Determination of blood glucose in a small volume and in a short test time using a chemical coating inluding binders and very short read potentials

Abstract

Analytes in a liquid sample are determined by methods utilizing sample volumes of less than about 1.0 μl and test times within about eight seconds. The methods are preferably performed using small test strips including a sample receiving chamber filled with the sample by capillary action.

1 . A method of determining the concentration of glucose in a blood sample, comprising:
 providing a disposable biosensor test strip including a capillary chamber having a depth suitable for capillary flow of blood, and holding a volume of from 0.25 μl to less than 1 μl of the blood sample, the capillary chamber including a working electrode, a counter or reference electrode, and a chemical coating, the chemical coating being proximal to at least the working electrode, the chemical coating including a chemical reagent proximal to or in contact with at least the working electrode and including an enzyme and a mediator, the chemical coating further including one or more binders;   applying a blood sample containing glucose into the capillary chamber, the capillary chamber directing capillary flow of the blood sample into contact with the chemical reagent to cause the blood sample to at least partially solubilize or hydrate the chemical reagent, the glucose reacting with the chemical reagent to produce an electroactive reaction product;   detecting the blood sample in the capillary chamber;   following said detecting, providing a delay period prior to the application of an electrooxidation assay potential of about 100 mV to about 500 mV across the working and counter or reference electrode;   following said delay period, applying an electrooxidation assay potential of about 100 mV to about 500 mV across the working and counter or reference electrodes for a period of about 1.5 seconds to about 6 seconds;   electrooxidizing the electroactive reaction product at the working electrode, said electrooxidizing producing an assay current;   measuring the assay current at one or more times during application of the assay potential;   correlating the one or more assay current measurements to the concentration of glucose in the blood sample; and   from about 2 seconds to about 8 seconds after said detecting, providing a readout of the glucose concentration in the blood sample.