Patent ID: 7862695

Claim:
An electrochemical sensor for detecting the concentration of an analyte in a fluid test sample, the sensor comprising: a flow path for receiving the fluid test sample; a first lead and a second lead each adapted to be electrically coupled with a detector of electrical current; a working electrode disposed along the flow path, the working electrode being in electrical communication with the first lead; a counter electrode in electrical communication with the second lead, the counter electrode having a low-resistance portion and a high-resistance portion, the low-resistance portion of the counter electrode being disposed along the flow path downstream from the working electrode, the high-resistance portion of the counter electrode being disposed along the flow path upstream from the working electrode, the high-resistance portion including a resistor; and a reagent disposed on the working electrode, the reagent being adapted to react with the analyte to produce electrons that are transferred to the working electrode; wherein a first current profile is produced at the first and second leads in response to a voltage profile applied to the first and second leads when electrical communication occurs between only the high-resistance portion of the counter electrode and the working electrode, a second current profile is produced at the first and second leads in response to substantially the same voltage profile applied to the first and second leads when electrical communication occurs between the low-resistance and high-resistance portions of the counter electrodes and the working electrode, the first current profile being different than the second current profile.