TECHNICAL FIELD

The present disclosure relates to a test system for analyzing a sample of a bodily fluid, a method for controlling a transport of a sample of bodily fluid within a test strip and a method for analyzing a sample of a bodily fluid. The device and methods according to the present disclosure specifically may be used to control a transport of a sample of bodily fluid within a test strip. In particular, the device and the method may be applied in the field of qualitatively and/or quantitatively detecting one or more analytes such as glucose, lactate, triglycerides, cholesterol or other analytes, typically metabolites, in one or more body fluids such as blood, typically whole blood, plasma, serum, urine, saliva, interstitial fluid or other body fluids, both in the field of professional diagnostics and in the field of home monitoring. However, other fields of application are feasible.

BACKGROUND

In the field of medical technology and diagnostics a large number of devices and methods for detecting at least one analyte in a bodily fluid are known. The devices and methods may be used for detecting at least one analyte present in one or both of a body tissue or a body fluid, in particular one or more analytes such as glucose, lactate, triglycerides, cholesterol or other analytes, typically metabolites, in bodily fluids such as blood, typically whole blood, plasma, serum, urine, saliva, interstitial fluid or other body fluids. Further devices are known for measuring activating times, e.g., a thrombin activation time measurement for coagulation monitoring.

The detection of at least one analyte present in one or both of a body tissue or a bodily fluid as well as corresponding medication is an essential part of daily routine for many patients. In order to increase convenience and in order to avoid restricting the daily routine by more than a tolerable degree, many test devices and test elements are known in the art and commercially available.

A large number of test devices and test systems are known which are based on the use of test elements in the form of test strips, in particular capillary test strips. Therein, capillary test strips usually comprise an inlet opening configured to receive an amount of bodily fluid and a vent opening configured to provide an air vent to the capillary channel.

Further, in many cases, the test strips comprise one or more test fields having one or more test chemistries or test chemicals. The test chemicals are typically adapted to change one or more detectable properties in the presence of the at least one analyte to be detected. Thus, electrochemically detectable properties of the test chemistry and/or optically detectable properties of the test chemistry may be changed due to the influence of the presence of the analyte. For potential test chemicals, also referred to as test chemistries, which may be used within the present disclosure, reference may be made to J. Hönes et al.: Diabetes Technology and Therapeutics, Vol. 10, Supplement 1, 2008, S-10 to S-26. However, other types of test chemistries may be used within the present disclosure.

In some embodiments, the detection of the at least one analyte can be performed by using an electrochemical test element. Such test elements typically comprise at least one working electrode for detecting the analyte as well as at least one counter electrode to support a current flow through a measuring cell of the test element. In addition, optionally, the test element may comprise at least one reference electrode. Additionally, or alternatively, at least one reference electrode may be combined with at least one counter electrode. However, other types of measurement setups are possible, in order to derive an analyte concentration from a comparison of electrode potentials. The test strips are typically connected with a related instrument before the sample is dosed to the strip to allow a controlled and defined measurement sequence.

For certain capillary test strip concepts, the sample has to be transported over long distances within the capillary channel from the inlet opening to a zone where the optical and/or electrical detection occurs. Often, blood samples show high viscosities especially in case of high hematocrit levels or at low temperatures. As a result, several actions have to be taken to provide a reliable and reproducible sample transport by just capillary forces. First, a preparation of the capillary walls with detergents is advantageous to provide a very good wettability of the capillary walls suitable for a wide range of sample material properties as well as to enable a regulation of a flow of the sample in the capillary channel. However, the usage of detergents also entails the risk that these detergents interfere with the detection chemistry and thereby have an effect on the analysis result. Second, the size of the cross section in most cases has to be adapted to the amount and dimensions of erythrocytes to provide a sufficient transport of blood samples even with high hematocrit levels. However, this requirement typically leads to the necessity of higher sample volumes. Third, a maximum length of a capillary has to be considered in order to provide a filling just by capillary forces. However, this typically leads to an exclusion of otherwise preferred test strip concepts.

In summary, passive sample transport by capillary forces is limited through several disadvantages and/or technical challenges. To overcome the above mentioned drawbacks, an active triggering and/or regulation of the sample transport within the capillary channel is therefore desirable.

Active transport elements can be implemented within a test element. However, if active transport elements are implemented within a disposable test element, especially within a test strip, the production process typically becomes significantly more complex compared to simple reel to reel produced test strips made from foils. Consequently, in many cases, production costs and prices for the test elements increase significantly.

In US 2012/0178179 A1 a diagnostic cartridge and a control method for the diagnostic cartridge are disclosed. The cartridge includes a sample port through which a sample is injected, a first chamber moving the sample injected from the sample port, a second chamber moving a substrate solution, a first membrane formed at a distal end of the first chamber to function as a valve for preventing other substances from being injected into the first chamber after the sample is completely moved, and a second membrane formed at a distal end of the second chamber to function as a valve for preventing other substances from being injected into the first chamber after the substrate solution is completely moved.

Still, the cartridge disclosed by US 2012/0178179 A1 is highly complex and requires a sophisticated channel structure. Further, fluid control of liquids within the cartridge is fully performed by using external pumps, which implies the technical challenge of positioning the liquids in certain positions. Thus, once a pressure or a vacuum is applied to a suction opening of the cartridge, the pressure or vacuum spreads through the complex channel structure of the cartridge, and the liquids are moved accordingly. However, the movement or the stopping of a movement occurs in a highly uncontrollable and delayed fashion, which typically renders a precise positioning of the liquids nearly impossible. A precise positioning, however, including a controlled transport and a controlled standstill of liquids, is highly desirable for performing analytical measurements, specifically in case very small volumes of liquids are used, such as volumes of less than 1 μL or even less than 500 nL.

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 a test system for analyzing a sample of a bodily fluid, a method for controlling a transport of a sample of bodily fluid within a test strip, and a method for analyzing a sample of bodily fluid.

Although the embodiments of the present disclosure are not limited to specific advantages or functionality, it is noted that means and methods are disclosed herein, which are applicable for analysis of very small amounts of liquid samples and which, still, allow for a precise positioning and a precisely controlled transport of the small amounts of liquid.

In accordance with one embodiment of the present disclosure, a test system for analyzing a sample of a bodily fluid is provided comprising: at least one test strip comprising at least one capillary channel, the capillary channel comprising an inlet opening configured to receive the sample of the bodily fluid; a vent opening configured to provide an air vent to the capillary channel; and at least one zone selected from the group consisting of a detection zone and a reagent zone; at least one measuring device configured for interacting with the test strip, the measuring device comprising at least one sealing element configured for hermetically sealing the vent opening of the test strip from an ambient atmosphere; and at least one suction device adapted to provide an underpressure to the vent opening; wherein the measuring device further comprises at least one valve or is connectable to the at least one valve.

In accordance with another embodiment of the present disclosure, a method for controlling a transport of a sample of bodily fluid within a test strip is provided, the method comprising using a test system as recited above, the method comprising the following steps: connecting the test strip to the measuring device; connecting the vent opening to an ambient atmosphere; applying the sample of bodily fluid to the inlet opening of the capillary channel; generating an initial flow of the sample of the bodily fluid by capillary force; and generating an underpressure in the capillary channel and achieving a subsequent flow of the sample of the bodily fluid, thereby transporting the sample of bodily fluid to the at least one zone selected from the group consisting of a detection zone and a reagent zone.

In accordance with yet another embodiment of the present disclosure, a method for analyzing a sample of a bodily fluid is provided, the method comprising transporting the sample of the bodily fluid by using the method recited above, wherein the method further comprises conducting an analysis of the sample of the bodily fluid by using the test strip and at least one analysis device of the measuring device.

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.

