Biosensing meter which detects proper electrode engagement and distinguishes sample and check strips

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG.
1, sample strip 10 comprises a pair of electrodes 12 and 14 which are supported on a polymeric support 16.
A cover sheet 18 is provided with openings 20 and 24 which expose electrodes 12 and 14.
Opening 20 creates a well and defines a reaction zone between electrodes 12 and 14.
A layer (not shown) of enzymatic reactants overlays electrodes 12 and 14 and provides a substrate on which an analyte--containing fluid sample can be emplaced.
Opening 24 exposes electrodes 12 and 14 so that when sample strip 10 is inserted into a biosensing meter, electrical connection can be made thereto.
In FIG.
2, a check strip 30 is shown that is employed to determine the operability of the biosensing meter and to enable an exercise of certain of its measurement functions.
Check strip 30 includes a pair of electrodes 32 and 34 which correspond in placement to sense and excitation electrodes 12 and 14 (FIG.
1) respectively.
Electrode 32 is foreshortened and is bounded by an L-shaped electrode 36 that is shorted by wire 38 to electrode 34.
A resistance 40 connects electrodes 32 and 36 to electrode 32.
As will be hereafter understood, check strip 30 enables an exercise of a biosensing meter's measurement functions.
In FIG.
3, a schematically illustrated biosensing meter 50 includes a window (not shown) for accepting either a sample strip 10 or a check strip 30.
In FIG.
3, the distal portion of a sample strip 10 is shown in the inserted position.
Excitation electrode 14, if it is continuous and properly inserted, electrically connects contacts A and B.
Similarly, sense electrode 12 electrically shorts contacts C and D if sample strip 10 is properly inserted and a proper level of contact resistance is present.
Contacts A, B and C, D are respectively spaced apart within biosensing meter 50 and enable a determination to be made that a sample strip 10 has been properly inserted and that its electrodes reflect the proper impedance states.
Once such determinations are made, sample strip 10 may be dosed, i