LOW OXYGEN IN VIVO ANALYTE SENSOR

• US 20080208025A1
• Filed: 05/01/2008
• Published: 08/28/2008
• Est. Priority Date: 03/04/1997
• Status: Active Grant

Abstract

The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous and subcutaneous measurement of glucose in a host.

Claims

1. A continuous glucose sensor system comprising:

an implantable body comprising an electrode configured to measure a glucose level in a host;

a membrane disposed over the electrode, wherein the membrane comprises a resistance domain configured to limit transport of glucose to the electrode and an enzyme to catalyze a reaction of glucose and oxygen as a co-reactant; and

a sensor electronics unit operably connected to the electrode and configured to measure a current produced by the electrode with substantial linearity at glucose concentrations of up to about 400 mg/dL in a fluid with an oxygen concentration of less than about 0.6 mg/L.

2. The continuous glucose sensor system of claim 1, wherein the sensor electronics unit is configured to measure glucose in a fluid with an oxygen concentration of less than about 0.3 mg/L.

3. The continuous glucose sensor system of claim 1, wherein the sensor electronics unit is configured to measure glucose in a fluid with an oxygen concentration of less than about 0.15 mg/L.

4. The continuous glucose sensor system of claim 1, wherein the sensor electronics unit is configured to measure glucose in a fluid with an oxygen concentration of less than about 0.05 mg/L.

5. The continuous glucose sensor system of claim 1, wherein the sensor electronics unit is configured to measure glucose in a fluid with an oxygen concentration of less than about 0.02 mg/L.

6. The continuous glucose sensor system of claim 1, wherein the electrode comprises an exposed electroactive working electrode surface with a surface area of from about 0.00002 in² to about 0.0079 in².

7. The continuous glucose sensor system of claim 1, wherein the resistance domain is configured to have a permeability ratio of at least about 50:

1 of glucose to oxygen.

8. The continuous glucose sensor system of claim 7, wherein the resistance domain is configured to have a permeability ratio of at least about 200:

1 of glucose to oxygen.

9. The continuous glucose sensor system of claim 1, wherein the sensor system is configured to have, in operation, a sensitivity of from about 1 pA/mg/dL to about 100 pA/mg/dL.

10. The continuous glucose sensor system of claim 1, wherein the sensor system is configured to have, in operation, a sensitivity of from about 5 pA/mg/dL to about 25 pA/mg/dL.

11. The continuous glucose sensor system of claim 1, wherein the system is configured such that less than about 1 μ

g of enzyme is consumed over 7 days of continuous operation.

12. A continuous glucose sensor, comprising:

a sensor configured for transcutaneous insertion through a skin of a host, wherein the sensor comprises an electrode configured to measure a glucose level in a host;

sensor electronics configured to configured to measure a signal produced by the electrode and convert the signal to a digital value with a resolution of at least about 1 mg/dL glucose/digital value.

13. The sensor of claim 12, wherein the sensor electronics comprise a current to frequency converter configured to continuously integrate the measured signal to provide the digital value.

14. The sensor of claim 12, wherein resolution is at least about 0.003 mg/dL glucose/digital value.

15. A continuous glucose sensor, comprising:

a sensor configured for transcutaneous insertion through a skin of a host, wherein the sensor comprises an electrode configured to measure a glucose level in a host;

a membrane disposed over the electrode, wherein the membrane comprises a resistance domain configured to limit transport of glucose to the electrode and an enzyme to catalyze a reaction of glucose and oxygen as a co-reactant, wherein the sensor is configured such that less than about 1 μ

g of enzyme is consumed over 7 days of continuous operation.