Disposable glucose test strips, and methods and compositions for making same

DETAILED DESCRIPTION The present invention provides an improved disposable glucose test strip for use in a test meter of the type which receives a disposable test strip and a sample of blood from a patient and performs an electrochemical analysis of the amount of glucose in the sample.
The test strip comprises: (a) a substrate; (b) a reference electrode; (c) a working electrode; and (d) means for making an electrical connection between the reference and working electrode and a glucose test meter.
The working electrode comprises a conductive base layer disposed on the substrate and a non-conductive coating disposed over the conductive base layer.
The non-conductive coating comprises a filler which has both hydrophobic and hydrophilic surface regions, an enzyme effective to oxidize glucose, e.
g.
, glucose oxidase, and a mediator effective to transfer electrons from the enzyme to the conductive base layer.
The filler is selected to have a balance of hydrophobicity and hydrophilicity such that on drying it forms a two-dimensional network on the surface of the conductive base layer.
Preferred filler are non-conductive silica fillers.
The response of this test strip is dependent on the diffusion rate of glucose, not on the rate at which the enzyme can oxidize glucose, such that the performance of the test strip is essentially temperature independent over relevant temperature ranges.
Further, the silica appears to form a two-dimensional network which excludes red blood cells, thus rendering the test strip substantially insensitive to the hematocrit of the patient.