Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Calorimeter
Reexamination Certificate
2000-05-19
2003-07-15
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Calorimeter
C422S051000, C422S051000, C436S169000
Reexamination Certificate
active
06592815
ABSTRACT:
The invention concerns an analytical test element for the determination of an analyte in a liquid containing a detection element and a channel capable of capillary liquid transport which has a sample application opening at one end of the channel capable of capillary liquid transport. The invention also concerns the use of the said analytical test element for the determination of an analyte in a liquid as well as a method for the determination of an analyte in a liquid sample with the aid of the said analytical test element.
So-called carrier-bound tests are often used for the qualitative or quantitative analytical determination of components of body fluids, in particular of blood. In these the reagents are contained in corresponding layers of a solid carrier which is contacted with the sample. If a target analyte is present, the reaction of the liquid sample and reagents leads to a detectable signal, in particular a colour change, which can be evaluated visually or with the aid of an instrument, usually by reflection photometry.
Test elements or test carriers are often in the form of test strips which are essentially composed of an elongate support layer made of plastic material and detection layers which are applied thereto as test fields. However, test carriers are also known which are in the shape of small quadratic or rectangular plates. Test elements for clinical diagnostics that are evaluated visually or by reflection photometry are frequently constructed such that the sample application zone and the detection zone are arranged one above the other in a vertical axis. This mode of construction is problematic. When the test strip loaded with sample has to be inserted into an instrument, for example a reflection photometer, for measurement, potentially infectious sample material can come into contact with parts of the instrument and may contaminate them. Furthermore volumetric dosing can only be achieved with difficulty especially in cases in which the test strips are used by untrained persons for example in the self-control of blood sugar by diabetics. Moreover conventional test elements often require relatively large sample volumes due to their construction in order to enable reliable measurements. The more sample volume is required, the more painful this can be for the patient whose blood is to be examined. It is therefore a general goal to provide test strips which require as little sample material as possible.
An instrument for the analysis of biological fluids is known from DE-A 31 51 291 which has a carrier with a self-filling measurement channel as well as a laminate arrangement containing a filter layer and a reagent material layer. In this test carrier the sample liquid is transported into the measurement channel by capillary forces and from this it penetrates into the overlying laminate where a detection reaction for the target analyte takes place after heating the analytical instrument. A disadvantage is that the analytical instrument with the sample contained therein must be heated to achieve a measurement result. As a result the use of the analytical instrument is essentially limited to laboratories.
In DE-A 195 23 049 a multilayer analytical element is described containing a sample application zone and a detection zone arranged next to one another. The multilayer analytical element is essentially composed of a sandwich of a fleece and a porous membrane which are in a contact enabling liquid transfer over the whole area and in which the membrane and the sample application zone is treated in such a way that it does not take up or transport liquid in this area. The multilayer analytical element from DE-A 195 23 049 can be used in a test strip which contains a capillary gap by which means the sample liquid can be contacted with the sample application zone.
The object of the present invention was to eliminate the disadvantages of the prior art. In particular it was intended to provide a simple to handle test element that can automatically dose volumes and enables a spatial separation of the detection zone and sample application site while using minimal sample volumes. In addition the sample transport from sample application to the detection zone should be so rapid that this does not limit the time required to analyse a sample. Furthermore a simple construction of the test element should enable the test element to be manufactured cost-effectively and simply.
This is achieved by the subject matter of the invention as characterized in the patent claims.
The subject matter of the invention is an analytical test element for the determination of an analyte in a liquid containing a detection element and a channel capable of capillary liquid transport which has a sample application opening at one end of the channel capable of capillary liquid transport characterized in that the channel capable of capillary liquid transport is continuously narrowed from the sample application opening in the direction of capillary transport at least up to the beginning of the detection element.
The narrowing of the capillary-active channel serves to ensure that the sample volume located in the capillary channel can be reliably absorbed by the detection element without separation of the column of sample liquid. The risk with a channel that becomes narrower is that the liquid column is disrupted when the sample liquid is transferred from the inside of the channel onto the detection element, only part of the liquid in the capillary-active channel reaches the detection element and hence an underdosage of the detection zone results. This is counteracted by the narrowing according to the invention. The narrowing of the channel capable of capillary liquid transport preferably relates to that dimension of the channel which causes its capillarity. For capillaries with a rectangular cross-section this is usually the height of the channel. In this connection the height of the channel is that dimension that forms a right angle with the direction of transport of liquid in the channel and furthermore is essentially perpendicular to the plane of the detection element which is exposed for observation or measurement. In contrast to the height, the width of the channel is essentially parallel to the said plane of the detection element. The continuous narrowing of the channel towards the detection element also continuously increases the capillarity. If sample liquid now passes from the channel into the detection element, the higher capillarity in the channel on the side of the detection element causes sample liquid to move up from the regions of lower capillarity. In this manner a complete filling of the detection element is achieved which is associated with an—in the ideal case complete—emptying of the channel. Therefore no more sample has to be taken up into the channel than is required for the detection element.
In a preferred embodiment the narrowing of the channel capable of capillary liquid transport is linear from the sample application opening to the detection element. However, other forms of narrowing are also conceivable such as a slightly curved variant. In other words this means that the cross-section of the capillary-active channel at the sample application opening is larger than at the opposite end of the channel which is located under the detection element.
It is particularly preferred that the channel capable of capillary liquid transport is terminated at the opposite end to the sample application opening by an abrupt widening of that dimension of the channel which causes its capillarity. Such an abrupt widening can also be referred to as a height step.
The channel capable of capillary liquid transport preferably extends in the direction of capillary transport from the sample application opening to at most the border of the detection zone of the detection element that faces the sample application opening. In a particularly preferred embodiment the dimensions of the capillary channel are matched to the detection element in such a way that the maximum sample volume which the capillary channel c
Roche Diagnostics GmbH
Siefke Sam P.
Warden Jill
Woodburn Jill L.
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