Analyte sensor with increased reference capacity
Systems and methods of use for continuous analyte measurement of a host's vascular system are provided. In some embodiments, a continuous glucose measurement system includes an electrochemical sensor incorporating a silver/silver chloride reference electrode, wherein a capacity of the reference electrode is controlled.
1. An implantable electrochemical sensor for measuring an analyte concentration in a host, comprising:
a two-electrode sensor assembly configured to be implanted in a host and be exposed to interstitial fluid, wherein the two-electrode sensor assembly comprises:
a working electrode configured to measure a signal associated with a concentration of an analyte;
a reference electrode, wherein the reference electrode comprises a conductive material, wherein the reference electrode is configured to provide substantially stable reference potential for sixteen days while continuously responding to a signal current of 20 nA from the working electrode; and
an enzyme-containing membrane disposed over at least a portion of the working electrode, and wherein at least a portion of the reference electrode is in direct contact with the enzyme-containing membrane.
2. The implantable electrochemical sensor of claim 1 , wherein the enzyme-containing membrane comprises an oxidase enzyme.
3. The implantable electrochemical sensor of claim 1 , wherein the analyte is glucose.
4. The implantable electrochemical sensor of claim 1 , wherein the conductive material comprises silver chloride.
5. The implantable electrochemical sensor of claim 1 , wherein the reference electrode is formed of a chloridized elongated silver body.
6. The implantable electrochemical sensor of claim 1 , wherein the enzyme-containing membrane has a thickness from about 0.01 microns to about 12 microns thick.