Test procedures operating with test elements are used on a large scale to analyze the components in a liquid sample qualitatively and quantitatively, particularly in body fluids of humans or animals. These test elements contain reagents. For the execution of a reaction, the test element is brought into contact with the sample. The reaction of sample and reagent leads to a change of the test element which is characteristic for the analysis, and is evaluated by means of an appropriate evaluation instrument. Generally, the evaluation instrument is appropriate for the evaluation of a certain type of test elements of a certain manufacturer. The test elements and the evaluation instrument are components which are mutually adapted to each other and together designated as analysis system.
Numerous test element types are known, which can be differentiated by the measuring principle, the used reagents as well as by their structure.
With respect to the measuring principle, colorimetric analysis systems are used very frequently. Here the reaction of the sample with the reagents contained in the test element leads to a color change which can be measured visually, or by using a photometric measuring device. Furthermore, electrochemical analysis systems have obtained high importance, wherein the reaction of the sample with the reagents of the test elements leads to an electrically measurable change (of an electrical voltage or an electrical current), to be measured by means of corresponding electronic measuring system.
With respect to the structure, strip-shaped analysis elements (test strips) are particularly common, consisting of an elongated carrier layer made of plastic material, and test fields fixed onto this carrier layer. Generally, the test fields consist of test layers which contain one or more reagents. Such test strips are particularly used, to a large extent, for blood and urine investigations.
A second type of test elements, which so far is used only to a small extent in practice, has a test field surrounded by a frame, similar to a photographic diapositive. In the English literature, such test elements are called “analysis slides”. The test field of this test element type generally consists of one or more test layers supported by the frame and containing reagents appropriate for colorimetric tests. After the application of the sample to the test field and the process of the test reaction, a color generation can be observed, or photometrically measured, on the opposite side (generally the underside) of the test field. Such test elements with frames are known, for example, from U.S. Pat. No. 5,173,261.
Furthermore, special forms of test elements have been proposed for special applications. For example, EP 0312394 A2 describes a test element for immunochemical tests, wherein a membrane, containing immunochemical substances, is mounted in a plastic part shaped as a truncated cone. The plastic part is attached to a syringe in order to aspire a liquid through the membrane by means of the syringe plunger, thus enabling the separation of bound and free reagent components which is required in this type of test.
In most cases, test element analyses are performed manually. However, numerous analysis systems have been proposed, wherein the analysis is partially or completely automatic. The evaluation instruments of such systems generally contain the following subunits: a test element storage container, in which a plurality of test elements is stored, a sample application location at which the test element is brought into contact with the sample, a measuring device for measuring the change of a test element which is characteristic for the analysis, the test element being located in a measuring position (which may coincide with or be different from the sample application position), and a transport facility which takes one test element at a time from the test element storage container, transports it to the sample application device, and—if necessary—further transports it, after contacting with the sample, to the measuring position.
Very different proposals have been made with respect to the constructive design. For example, U.S. Pat. Nos. 3,932,133 and 4,876,204 describe evaluation instruments wherein the test element storage container is shaped as a magazine in which a plurality of test strips are stored in a stacked manner, one upon the other. In order to take the test strips out of the container and to transport them to the subsequent processing stations, a transport device with a gripper, taking up one test stripe at a time, is provided.
In GB2014113 A, EP0054849 and U.S. Pat. No. 5,143,694, different developments are described, which have in common that test strips are transported, by means of a transport device, continuously in a direction transversal to their longitudinal direction, passing the necessary processing stations. To this end GB 2014113 uses a cylinder, EP 0054849 uses a continuously transporting paper strip, and U.S. Pat. No. 5,143,694 uses a system of transport fingers, which push the test strips, via rails within a plastic insert, from an application position via a measuring station to a waste deposit.
All these automatically working test element analysis systems need much space. They are constructively expensive and need relatively much electrical energy. Therefore, they are not appropriate for small, portable battery-operated analysis systems, as they are common for the blood sugar home monitoring of diabetics.
In order to allow a simplified handling in the field of blood sugar home monitoring, EP 0823635 proposes a special form of test elements wherein the test field is integrated into the front face of a carrier element which is shaped as a truncated cone or a truncated pyramid. A plurality of test elements is stacked, one upon the other, in a tube-shaped magazine and stored ready for use in such a manner that a correspondingly designed evaluation instrument can be attached to the respective upper test element in the magazine. To this end a projection of the test element latches into a corresponding recess at the head of the evaluation instrument, thus providing a connection between the test element and the evaluation instrument. Subsequently, the test element fixed to the device is brought into contact with a drop of blood, produced, for example, at the finger tip. The sophisticated form of these test elements causes substantial costs. Nevertheless, handling is not substantially simplified as compared to conventional test strips.
EP 0922959 describes an analysis system which comprises a damp-proof storage container for test elements and an evaluation instrument. The evaluation instrument is equipped with two guiding grooves, namely one guiding groove adapted to a corresponding profile of the test elements, and a second guiding groove, acting together with a corresponding guiding element of the storage container. In order to take a test element from the storage container and to place it into the test element holder of the evaluation instrument, both components are joined, resulting in a direct take-over of a test element from the storage container into the instrument. This facilitates the handling. The design, however, is relatively expensive, and the material consumption for the production of the test elements is relatively high. On this basis, the invention addresses the problem to create a test element analysis system wherein a handling improvement, in particular with respect to the removal of the test elements from a storage container and their transport to a sample application position of the evaluation instrument, is achieved with a low expense. The design shall be simple and must be appropriate for small, portable, battery-operated analysis systems.