Ph microsensor for glucose and other analyte sensor fault detection

A method of calculating the concentration of glucose at a plurality of different pH values within an amperometric glucose sensor, the method comprising:

• (a) placing an amperometric glucose sensor into an environment comprising glucose, where the amperometric analyte sensor is disposed within a system comprising:
• a base;
• a plurality of electrodes disposed on the base including:
• a working electrode, wherein the working electrode is coated with:
• an analyte sensing layer comprising glucose oxidase that produces gluconic acid and hydrogen peroxide in the presence of glucose;
• and
• an analyte modulating layer, wherein the analyte modulating layer comprises a composition that modulates the diffusion of an analyte diffusing through the analyte modulating layer;
• a counter electrode;
• a reference electrode;
• a pH electrode responsive to changes in pH within the local sensor system environment;
• a processor;
• and
• a computer-readable program having instructions which cause the processor to:
• assess signal data obtained from the working electrode and the pH electrode;
• wherein:
• the working electrode and the processor are coupled so that the working electrode monitors glucose within the sensor system;
• the pH electrode and the processor are coupled so that the pH electrode monitors the pH of the sensor within the sensor system;
• (b) monitoring the pH of the sensor within the sensor system;
• (c) monitoring glucose within the sensor system;
• and
• (d) calculating the concentration of glucose, wherein:
• the processor uses a first set of parameters to calculate a concentration of glucose when the pH of the analyte sensing layer is at or above pH 7.1;
• and
• the processor uses a second set of parameters to calculate a concentration of glucose when the pH of the analyte sensing layer is below pH 6.9.

A method of making an analyte sensor comprising the steps of:

• providing a base layer;
• forming a conductive layer on the base layer, wherein the conductive layer includes a plurality of electrodes including a pH electrode, a working electrode, a reference electrode and a counter electrode;
• forming an analyte sensing layer over the working electrode, wherein the analyte sensing layer comprises a polypeptide that forms an acidic compound in the presence of the analyte;
• and
• forming an analyte modulating layer disposed over the analyte sensing layer, wherein the analyte modulating layer includes a composition that modulates the diffusion of the analyte therethrough.
• forming an adhesion promoting layer on the analyte sensing layer or the protein layer;
• or
• forming a cover layer disposed on at least a portion of the analyte modulating layer, wherein the cover layer further includes an aperture over at least a portion of the analyte modulating layer.