Modular wash bridge for multi-channel immunoassay systemsCROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. provisional application serial No. 62/529,595 filed on 7/2017, which is incorporated herein by reference in its entirety.
Technical Field
The present invention relates generally to an automated immunoassay analyzer system for use in a laboratory environment, and more particularly to a system and method for processing and performing tests on patient samples in an immunoassay analyzer for in vitro diagnostics.
Background
In Vitro Diagnostics (IVD) allows laboratories to assist in the diagnosis of disease based on assays performed on patient fluid samples. IVD includes various types of analytical tests and assays related to patient diagnosis and treatment, which may be performed by analyzing a fluid sample taken from a patient's body fluid or abscess. These assays are typically performed using an automated clinical chemistry analyzer (analyzer) to which a fluid container, such as a cuvette containing a patient sample, has been loaded. The analyzer extracts a liquid sample from the tube and mixes with various reactants in a special reaction cuvette or tube (commonly referred to as a reaction vessel or cuvette).
For analyzers, a modular approach is typically used. Some larger systems include laboratory automation systems that shuttle patient samples between one sample processing module and another. These modules include one or more stations, including a sample processing station and a testing station. A test station is a unit that is dedicated to certain types of assays and provides predetermined test services to samples in an analyzer. Exemplary testing stations include an Immunoassay (IA) station and a Clinical Chemistry (CC) station. In some laboratories, typically including smaller laboratories, these test stations may be provided as independent/independently operating analyzers or test modules, allowing an operator to manually load and unload individual samples or sample trays for CC or IA testing at each station in the laboratory.
A typical IA analyzer module is a clinical analyzer (integrated into a larger analyzer or operating independently) that automates heterogeneous immunoassays using magnetic separation and chemiluminescent readout devices. Immunoassays utilize the presence of specific antibodies to the analyte being tested or specific antigens to the antibodies being tested. Such antibodies will bind to the analyte in the patient sample to form an "immune complex". In order to use antibodies in immunoassays, they are modified in a specific way to suit the needs of the assay. In heterogeneous immunoassays, one antibody (capture antibody) is bound to a solid phase (fine suspension of magnetic particles of IA cartridge) to allow separation using a magnetic field, followed by a washing process. This is exemplified in sandwich assays and competitive assays. The exemplary IA module menu may include additional variations on these forms.
In a typical sandwich assay format, two antibodies are used, each antibody being selected to bind to a different binding site on an analyte molecule, which is typically a protein. An antibody is coupled to a magnetic particle. Another antibody was conjugated to an acridinium ester molecule (AE). During the assay, the sample and the two modified antibody reagents were added to the cuvette. If analyte is present in the patient sample, the two modified antibodies will bind and "sandwich" the analyte molecule. Then, a magnetic field is applied, which attracts the magnetic particles to the walls of the cuvette and washes away the excess reactants. The only AE-labeled antibody remaining in the cuvette was the antibody that formed the immune complex by forming a sandwich with the magnetic particle. An acid solution is then added to release the AE into a solution that also includes the hydrogen peroxide required for the chemiluminescent reaction. Then a base is added to decompose it, emitting light (see reaction below-various AEs were used in various assays, but the basic chemistry is essentially the same). Light is emitted in flashes of light lasting a few seconds and is collected and measured in a photometer. The integrated light output is expressed as Relative Light Units (RLU). This is compared to a standard curve generated by fitting a dose-response curve to RLU values generated from known standards of the same analyte over their clinical range. Sandwich assays produce direct dose-response curves, where higher analyte doses correspond to increased RLU.
Competitive assay formats are applicable to molecules that use only one antibody. The antibody is coupled to a magnetic particle. The second assay reactant comprises an analyte molecule conjugated to an AE. During the assay, the amount of reactants is selected such that the analyte from the patient sample and the AE labeled analyte compete for a limited amount of antibody. The more patient analytes, the less AE labeled analytes will bind to the antibody. After magnetic separation and washing, the only source of AE in the cuvette was from AE-labeled analyte that had been bound to the magnetic particles by the antibody. Acid and base were added as before and dose analysis was performed as described for sandwich assays. Competitive assays produce an inverse dose-response curve, with higher signals corresponding to lower amounts of analyte in the patient sample.
The IA analyzer module magnetic particle reactant is also referred to as the "solid phase" and the AE labeled reactant is referred to as the "lite reactant. The IA analyzer module provides hardware and software to enable multiple assays of various formats to be run simultaneously with random access and high throughput.
At the center of a typical IA analyzer/module is an incubation loop. In order to perform the above measurements, the reaction needs to take place within a well-controlled temperature range, which usually coincides with the nominal temperature of the human body. The incubation loop provides a regulated thermal mass to ensure that the cuvette maintains this temperature range as it moves in the IA module. By providing a ring, random access to the cuvette may be provided. This allows assays of different lengths to be performed simultaneously in parallel, allowing some cuvettes to receive analyte/reactant, some cuvettes to receive sample aliquots, some cuvettes to be analyzed, some cuvettes to be washed, etc. The loop is then moved at regular intervals under processor control to ensure that the reaction occurs at a controlled incubation temperature for a prescribed time interval before analysis of the reaction. A typical incubator ring rotates relative to a stationary base, usually driven by a motor fixed to the base, which drives a gear ring or belt on a moving ring.
Figure 1 shows a cross-sectional view of an exemplary prior art incubation ring. The incubation loop 10 comprises two main parts, loops 12 and 14, which generally move together. The inner magnet ring 12 comprises a plurality of arcuate magnets placed at specific locations along the circumference of the ring 12. Moving with the ring 12 is an outer ring 14, the outer ring 14 comprising a plurality of receptacles (called slots, but which may be of any suitable shape) for cuvettes 16. Typically, the rings 12 and 14 are locked together as they move, thereby allowing the cuvette and outer ring 14 to be exposed to the magnetic field for a predetermined amount of time. After a predetermined cycle time, the ring 12 is angularly moved a predetermined amount relative to the ring 14, indexing (index) each cycle such that the cuvettes in the ring 14 are exposed to the magnetic field for a predetermined amount of time, and each cuvette is continuously exposed to the magnetic field. A disadvantage of this configuration is that the scheduling of magnetic field exposure and wash cycles after a predetermined amount of time in the magnetic field can be complex for a large number of samples in the loop 14, especially if the intention is to change the incubation time for these cuvettes, which may be difficult or impossible for such an arrangement.
Incubation temperature control is provided by a stationary heating element 18 placed under the ring 10, which allows a uniform temperature to be applied to the cuvette 16. Certain instruments interact with the cuvettes 16 as they move along the ring 10. The instruments 20 to 24 are circumferentially spaced from each other at predetermined positions. These instruments include a cuvette processor 20 which places a new cuvette into a slot in the ring at a predetermined location. Once each cuvette is placed into the ring, the cuvettes travel with the rotation of the ring until they reach the position of the reagent probe/pipette 22 which places the aspirated portion of the patient sample into the cuvette. After the sample portion is placed in the cuvette, the cuvette travels with the movement of the ring 10 to the location of the reagent pipette 24, and the pipette 24 dispenses the appropriate reagent for a given immunoassay to be performed on a given patient sample. The cuvette then travels with the ring 10, where it is exposed to a magnetic field generated by a magnet in the ring 12, during which the contents of the cuvette are washed by a washing pipette. Typically, the cuvette is exposed to two magnetic field/wash cycles. Finally, the cuvette reaches the position of the elevator 26, and the elevator 26 pushes the cuvette up out of the ring 10 into a position to be read by the photometer 28.
A disadvantage of ring 10 is that the magnets in ring 12 must be curved to match the curvature of ring 12. This can be expensive to manufacture to the tolerances required for medical testing. Furthermore, the flux of the system is largely determined by the radius of the ring 10. For a given size of ring 10, the magnets of ring 12 must be specifically designed for that radius. Often, manufacturers wish to provide different models in product families with different maximum throughputs to cater for customers with different requirements. Because these systems require FDA approval, the radius of each ring 10 in the product family must be independently certified, which can be time consuming and expensive. Thus, a system such as that shown in fig. 1 may not be a flexible design for a product family with different flux requirements for different models. A further disadvantage of this system is that it is only suitable for single step immunoassays. The timing of the wash cycle directly affects the movement of all other cuvettes in the system, thereby complicating scheduling.
Fig. 2 shows another exemplary prior art system 30 in schematic cross-section. Rather than using one loop 10 to hold the cuvettes, such as shown in fig. 1, the system 30 uses two cuvettes to incubate the loops 32 and 34. The rings can be moved independently, providing random access to the contents of each ring. At the same time, an additional ring 36 is placed over the concentric rings 32 and 34. The ring 36 is non-concentric with the rings, allowing the ring 36 to intersect the two rings 34 and 32 on top at different locations along the travel of the rings 32 and 34. The ring 36 is used for a wash cycle, which allows the cuvettes in the ring to be exposed to a magnetic field for a predetermined amount of time and washed independent of the movement of the rings 32 and 34. This allows for a more flexible incubation cycle time for the cuvettes in loops 32 and 34. The piston lifters 40, 42 and 44 are actuators that facilitate the initial movement of the cuvettes from the loop 32 into the wash loop 36, and downward into the loop 34 in the event that an assay requires additional incubation and wash cycles. Once all incubation and washing cycles of the cuvette are completed, the elevator 46 may move the cuvette up into the luminometer 48 to read the assay results.
Fig. 3 shows a top view of the system 30. The rings 32 and 34 are concentric and allow independent cuvette movement. The loop 32 interacts with the instruments 20-24 as discussed. The wash ring 36 is non-concentric, allowing the ring 36 to intersect the rings 32 and 34 at predetermined locations. The elevator is placed at these positions to move the cuvettes up and down into and out of the ring 36 from the rings 32 and 34. An elevator 46 at the luminometer 48 allows the sample to move into the luminometer 48 for testing the results of the immunoassay after the specified incubation and wash times.
While this system provides more scheduling flexibility and a wider variety of immunoassays due to the possibility of using loops 32 and 34 for two-stage assays, system 30 has several drawbacks. First, because the wash ring 36 is a ring, the same problems associated with manufacturing and authenticating bent magnets apply as in ring 10. That is, the ring 36 can be expensive to manufacture, and for the case of all analyzers of the product family, the ring 36 will be limited to a given diameter unless additional certification tests are performed for different diameter wash rings. In addition, multiple elevators add additional expense and scheduling complexity.
Disclosure of Invention
One or more of the shortcomings of the prior art may be addressed by providing a linear bridge wash system that transports cuvettes along a linear track between portions of an incubation loop. This may include transport between parts of the same incubation loop or from one incubation loop to another.
According to one embodiment of the present invention, a linear wash system configured for use in an immunoassay analyzer includes a bridge having a linear track configured to transport a plurality of sample cuvettes, a motorized belt configured to engage and power the plurality of sample cuvettes along the linear track, and one or more wash stations along the linear track. Each washing station comprises: one or more magnets configured to provide a magnetic field across the plurality of sample cuvettes; and a pipette/probe configured to flush the contents of each cuvette while it is in a magnetic field. The linear track has an input configured to receive each cuvette from the first cuvette incubation loop portion and an output configured to deliver each cuvette to the second cuvette incubation loop portion. As used herein, a pipette or probe is an elongated tubular element configured to aspirate and/or dispense a fluid, such as water or a flushing agent.
According to some embodiments, the motorized belt is a serpentine belt made of rubber or similar material or a chain made of rigid material, such as a plastic or metal timing chain, each having a suitable shape to engage the cuvettes for transport along the linear track.
According to some embodiments, the input and output are configured to receive and deliver cuvettes to portions of a single incubation ring. According to one aspect, the linear track may be coplanar with a single incubation ring. According to another aspect, the input and output may be configured to receive a cuvette and deliver the cuvette to portions of two non-concentric incubation rings. In another aspect, the linear track can be coplanar with the two non-concentric incubation rings.
According to some embodiments, the input and output are configured to receive and deliver the cuvettes to portions of two non-concentric incubation loops and a single incubation loop without recalibrating the one or more wash stations.
According to one embodiment of the present invention, an immunoassay analyzer comprises: a cuvette incubation ring having a plurality of grooves on an inner circumference of the incubation ring, each groove configured to hold a sample cuvette and a drive mechanism for rotating the ring; and a plurality of pipettes configured to interact with the cuvettes in the cuvette incubation loop at predetermined locations. The linear wash bridge is configured to receive the cuvettes from the first location of the cuvette incubation loop, wash the contents of each cuvette, and deliver each cuvette to the second location of the cuvette incubation loop. The luminometer is configured to analyze the contents of each cuvette after it has traveled along the linear wash bridge.
According to one aspect, the linear wash bridge can be coplanar with the cuvette incubation loop. In some embodiments, the immunoassay analyzer comprises an actuator configured to push each cuvette from the cuvette incubation ring towards the linear wash bridge at the first position. The actuator may be a pneumatic or hydraulic piston, or an electromechanical element, such as a linear actuator.
In some embodiments, the linear wash bridge comprises a linear track configured to transport the cuvettes, a motorized belt configured to engage and power each cuvette and to provide power along the linear track, and one or more wash stations along the linear track, each wash station comprising one or more magnets configured to provide a magnetic field on each cuvette and a pipette configured to rinse its contents while each cuvette is in the magnetic field.
According to one aspect, the cuvette incubation ring may comprise a heating element mounted in thermal contact with the ring and configured to rotate with the ring. According to another aspect, the linear wash bridge may comprise a plurality of magnets mounted to a linear track, and may be further configured to be placed into another immunoassay having two cuvette incubation loops and to transfer cuvettes from one loop to another loop, wherein such placement is accomplished without reconfiguring the plurality of magnets.
In another embodiment, an immunoassay analyzer comprises a first cuvette incubation loop having a plurality of grooves on an inner circumference, wherein each groove is configured to hold a sample cuvette and a drive mechanism for rotating the first loop, and a second cuvette incubation loop having a plurality of grooves on an outer circumference, wherein each groove is also configured to hold a sample cuvette and a drive mechanism for rotating the second loop. The plurality of pipettes are configured to interact with the cuvettes in the first cuvette incubation loop at a predetermined location. The linear wash bridge is configured to receive the cuvettes from a first location of the first cuvette incubation loop, wash the contents of each cuvette, and deliver each cuvette to a second location of the second cuvette incubation loop. The luminometer is configured to analyze the contents of each cuvette after it has traveled along the linear wash bridge.
Drawings
FIG. 1 is a schematic cross-sectional view of an exemplary prior art incubation ring;
FIG. 2 is a schematic cross-sectional view of an exemplary prior art incubation ring;
FIG. 3 is a schematic top view of an exemplary prior art incubation ring;
fig. 4 is a schematic cross-sectional view of an exemplary single incubation loop system for use with some embodiments;
fig. 5 is a perspective view of an exemplary single incubation loop system for use with some embodiments;
fig. 6 is a cross-sectional schematic of an exemplary dual incubation loop system for use with some embodiments;
fig. 7 is a perspective view of an exemplary dual incubation loop system for use with some embodiments;
FIG. 8 is a perspective view of an exemplary linear wash bridge for use with some embodiments; and
FIG. 9 is a bottom view of an exemplary linear wash bridge for use with some embodiments.
Detailed Description
Embodiments of the immunoassay and incubation/washing systems used therein utilize a linear washing system that acts as a bridge between two points in one or more incubation loops. By utilizing a linear bridge wash system, the bridge can be used with incubation loops of different sizes without the need to redesign and re-certify wash components between models within a product family, as this is a problem in some prior art systems. Furthermore, linear components (such as linear magnets) can be less expensive to manufacture and design than the arcuate magnets used in conventional ring-based washing systems. This may result in an overall reduction in design manufacturing, manufacturing and certification costs for product families utilizing linear bridge washing systems.
Embodiments generally fall into two types of configurations. In a first configuration, a single incubation loop may be used. The ring has a groove along the inner circumference of the ring. These slots open towards the center of the ring. The linear bridge is placed as a chord between two locations in the ring. The chord is preferably a radial chord (e.g., coextensive with the ring diameter) passing through the center of the ring. When each cuvette channel is rotated to a position where the bridge intersects the ring, the cuvettes in that channel can be pushed out of the channel into the bridge towards the center of the ring. A conveyor system within the wash bridge then transports the cuvettes through two wash stations. Each wash station has one or more magnets to provide a magnetic field and a probe (e.g., pipette or nozzle) for rinsing the contents of the cuvette while it is exposed to the magnetic field. After being washed by two wash stations on the linear bridge, each cuvette is moved by the conveyor system of the linear bridge into a trough in the ring on the output side of the bridge. In embodiments where the bridge spans the center point of the ring, the input and output junctions are both located at directly opposite sides of the ring. (Note that the input and output slots will move during the wash cycle, so the input and output slots can have any angular relationship depending on how the rings move during the wash cycle). The washed cuvette can then be lifted to the photometer in different positions while the ring is rotated. Thus, the wash and photometric reading test results can be timed independently.
Another embodiment utilizes two non-concentric incubation loops, one inside the other. By using non-concentric rings, the wash bridge may be placed between the inner circumference of the larger ring and the outer circumference of the smaller ring. The outer ring has a groove configured to hold cuvettes disposed along the inner circumference. The inner ring has a groove configured to hold cuvettes disposed along an outer circumference of the ring. The wash bridge can transport the cuvettes from the inner circumference of the larger ring to the outer circumference of the inner ring. This allows more wells to be used for cuvette incubation than a single loop can provide. This can increase the throughput of the system without changing the wash bridge between the embodiment with one loop and the embodiment with two loops. Thus, the same washing bridge can be used for both the monocyclic and bicyclic embodiments. Furthermore, in the multiple ring embodiment, the diameter of the two rings can be chosen to be any size, as long as the arrangement of the outer edge of the inner ring and the inner edge of the outer ring is the same distance as the length of the wash bridge. In yet another embodiment, space efficiency is low. Instead of using an inner ring and an outer ring, two non-concentric rings may be placed adjacent to each other; a trough is placed on the outside of each ring with a wash bridge between the rings. This may allow the rings to be of the same size or the rings to be of any desired size relative to each other.
FIG. 4 shows a cross-sectional view of an exemplary embodiment of a single loop system 50 using a linear wash bridge 60. The system 50 includes a single incubation ring 52 that includes a plurality of circumferential grooves having openings toward the center of the ring. The cuvettes 54 are placed into these wells by the cuvette loader 20 and filled using the sample probes 22 and the reactant probes 24. Rotation of the ring 52 is in accordance with a prescribed movement program that provides random access to the cuvette while exposing the cuvette to a predetermined incubation cycle. In this embodiment, a ring mounted heating element 56 is placed in thermal contact with the surface of the ring 52. The heating element 56 provides controlled thermal regulation to incubate the cuvette at a specified temperature (such as 37 ℃). Power and control of the heating element 56 may be provided by one or more slip rings 58. The slip ring 58 may be part of a larger static element that provides axial restraint to the rotation of the ring 52. Additional information regarding the operation of the heating element 56 and the slip ring 58 can be found in U.S. patent application No. 62/472,472 entitled "System and Method for Thermal Control of gathering System in Diagnostic Analyzer," filed on 3, 16.2017, which is incorporated herein by reference in its entirety. In some embodiments, a static heating element that does not rotate with the incubation ring may be used.
When the cuvettes are rotated to a predetermined position corresponding to the input side of the wash bridge 60, a pushing element (e.g., a pneumatic/hydraulic piston, linear actuator, lead screw/rack and pinion device) such as a pusher 62 provides a radial force on the cuvettes to push the cuvettes out of the slots in the ring 52 and into the transport mechanism of the wash bridge 60. The wash bridge 60 then transports the cuvettes linearly through a plurality of wash stations that include one or more linear magnets and probes that wash their contents using aspirating and dispensing detergent while the cuvettes are exposed to the magnetic field of the magnets. After the washing step is complete, the cuvettes are delivered by a motion system that provides linear motive force on each cuvette, across a linear bridge, to a slot on the other side of the ring 52. The ring 52 is then rotated with the cuvette in the new well until the cuvette reaches a lift 64 (e.g., a pneumatic/hydraulic piston, linear actuator, lead screw/rack and pinion arrangement) which lifts the cuvette into a luminometer 66 for detection of photometric readings of the results of the immunoassay. Rotational power may be provided to move the incubation loops by motor 68 via a timing belt/chain or direct/gear drive. This allows the ring 52 to rotate under computer control.
Fig. 5 is a perspective view of an exemplary embodiment 50. The incubation ring 52 includes a plurality of grooves 53, the grooves 53 configured to hold cuvettes on the inner circumference. When each well is aligned with the opening for the wash bridge 60, the pusher pushes the cuvette into the motion system of the wash bridge 60, where the wash station performs the wash step. After passing through the wash station, the motion system of the wash bridge 60 places the cuvettes into open slots on opposite sides of the ring 52. This transfer may utilize another pusher device to place the cuvettes into the receiving output wells of the incubation loop.
Fig. 6 is a cross-sectional view of a system 70 in which two incubation loops connected by a wash bridge are used. The incubation loop 52a is a larger diameter incubation loop having the same configuration as the incubation loop 52 in fig. 4. For visual clarity, the static slip ring is not shown. As previously discussed, the incubation loop 52 is thermally regulated by the heating element 56. In this embodiment, the wash bridge 60 extends between the inner circumference of loop 52a and the outer circumference of the smaller incubator loop 72. This allows a greater number of wells in both rings to be used for cuvettes. The ring 72 is also thermally regulated by a heating element (not shown). The cuvette slot is circumferentially placed around the ring 72 and is oriented outwardly, thereby allowing the slot to be exposed to the bridge 60. The incubated cuvette is pushed from the ring 52a towards the washing bridge 60 by the piston 62. The cuvettes exit the wash bridge 60 via the movement mechanism of the wash bridge 60 into open slots in the ring 72. Upon reaching a position 72 coincident with the elevator 64, each cuvette is raised into the luminometer 66 to read the assay results.
Fig. 7 is a perspective view of a double ring system 70. The outer ring 52a is thermally regulated and includes a plurality of inwardly facing slots 53a, the slots 53a being configured to hold cuvettes. When each of these grooves 53a reaches a position coinciding with the entrance of the bridge 60, the cuvette is moved out of the groove of the ring 52a into the movement system of the bridge 60 for washing. After washing is completed by the wash station on the wash bridge 60, the linear motion system positions the cuvettes into corresponding open slots on the inner ring 72. The ring 72 has a plurality of outwardly facing grooves 73 configured to receive and hold cuvettes until the luminometer 66 fig. 5) can be used to read the results of the immunoassay. A lifter (not shown) raises the cuvette upward for reading.
Fig. 8 is an isometric view of a wash bridge 60. Fig. 9 is a bottom view of scrubbing bridge 60. The wash bridge 60 includes a linear wash bridge track 80, which may be made of a suitable rigid material, such as machine aluminum, hard plastic, or fiber reinforced plastic. This provides a rigid linear constraint that contrasts the motion of the cuvette across the bridge. The cuvettes move along the wash bridge track 80 via a motorized belt, such as a timing belt 86, driven by a stepper motor 84. The term electric belt is used herein as a broad term to describe a flexible belt made of a continuous material, such as a rubber timing belt with or without meshing gear teeth, or a chain made of rigid plastic or metal links. The belt includes features configured to engage the cuvettes, such as high friction surfaces or mechanical elements that secure the cuvettes to the moving belt to move the cuvettes along the direction of travel. The motorized belt provides the motive force to transport the cuvettes along the linear wash bridge track 80 of the wash bridge 60.
In some embodiments, the timing belt 86 is arranged as a serpentine belt driven by the motor 84 and tensioned and positioned by an idler pulley 88. The serpentine band 86 includes a plurality of ribs that engage corresponding structural features on the cuvettes that span the linear wash bridge track 80. The cuvettes are passed to washing stations 90a and 90 b. Each wash station includes a linearly actuated pipette (92 a and 92 b) that is driven up and down by a stepper motor (84). The pressure inside the probe may be driven by suitable means, such as by a pneumatic or hydraulic pump or piston, to provide suction and dispense pressure to suck (sip) and spit out to remove extraneous components of the cuvette's contents during the washing process. Prior to interacting with these pipettes, the cuvette 96 passes over linear magnets 94a and 94 b. These linear magnets provide a magnetic field that interacts with the magnetic particles in the reaction fluid, pulling the particles against the walls of the cuvette. This prevents those particles from being washed by the pipette during the suck and spit wash process. The remaining particles then glow later during photometric reading. In this embodiment, two wash stations are provided on the linear bridge 60, as is typical for wash processes in the art. This is typical if the wash process at each station is not sufficient to be completed using a single wash cycle. However, it should be understood that some embodiments use a single wash station that provides substantially complete washing of the contents of the contrast cuvette in a single wash operation, and additional wash stations may be provided as part of the bridge 60 if the immunoassay used would benefit from additional wash processes. The number of wash stations used may be selected based on the overall wash efficiency of the station, which may be influenced by such factors as the wash fluid, the pressure/velocity/volume of the wash fluid, the volume of analyte being washed, the magnetic field strength, the required test accuracy, the cycle time, the number of wash cycles performed at the station, etc.
In some embodiments, serpentine bands 86 are not completely planar, as shown in fig. 8 and 9. In contrast, in some embodiments, the serpentine belt 86 may be twisted such that the motor 84 need not be mounted in the same plane as the wash stations 90a and 90b (e.g., the motor may be mounted below with the drive shaft lying horizontally). This can be done for more efficient packaging if desired.
Desirably, a single design of wash bridge 60 can be used for both the single incubation loop and the dual incubation loop embodiments. Thus, the wash bridge is designed to receive cuvettes from a slot on a first incubation ring portion (such as on the inward-facing circumference of the first incubation ring) and move those cuvettes with linear power (such as via serpentine belt drive) through a suitable number of magnetic wash stations (such as two) before placing the cuvettes into a slot on a second incubation ring portion (such as on the inward-facing circumference of the same incubation ring or on the outward-facing circumference of the second inner incubation ring). It should be understood that some embodiments of the double ring system may operate in reverse (from smaller rings to larger rings). In some embodiments, the linear wash bridge may be designed and certified to operate bi-directionally. This may require more or larger magnets, but may result in more flexible scheduling options.