TECHNICAL FIELD

The present disclosure relates to analytical test devices for biological samples, in particular to the design and use of rotatable cartridges for performing a measurement of a biological sample.

BACKGROUND

Two classes of analysis systems are known in the field of medical analysis: wet analysis systems, and dry-chemical analysis systems. Wet analysis systems, which essentially operate using “wet reagents” (liquid reagents), perform an analysis via a number of required step such as, for example, providing a sample and a reagent into a reagent vessel, mixing the sample and reagent together in the reagent vessel, and measuring and analyzing the mixture for a measurement variable characteristic to provide a desired analytical result (analysis result). Such steps are often performed using technically complex, large, line-operated analysis instruments, which allow manifold movements of participating elements. This class of analysis system is typically used in large medical-analytic laboratories.

On the other hand, dry-chemical analysis systems operate using “dry reagents” which are typically integrated in a test element and implemented as a “test strip”, for example. When these dry-chemical analysis systems are used, the liquid sample dissolves the reagents in the test element, and the reaction of sample and dissolved reagent results in a change of a measurement variable, which can be measured on the test element itself. Above all, optically analyzable (in particular colorimetric) analysis systems are typical in this class, in which the measurement variable is a color change or other optically measurable variable. Electrochemical systems are also typical in this class, in which an electrical measurement variable characteristic for the analysis, in particular an electrical current upon application of a defined voltage, can be measured in a measuring zone of the test element using electrodes provided in the measuring zone.

The analysis instruments of the dry-chemical analysis systems are usually compact, and some of them are portable and battery-operated. The systems are used for decentralized analysis (also called point-of-care testing), for example, at resident physicians, on the wards of the hospitals, and in so-called “home monitoring” during the monitoring of medical-analytic parameters by the patient himself (in particular blood glucose analysis by diabetics or coagulation status by warfarin patients).

In wet analysis systems, the high-performance analysis instruments allow the performance of more complex multistep reaction sequences (“test protocols”). For example, immunochemical analyses often require a multistep reaction sequence, in which a “bound/free separation” (hereafter “b/f separation”), i.e., a separation of a bound phase and a free phase, is necessary. According to one test protocol, for example, the sample can first be brought in contact with a specific binding reagent for the analyte which is immobilized onto a surface. This can be achieved for example by mixing the sample with beads comprising surfaces with such immobilized reagents or transporting the sample over surfaces or through porous matrices wherein the surfaces or the porous matrices comprise coatings of the immobilized reagents. A marking reagent can subsequently be brought in contact with this surface in a similar manner to mark the bound analyte and allow its detection. To achieve a more precise analysis, a subsequent washing step is often performed, in which unbound marking reagent is at least partially removed. Numerous test protocols are known for determining manifold analytes, which differ in manifold ways, but which share the feature that they require complex handling having multiple reaction steps, in particular also a b/f separation possibly being necessary.

Test strips and similar analysis elements normally do not allow controlled multistep reaction sequences. Test elements similar to test strips are known, which allow further functions, such as the separation of red blood cells from whole blood, in addition to supplying reagents in dried form. However, they normally do not allow precise control of the time sequence of individual reaction steps. Wet-chemical laboratory systems offer these capabilities, but are too large, too costly, and too complex to handle for many applications.

To close these gaps, analysis systems have been suggested which operate using test elements which are implemented in such a manner that at least one externally controlled (i.e., using an element outside the test element itself) liquid transport step occurs therein (“controllable test elements”). The external control can be based on the application of pressure differences (overpressure or low-pressure) or on the change of force actions (e.g., change of the action direction of gravity by attitude change of the test element or by acceleration forces). The external control can be performed by centrifugal forces, which act on a rotating test element as a function of the velocity of the rotation.

Analysis systems having controllable test elements are known and typically have a housing, which comprises a dimensionally-stable plastic material, and a sample analysis channel enclosed by the housing, which often comprises a sequence of multiple channel sections and chambers expanded in comparison to the channel sections lying between them. The structure of the sample analysis channel having its channel sections and chambers is defined by profiling of the plastic parts. This profiling is able to be generated by injection molding techniques or hot stamping. Microstructures, which are generated by lithography methods, increasingly being used more recently, however.

Analysis systems having controllable test elements allow the miniaturization of tests which have only been able to be performed using large laboratory systems. In addition, they allow the parallelization of procedures by repeated application of identical structures for the parallel processing of similar analyses from one sample and/or identical analyses from different samples. It is a further advantage that the test elements can typically be produced using established production methods and that they can also be measured and analyzed using known analysis methods. Known methods and products can also be employed in the chemical and biochemical components of such test elements.

In spite of these advantages, there is a further need for improvement. In particular, analysis systems which operate using controllable test elements are still too large. The most compact dimensions possible are of great practical significance for many intended applications.

BRIEF SUMMARY

It is against the above background that the embodiments of the present disclosure provide certain unobvious advantages and advancements over the prior art. In particular, the inventors have recognized a need for improvements in methods for measurement of an analyte with a cartridge.

In accordance with one embodiment of the present disclosure, a method of performing an optical measurement of an analyte in a processed biological sample using a cartridge is provided, wherein the cartridge is operable for being spun around a rotational axis. The cartridge comprises: a support structure comprising a front face; a fluidic structure for processing a biological sample into the processed biological sample, wherein the fluidic structure comprises a sample inlet for receiving the biological sample; and a measurement structure recessed from the front face, wherein the measurement structure comprises a chromatographic membrane, wherein the measurement structure comprises a measurement structure inlet connected to the fluidic structure to receive the processed biological sample, wherein the measurement structure comprises an absorbent structure, wherein the chromatographic membrane extends from the measurement structure inlet to the absorbent structure, wherein the chromatographic membrane comprises a detection zone, wherein the measurement structure comprises an inlet air baffle connected to the front face. The method further comprises: placing the biological sample into the sample inlet; controlling the rotational rate of the cartridge to process the biological sample into the processed biological sample using the fluidic structure; controlling the rotational rate of the cartridge to allow the processed biological sample to flow from the measurement structure inlet to the absorbent structure via the chromatographic membrane, wherein the inlet air baffle reduces the evaporation of the processed biological sample during rotation of the cartridge; and performing the optical measurement of the detection zone with an optical instrument.

In accordance with another embodiment of the present disclosure, a cartridge for an automatic analyzer is provided, wherein the cartridge is operable for being spun around a rotational axis. The cartridge comprises: a support structure, wherein the support structure comprises a front face; a fluidic structure for processing a biological sample into a processed biological sample, wherein the fluidic structure comprises a sample inlet for receiving the biological sample; and a measurement structure recessed from the front face, wherein the measurement structure comprises a chromatographic membrane, wherein the measurement structure comprises a measurement structure inlet connected to the fluidic structure to receive the processed biological sample, wherein the measurement structure comprises an absorbent structure, wherein the chromatographic membrane extends from the measurement structure inlet to the absorbent structure, wherein the measurement structure comprises an inlet air baffle connected to the front face.

In accordance with yet another embodiment of the present disclosure, a medical system is provided, wherein the medical system comprises a cartridge as described herein, wherein the medical system further comprises an automatic analyzer configured for receiving the at least one cartridge, wherein the automatic analyzer comprises a cartridge spinner, an optical instrument, and a controller configured to control the automatic analyzer, wherein the controller is configured for: controlling the rotational rate of the cartridge to process the biological sample into the processed biological sample using the fluidic structure; controlling the rotational rate of the cartridge to allow the processed biological sample to flow across the fluidic membrane from the measurement structure inlet to the absorbent structure via the chromatographic membrane, wherein the inlet air baffle reduces the evaporation of the buffer solution;

and performing the optical measurement of the detection zone with the optical instrument.

These and other features and advantages of the embodiments of the present disclosure will be more fully understood from the following description in combination with the drawings and the accompanying claims. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussion of features and advantages set forth in the present description.

