Multi-layer reagent test strip

Abstract

A reagent test strip for measuring an analyte concentration in a biological fluid has a spreading mesh sandwiched between a support and a reagent matrix. The support has a through hole that is covered by the mesh. In use, a sample of the fluid is applied through the hole in the support to the spreading mesh. The sample then passes through the mesh to the matrix, which contains a reagent that indicates the analyte concentration by causing a corresponding change in reflectance at its free surface. Optionally, an adhesive layer attaches the mesh, and optionally the matrix as well, to the support.

We claim:  
     
         1 . A reagent test strip for use in an apparatus for measuring an analyte concentration in a biological fluid, comprising 
 (a) a support having a top surface, a bottom surface opposite, and a through hole for passing a sample of the biological fluid,    (b) a mesh, having a first surface adjoining the bottom surface of and covering the hole in, the support, and    (c) a reagent matrix adjoining a second surface of the mesh, opposite the first surface, the matrix comprising 
 (i) a sample receiving surface for receiving the sample from the mesh and passing at least a portion of the sample toward a testing surface opposite to the receiving surface and  
 (ii) a reagent for indicating the analyte concentration, by creating at the testing surface a change in reflectance that can be related to the analyte concentration.  
   
     
     
         2 . The test strip of  claim 1 , in which the analyte is glucose and the biological fluid is blood.  
     
     
         3 . The test strip of  claim 1 , in which the support comprises a thermoplastic sheet.  
     
     
         4 . The test strip of  claim 1 , in which the top surface of the support and the mesh provide high visual contrast.  
     
     
         5 . The test strip of  claim 1 , in which the mesh is brightly colored or fluorescent.  
     
     
         6 . The test strip of  claim 1 , in which the mesh is hydrophilic.  
     
     
         7 . The test strip of  claim 1 , in which the mesh is substantially non-absorbing of the biological fluid.  
     
     
         8 . The test strip of  claim 1 , in which the mesh comprises polyester or polyamide filament.  
     
     
         9 . The test strip of  claim 1 , in which the mesh has an open area that exceeds 50% of its total area.  
     
     
         10 . The test strip of  claim 1 , in which the mesh is attached to the support with a pressure-sensitive adhesive.  
     
     
         11 . The test strip of  claim 10 , in which the adhesive is not present where the mesh covers the hole.  
     
     
         12 . The test strip of  claim 10 , in which at least a part of the adhesive extends through the mesh and attaches the matrix to the support.  
     
     
         13 . The test strip of  claim 10 , in which the adhesive is hydrophobic.  
     
     
         14 . The test strip of  claim 1 , in which the matrix comprises a polyamide membrane.  
     
     
         15 . The test strip of  claim 1 , in which the matrix is an anisotropic membrane, with larger pores near the sample receiving surface and smaller pores near the testing surface.  
     
     
         16 . The test strip of  claim 2  in which the reagent comprises a dye precursor that forms a chromophore indicative of the glucose concentration.  
     
     
         17 . The test strip of  claim 16 , in which the dye precursor comprises 3-methyl-2-benzothiazolinone hydrazone hydrochloride and dimethylaminobenzoic acid.  
     
     
         18 . The test strip of  claim 16 , in which the dye precursor comprises meta [3-methyl 2-benzothiazolinone hydrazone] N-sulfonyl benzenesulfonate monosodium and 8-anilino-1-naphthalene sulfonic acid.  
     
     
         19 . The test strip of  claim 17 , in which the matrix comprises a polyamide membrane.  
     
     
         20 . The test strip of  claim 18 , in which the matrix comprises an anisotropic membrane with larger pores near the receiving surface and smaller pores near the testing surface.