Patent ID: 7589828

Claim:
A system for measuring an analyte in a body fluid sample, the system comprising; a meter with: a grey scale photodetector module; and a memory module; and at least one test strip, wherein the test strip includes: a substrate, the substrate having: a working surface for receiving the body fluid sample; and a reverse surface that is in opposition to the working surface; and a permutative grey scale calibration pattern disposed on at least one of the working surface and reverse surface, the permutative grey scale calibration pattern including at least a first grey scale region and a second grey scale region, wherein the grey scale shade of the at least first and second grey scale regions constitute a grey scale permutation that uniquely corresponds to a calibration code, and wherein the grey scale photodetector module is configured to detect the permutative grey scale calibration pattern of the test strip when the test strip is inserted into the meter, and wherein the memory module has stored therein a grey scale permutation matrix with a plurality of calibration codes, each of the calibration codes uniquely corresponding to a grey scale permutation of the permutative grey scale calibration pattern.