Patent ID: 8083924

Claim:
A coulometric sensor for determining the concentration of glucose in a sample fluid, the sensor comprising: a working electrode and a counter electrode, wherein the working electrode and counter electrode are separated by an effective distance in a range of 25 to 1000 μm; a sample chamber for holding the sample fluid, the sample chamber comprising the working electrode, the counter electrode, a first indicator electrode to indicate when the sample chamber is beginning to fill with sample, and a second indicator electrode to indicate when the sample chamber is substantially filled with sample, wherein the sample chamber is sized to contain a volume of no more than about 1 μL of the sample; and a glucose-responsive enzyme and a diffusible redox mediator disposed in the sample chamber, wherein a background signal generated by the diffusible redox mediator in the absence of glucose is no more than 25% of the signal generated by oxidation or reduction of 80 mg/dL of glucose.