112 . The slots  112  can have shapes consistent with the outer shapes of the test cartridge  180 . For instance, each of the plurality of slots  112  can have a substantially rectangular shape for receiving a test cartridge  180 , while the test cartridge  180  has a substantially rectangular outer shape. Each of the slots  112  has at least one opening at the bottoms of the slots  112  such that optical signals from the test cartridge  100  is capable to be collected from bottoms of the slots  112 . In some embodiments, the bottoms of the slots  112  are not covered so that the tray  100  can have less weight. 
     The base member  110  can have outside surfaces that include grooves adapted to guide the tray into a tray drive of a test apparatus. In other words, the base member includes the grooves on both sides of the base member. The sides are defined as the side surfaces that are parallel to the axis of the slots of the base member  110 . For instance, the grooves can be arranged in parallel with an axis of the tray  100 . The grooves guide the tray  100  into a test apparatus when a user inserts the tray  100  into the test apparatus. The cartridge tray  100  can further include a handle  114  attached to the base member  110  such that a test apparatus can grip the handle  114  and move the tray  100  into a tray drive of the test apparatus. Alternatively, the handle  114  can be used by a user to push the tray  100  into a test apparatus. 
     The hinged frame  120  is coupled to the base member  110  via one or more hinge  124 . For instance, the hinge  124  can be a bearing that connects the base member  110  and the hinged frame  120 , allowing only a limited angle of rotation between the base member  110  and the hinged frame  120 . The hinge can be a barrel hinge, a pivot hinge, a butt hinge, a case hinge, a piano hinge, a concealed hinge, a butterfly hinge, a flag hinge, a strap hinge, or other types of hinges as understood by a person having ordinary skill in the art. 
     The hinged frame  120  is capable to rotate to an opened position or a closed position. For instance,  FIGS. 1 and 2  illustrate a hinged frame  120  being rotated to the closed position and the opened position, respectively. The hinged frame includes a horizontal push bar  122  configured to apply a downward force to test cartridges  180  received in the plurality of slots  112  when the hinged frame  120  is in the closed position. A combination of the slots  112  and the horizontal push bar  122  secures the test cartridges in the tray when the hinged frame  120  is in the closed position. In some embodiments, the slots  112  and the horizontal bar  122  secure test cartridges  180  such that a robotic arm of the immunoassay test apparatus is capable to open caps of the test cartridges  112  secured on the tray without any movement of the test cartridges  112  relative to the tray  100  and pick up a probe from a test cartridge  180  to perform a biochemical test. 
     The push bar  122  helps preventing lateral movement of the cartridges in the tray. In some embodiments, after the loaded tray is inserted into a test apparatus, the test apparatus shakes the tray before conducting test. The push helps to fix the cartridges in the tray, to prevent lateral movement and accelerating movement of the cartridges relative to the tray. 
     The locking mechanism  130  is to lock the hinged frame  120  in the closed position when the hinged frame  120  rotates to the closed position. In an embodiment illustrated in  FIG. 1 , the lock mechanism  130  includes a spring-loaded pin  132  to reversibly lock the hinged frame  130  in the closed position when the hinged frame  130  rotates to the closed position. The lock mechanism  130  can further include two such spring-loaded pins  132  to lock both left and right side of the hinged frame  130 . As illustrated in  FIG. 1 , the outward ends of the spring-loaded pins  132  can have tilted slope surface so that the hinged frame  120  can be rotated into the closed position passing the tilted slope surface. When the hinged frame  120  contacts the tilted slope surface, the spring-loaded pins  132  retract. After the hinged frame  120  reaching the closed position, the spring-loaded pins  132  return to the extruded positions to lock the hinged frame  120  in the closed position. 
     The cartridge tray  100  can further include a release mechanism  140  to unlock the hinged frame  120  from the closed position. For instance, as shown in  FIG. 1 , the release mechanism  140  can include two tabs for releasing the test cartridges  180  from the slots  112  by a finger motion. The release mechanism  140  can unlock the hinged frame from the closed position by applying a force to the tabs  140  to retract the spring-loaded pin  132  so that the test cartridges  180  can be disposed of from the plurality of slots  112 . When a user uses fingers to squeeze the tabs  140 , the spring-loaded pins  132  retract, the hinged frame  130  can be freely rotates to the opened position. 
     The cartridge tray  100  can be manufactured such that the center of mass of the tray locates at a geometric center of the tray  100 . This is helpful when the test apparatus need to secure the tray  100  and shake the cartridge  180  in the tray  100 . 
       FIG. 2  illustrates that the hinged frame  120  rotates to an opened position. Without the push bar  122  of the hinged frame  120  pushing the cartridges  180  against the slots  112 , the cartridges  180  can be freely removed from the slots  112  and be replaced or disposed of. 
     Test Cartridge 
       FIG. 3  illustrates an example of a test cartridge of the present invention. One or more test cartridges can be placed in a cartridge tray (e.g. tray  100  in  FIG. 1 ) as an assembly ready for automated biochemical tests. In one embodiment ( FIG. 3 ), cartridge  300  comprises a probe well  301  and a protective cap  302  to accommodate and secure the probe. The probe well  301  serves as a protective container for the probe. In one embodiment, the cap  302  is mechanically coupled to the probe well  301  via a hinge  303 . After the probe is inserted in the probe well  301 , the cap  302  is folded over the probe well  301  to fully enclose the probe. The probe may be vertically stored inside the probe well  301  when the protective cap  302  is in a closed position. 
     The cartridge  300  can include lips  340  to be inserted into cavities (not shown) on the side walls of the cartridge tray  100  to further secure the cartridge  300  in the slots  112  of the tray  100 . 
     The cartridge  300  further includes a recess portion  350  for receiving a horizontal push bar (e.g. push bar  122  in  FIG. 1 ). The recess portion may have a bottom surface and two side surfaces to confine a section of the push bar in the space within the recess portion  350 . In other words, the horizontal push bar is bound by a bottom surface and two side surfaces of the recess portion  350  of the test cartridge when the hinged frame  120  is in the closed position. 
     The test cartridge  300  may further comprises a flange  360  that is wider than the wells below. The flange  360  is designed for the cartridge  300  to sit on top of one of the slots  112  when the test cartridge  300  is received in the slot  112 . As illustrated in  FIG. 1 , the flange sits against the slot  112  prevent the cartridge  180  from moving downward against the tray  100 , white the push bar  122  prevent the cartridge  180  from moving upward way from the tray  100 . The flange and the horizontal push bar confine the test cartridge  300  such that the test cartridge  300  cannot move vertically relatively to the tray  100  when the hinged frame  120  is in the closed position. 
     The cartridge  300  may comprise two separate compartments of wells. The first compartment comprises a sample well  311 , and one more reagent wells. In an embodiment as illustrated in  FIG. 3 , the first compartment comprises a first reagent well  312  and a second reagent  313 . For example, the biotin reagent in the first reagent well  312  comprises a biotinylated second antibody. The second reagent well  313  contains a labeled streptavidin. The label may be any typical label used in diagnostic kits, such as fluorescent, chemiluminescent, or enzyme labels. For instance, the biotin and streptavidin reagents may be in dry format or in a wet format of about 5 μL liquid. In some other embodiments, the wells  312  and  313  can be used for storing reagents other than the biotin reagent and streptavidin reagent. 
     The second compartment comprises reconstitution wells  322 , wash wells  325 , and a measurement well  329 . These wells may contain fluids such as buffer and diluent. The reconstitution wells  322  contain buffer or diluents to be dispensed into the sample, biotin and streptavidin wells  311 - 313  for reconstituting the dry reagents in the these wells. The liquids in reconstitution wells may be transferred to wells  311 - 313  using pipettes. Each of the wash wells  325  contains a first aqueous solution to wash the probe after binding steps in the sample, biotin, and streptavidin wells  311 - 313 . In some other embodiments, there can be a different arrangement for the reconstitution and wash wells. For instance, in an alternative embodiment, there can be two reconstruction wells and six wash wells. Other numbers of reconstruction wells and wash wells are possible, as readily understood by a person having ordinary skill in the art. For instance, the cartridge can have preferably 2˜6 reconstruction wells, more preferably 2˜4 reconstruction wells. The cartridge can also have preferably 2˜12 wash wells, more preferably 3˜6 wash wells. 
     The measurement well  329  contains a second aqueous solution. In one embodiment, the second aqueous solution is the same as the first aqueous solution. The measurement well  329  has a light transmissive bottom, which may be transparent or translucent. The light transmissive bottom is used for an optical reading during the immunoassay test. The optical signal at the bottom tip of the probe is read through the light transmissive bottom. In one embodiment, a laser beam is projected through the light transmissive bottom to the bottom tip of the probe excite a die of a fluorescent tag; the fluorescent signal is collected through the light transmissive bottom. In some embodiment, the thickness of the light transmissive bottom is less than 1 mm. The first and second compartments are separate by a distance to prevent liquid penetration from wells containing liquids to wells containing dry reagents. 
     The technique of fluorescent signal detection in a measurement well is discussed in details in Patent Application No. 2011/0312105, the content of which is incorporated herein by reference in its entirety. 
     The top opening of the wells is sealed with any suitable materials, e.g., foil or film  309 . The seal is penetrable. The wells may be opened by piercing the seal by a manual or automated device. To achieve better sealing, rims, i.e. small raised lines, are built around the opening of the wells and the edges round the wet and/or dry well areas. 
     In one embodiment, the cartridge is used to conduct an immunoassay test. Using a pipettor dispensing subsystem, about 50 μL of diluent is transferred from reconstitution wells to each of the sample, biotin, and streptavidin wells on the cartridge. An aliquot of about 20 μL of sample is transferred from a sample tube to the sample well by a pipettor. The cap of the probe well is opened and the probe is transferred to the sample well and the bottom tip of the probe is immersed in the liquid sample mixture. The probe incubates with the liquid sample mixture for a period of time. Afterward, the probe is sequentially transferred to one or more (e.g. 2-4) wash wells. Subsequently, the probe is transferred to a biotin reagent well and incubated for a period of time. The probe is sequentially transferred to wash wells. Afterward, the probe is transferred to a streptavidin reagent well and incubated for a period of time. The probe is sequentially transferred to wash wells and lastly transferred to a measurement well. The labeled streptavidin at the bottom tip of the probe is detected through a light transmissive window of the measurement well. 
     A sample well is a well that receives a sample containing an analyte. A sample well can be a blank well, or it can contain detergents, blocking agents and various additives for the immunoassay, either in a dry format or in a wet (liquid) format. In human blood samples, heterophile antibodies (antibodies that bind IgG from other species) and rheumatoid factor are common interfering substances for immunoassays. There are a variety of blocking agents minimizing this form of interference. For examples, blocking agents include IgGs from different species such as murine IgGs, heat aggregated IgG, crosslinked IgG, and commercially available heterophile blockers. The wet format of blocking agents typically contains a small liquid volume (&lt;10 μL, e.g., 5 μL). The dry format of blocking agents includes a lyophilization cake, powder, tablet or other formats typical in diagnostic kits; the dry format is to be reconstituted to a wet format by a reconstitution buffer and/or sample. The sample well serves as a primary reaction chamber for the reaction between the analyte in the sample and the analyte-binding molecules coated on the probe to form an immunocomplex. 
     The cartridge comprises one or multiple reagent wells. The reagent wells contain reagents that react with the immunocomplex and generate a signal for detection. The reagents can be in a wet format or in a dry format. The wet format contains a reagent in an assay buffer. The wet format is typically in a small liquid volume (&lt;10 μL, e.g., 5 μL). An assay buffer typically includes a buffer (e.g., phosphate, tris), a carrier protein (e.g., bovine serum albumin, porcine serum albumin, and human serum albumin, 0.1-50 mg/mL), a salt (e.g., saline), and a detergent (e.g., Tween, Triton). An example of an assay buffer is phosphate buffered saline, pH 7.4, 5 mg/ml bovine serum albumin, 0.05% Tween 20. The assay buffer optionally contains a blocking agent in an amount of 1-500 μg/mL. The final formulation will vary depending on the requirements of each analyte assay. The dry format is the dry form of the reagent in an assay buffer. The dry format includes lyophilization cake, powder, tablet or other formats typical in diagnostic kits. The dry format is to be reconstituted to a wet format by a reconstitution buffer. 
     In one embodiment, the cartridge contains two or more reagent wells. For example, a first reagent well contains second antibody molecules conjugated with a first member of a binding pair, and a second reagent well contains a second member of the binding pair labeled with reporters. For example, the first reagent well is a biotin reagent well containing a biotinylated second antibody directed against the analyte. The second reagent well is a streptavidin reagent well containing streptavidin labeled with reporters to amplify signal. The reporters can be any of those typically used in diagnostic kits, i.e. fluorescent, chemiluminescent, or enzyme labels. 
     The cartridge comprises one or more washing wells each containing an aqueous solution. The wash wells contain a wash buffer to wash the probe after binding steps in the sample well and reagent well(s). One to four wash wells (e.g., 1, 2, 3, or 4 wells) are dedicated for washing after each binding step. Wash buffers contain detergents. Any detergent typically used in immunoassays (e.g., Tween, Triton) can be used in this invention. 
     The cartridge comprises a measurement well having an optically clear bottom that enables the detection of the labeled-immunocomplex bound to the bottom tip of the probe. The measurement is through the bottom of the well. The measurement well contains a liquid solution. In the case when the label is an enzyme, the aqueous solution contains a substrate of the enzyme. 
     In one embodiment, some of the wash wells are served for the purpose of reconstituting the dry forms in the sample well and reagent well(s). In this case, no additional reconstruction wells are needed. 
     In another embodiment, the cartridge further comprises reconstitution wells that contain reconstitution buffer to be dispensed into the sample wells and reagent wells to reconstitute the dry forms in the sample well and reagent well(s). The reconstitution buffer can be a buffer such as phosphate-buffer saline. The reconstitution buffer can additionally include other additives (carrier protein, blockers, detergents, etc.) contained in the assay buffer. Several configuration of the reconstitution wells are feasible; for example, there can be several wells (50˜200 μL, e.g. 100 μL) each dedicated to each one of the sample and reagents, or there can be a single well with a sufficient volume for all the sample and reagents. 
       FIG. 4  illustrates an example of the probe well  401  and the cap  402  of the cartridge, according to one embodiment of the present invention. The cap  402  is hinged to the probe well  402  via a hinge  403  sot that the cap  402  can rotate to a closed position or an open position. The open position of the cap  402  is shown in the  FIG. 4 . The probe well  401  can have a recess (not shown) inside of the opening of the probe well  401 . A cushion may be placed on the recess  404  to support the probe when the probe is stored vertically. The cap  402  may have a pair of clamping arms  406 ; there are a corresponding pole  408  near the probe well  401 . When the cap  402  is in a closed position, the clamping arms  406  are pushed over the extrusion on the pole  408  so that the cap  401  is locked in the closed position. An ordinary skilled person in the art will readily use other shapes or mechanisms to serve the purpose of the clamping arms. 
     The clamping arms  406  can further include outward extrusions  416 . As illustrated in  FIG. 5 , the cap  402  of the cartridge  180  can be also secured on a tray when the cap  402  is opened. After the push bar is applied to push the cartridge  180  against the slots  112 , the cap  402  can be opened to pass one or more tabs  128  attached to the hinged frame  120  of the tray to secure the cap  402  from reverting back, so that the cap  402  does not accidentally close itself during the biochemical test such as an immunoassay test. A user can pinch the two clamping arms  406  toward each other when the user pushes the cap  402  toward the tabs  128 . Since the two clamping arms  406  are pinched together, the outward extrusions  416  can pass the tabs  128  without being blocked. Once the outward extrusions  416  of the clamping arms  406  pass the tabs  128 , the user releases the fingers from the clamping arms  406 . The clamping arms  406  return to their original positions. The space between the tabs  128  are designed such that the extrusions  416  in the unforced positions cannot pass through the tabs  128 . Therefore, the cap  402  is locked in a position by the tabs  128 . Such a mechanism guarantees that the cap  402  does no accidentally revert back to interfere with the probe conducting the biochemical test in the wells. 
       FIG. 6  illustrates a test cartridge secured in a cartridge tray. Similar to  FIG. 5 , the space between the tabs are designed such that the extrusions in the unforced positions cannot pass through the tabs. The cap is locked in a position by the tabs. After conducting a biochemical test, the test apparatus can release the cap from the locked position by squeezing the outward extrusions  416  of the test cartridge and close the cap.  FIG. 7  illustrates a test cartridge in a cartridge tray with the cap closed.  FIG. 8  illustrates a cartridge tray holding multiple test cartridges. 
     Cartridge Tray with Holder 
       FIGS. 9-21  illustrate another example of cartridge tray of the present invention.  FIG. 9  illustrates a cartridge tray that accommodates a cartridge holder carrying one or more test cartridges. The cartridge holder can carry preferably 2˜16 test cartridges, more preferably 4˜10 cartridges.  FIG. 10  illustrates a cartridge holder can be loaded into a cartridge tray. The cartridge holder  1000  includes a notch  1001  on the bottom. When the cartridge holder  1001  is placed into a cartridge tray, the notch  1001  sites on top of a bar of the cartridge tray such that cartridge holder  1000  cannot move laterally relative to the cartridge tray. The cartridge holder  1000  further includes a plurality of slots  1002  to receive one or more test cartridges. The slots  1002  can have shapes consistent with the outer shapes of the test cartridge. For instance, each of the plurality of slots  1002  can have a substantially rectangular shape for receiving a test cartridge, while the test cartridge has a substantially rectangular outer shape. The cartridge holder  1000  also includes a plurality of holes  1003 . The inner shapes and dimensions of the holes  401  are designed to accommodate the bottom of the probe well  401  of the test cartridge (illustrated in  FIG. 4 ). 
       FIG. 11  illustrates an example of a test cartridge can be loaded into a cartridge holder. The cap of the test cartridge is closed.  FIG. 12  illustrates a test cartridge with its cap opened.  FIG. 13  illustrates a test cartridge loaded into the cartridge holder. Due to the shapes of the slots and holes of the cartridge holder, the test cartridge cannot move laterally relative to the cartridge holder.  FIG. 14  illustrates a test cartridge in a cartridge holder with its cap opened. The cartridge holder can accommodate multiple test cartridges depending on the number of the slots.  FIG. 15A  illustrates a cartridge holder that holds totally  10  test cartridges. Each slot of the cartridge holder holds one of the test cartridges.  FIG. 15B  illustrates a cartridge holder that holds multiple test cartridges with their caps opened. 
     During operation of a test apparatus, the test apparatus moves the cartridge tray into the apparatus to position the cartridge tray as necessary for the apparatus to drop test probe at precise locations in the wells of the test cartridges secured in a holder in the cartridge tray. In the embodiment shown in  FIG. 16 , the cartridge tray  1600  includes a base member  1610 , a hinged frame  1620  and a locking mechanism  1630 . 
     The base member  1610  includes a plurality of slots  1612  within the base member  1610 . The base member  1610  can have outside surfaces that include grooves adapted to guide the tray into a tray drive of a test apparatus. For instance, the grooves can be arranged in parallel with an axis of the tray  1600 . The grooves guide the tray  1600  into a test apparatus when a user inserts the tray  1600  into the test apparatus. The cartridge tray  1600  can further include a handle  1614  attached to the base member  1610  such that a test apparatus can grip the handle  1614  and move the tray  1600  into a tray drive of the test apparatus. Alternatively, the base member  1610  and/or the hinged frame  1620  can include mechanical features (e.g., grooves, notches, bars, tabs, etc.) so that the test apparatus can push or pull the mechanism features to move the tray cartridge. 
     The base member  1610  and/or the hinged frame  1620  can include various mechanical features to help the test apparatus to move the cartridge tray or to secure the position of the cartridge tray. For example, the base member  1610  can include multiple vertical notches on the sides of the base member  1610 , such that the test apparatus can use pins aligned into the grooves to secure the position of the cartridge tray. The directions of the vertical notches are parallel to the direction of the gravity, when the tray is lying horizontally. 
     The hinged frame  1620  is coupled to the base member  1610  via one or more hinge  1624 . The hinged frame  1620  is capable to rotate to an opened position or a closed position. The hinged frame includes a horizontal push bar  1622  configured to apply a downward force to the cartridge holder and test cartridges when the hinged frame  1620  is in the closed position. A combination of the slots  1612  and the horizontal push bar  1622  secures the cartridge holder in the tray when the hinged frame  1620  is in the closed position. 
     The locking mechanism  1630  is to lock the hinged frame  1620  in the closed position when the hinged frame  1620  rotates to the closed position. In an embodiment illustrated in  FIG. 1 , the lock mechanism  130  includes a spring-loaded pin to reversibly lock the hinged frame  1630  in the closed position when the hinged frame  1630  rotates to the closed position. The lock mechanism  1630  can further include two such spring-loaded pins to lock both left and right side of the hinged frame  1630 . The outward ends of the spring-loaded pins can have tilted slope surface so that the hinged frame  1620  can be rotated into the closed position passing the tilted slope surface. When the hinged frame  1620  contacts the tilted slope surface, the spring-loaded pins retract. After the hinged frame  1620  reaching the closed position, the spring-loaded pins return to the extruded positions to lock the hinged frame  1620  in the closed position. 
     The cartridge tray  1600  can further include a release mechanism  1640  to unlock the hinged frame  1620  from the closed position. The release mechanism  1640  can include two tabs for releasing the test cartridges by a finger motion. The release mechanism  1640  can unlock the hinged frame from the closed position by applying a force to the tabs  1640  to retract the spring-loaded pin so that the test cartridges can be disposed. When a user uses fingers to squeeze the tabs  1640 , the spring-loaded pins retract, the hinged frame  1630  can be freely rotates to the opened position. In some embodiments, after the tabs  1640  is squeezed, the spring-loaded pins stay in retracted positions, even that squeezing forces no longer apply to the tabs  1640 . Then the hinged frame can be moved to an opened position without any obstacles. Once the tabs  1640  is squeezed again, the spring-loaded pins move back to the extruded position such that the hinged frame can be locked into the closed position again. 
     The base member  1610  can further include a holder bar  1670  to help secure the position of the cartridge holder. As shown in  FIG. 10 , the cartridge holder includes a notch  1001  at the bottom. The notch  1001  is shaped to accommodate the holder bar  1670 . In other words, at least some surface of a bottom notch of the cartridge holder is contacting the holder bar such that the cartridge holder does not move laterally relative to the base member, when the cartridge holder is reversibly attached to the base member.  FIG. 17  illustrates a cartridge holder secured in a cartridge tray. The cartridge holder cannot move laterally relative to the cartridge tray when the hinged frame is in a closed position, because the bar  1570  is placed in the notch of the cartridge holder. 
     One or more test cartridges can be placed into the cartridge holder. Then the cartridge holder can be placed into the cartridge tray.  FIG. 18  illustrates a cartridge tray securing a cartridge holder, where the cartridge holder holds a test cartridge with its cap opened. The tabs of the cartridge tray helps to secure the cap of the test cartridge in its opened position. After conducting a biochemical test, the test apparatus can release the cap from the locked position by squeezing the outward extrusions of the test cartridge and close the cap.  FIG. 19  illustrates a cartridge tray securing a cartridge holder, where the cartridge holder holds a test cartridge with its cap closed. Similarly,  FIG. 20  illustrates a cartridge tray securing a cartridge holder, where the cartridge holder holds multiple test cartridges with their caps opened.  FIG. 21  illustrates a cartridge tray securing a cartridge holder, where the cartridge holder holds multiple test cartridges with their caps closed. 
     Biochemical Test Using the Cartridge Tray 
       FIG. 22  illustrates a sample process  2200  of using a cartridge tray to perform a biochemical test, such as an immunoassay test. At step  2205  of the process  2200 , the process obtains a cartridge tray such as the tray  100  illustrated in  FIG. 1  or the tray  1600  illustrates in  FIG. 16 . At step  2210 , the process loads one or more test cartridges into the slots of the base member of the cartridge tray. The slots fix the test cartridges from lateral movement in the slots. If a cartridge holder is used (e.g., holder  1000  illustrated in  FIG. 10 ), the process loads the one or more test cartridges into the slots of the cartridge holder. Then the cartridge holder is loaded onto the cartridge tray. 
     The test cartridges can be secured in the tray as an assembly. At step  2215 , the process rotates the hinged frame of the tray to a closed position. At the closed position, the horizontal push bar applies the downward force to the test cartridges to fix the cartridges in the slots. At step  2220 , the process locks the hinged frame to the closed position by a locking mechanism of the tray, such as the spring-loaded pins  132  in  FIG. 1 . At step  2225 , the process inserts the tray into a test apparatus. 
     The test apparatus conduct biochemical tests on the assembly of cartridges secured in the tray. At step  2230 , the test apparatus loads the test cartridges into the test apparatus by, e.g., dragging the tray via the handle  114 . At step  2240 , optionally, the test apparatus pierces each of the covers of the sample well, the reagent wells, the wash wells and the measurement well of the test cartridge secured in the tray. The piecing may be conducted using a dedicated piecing device, using a pipette tip, or using the probe from the cartridge. In some embodiments, the test apparatus can pierce or open the covers of all or some of the test cartridges on the tray at once before conducting the biochemical tests. In some other embodiments, the test apparatus can pierce or open the covers of each test cartridge immediately before conducting the biochemical test on that test cartridge. 
     At step  2245 , the apparatus transfers a test sample to the sample well of the individual test cartridge. At step  2250 , the apparatus opens at least one cap of one of the test cartridges. In some embodiments, the test apparatus can open the caps of all or some of the test cartridges on the tray at once before listing any probe from the test cartridges. In some other embodiments, the test apparatus can open the cap of each test cartridge immediately before lifting a probe of that test cartridge. 
     At step  2255 , the test apparatus lifts a probe from one of the test cartridges. At step  2238 , optionally, the test apparatus shakes the tray. At step  2260 , the test apparatus dips the probe into the sample well, the reagent wells, the wash wells and the measurement well of the individual test cartridge in a predetermined sequence. At step  2265 , optionally the test apparatus stops shaking the tray and collects optical signals from, e.g., bottoms of the slots when optical signals can travel through transparent windows of the cartridges and the bottoms of the slots. 
     After conducting the biochemical tests, the tray can be released from the test apparatus and the cartridges can be removed from the tray. At step  2270 , after the measurement, if the test apparatus has stopped shaking the tray at step  2265 , then it transfers the cartridge out of the test apparatus; otherwise, stop shaking before transferring the cartridge out of the test apparatus. At step  2275 , the process unlocks the hinged frame by applying a force on a release mechanism of the tray. At step  2280 , the process rotates the hinged frame to the opened position. At step  2285 , the process disposes of the test cartridges from the tray. 
     Those skilled in the art will appreciate that the logic illustrated in  FIG. 22  and described above, and in each of the flow diagrams discussed below, may be altered in a variety of ways. For example, the order of the logic may be rearranged, substeps may be performed in parallel, other logic may be included, etc. 
     The invention, and the manner and process of making and using it, are now described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains, to make and use the same. It is to be understood that the foregoing describes preferred embodiments of the present invention and that modifications may be made therein without departing from the scope of the present invention as set forth in the claims. To particularly point out and distinctly claim the subject matter regarded as invention, the following claims conclude this specification.