Dual electrode system for a continuous analyte sensor

• US 7,460,898 B2
• Filed: 10/04/2006
• Issued: 12/02/2008
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Brister, Mark, Petisce, James R., Saint, Sean, Pryor, Jack, Simpson, Peter, Hanson, Curtis
• Primary Examiner(s): Nasser; Robert L
• Application Number:
  US11/543,707
• Publication Number:
  US 20070027385A1
• Time in Patent Office: 790 Days
• Field of Search: None
• US Class Current: 600/347
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6848 Needles
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

Disclosed herein are systems and methods for a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes first and second working electrodes to measure additional analyte or non-analyte related signal. Such measurements may provide a background and/or sensitivity measurement(s) for use in processing sensor data and may be used to trigger events such as digital filtering of data or suspending display of data.

Claims

1. An analyte sensor configured for insertion into a host for measuring an analyte in the host, the sensor comprising:

a first working electrode comprising a first electroactive surface disposed beneath an active enzymatic portion of a sensor membrane, wherein the first working electrode is configured to generate a first signal; and

a second working electrode comprising a second electroactive surface disposed beneath an inactive-enzymatic or a non-enzymatic portion of a sensor membrane, wherein the second working electrode is configured to generate a second signal, wherein the first electroactive surface and the second electroactive surface are configured and arranged to be equivalently influenced by in vivo environmental factors when implanted in a host such that a signal component associated with the in vivo environmental factors can be removed from the first signal, wherein the first and second electrodes are configured and arranged around a circumference of the sensor along an overlapping length of the sensor.

2. The sensor of claim 1, wherein the first working electrode and the second working electrode are coaxial.

3. The sensor of claim 1, wherein at least one of the first working electrode and the second working electrode is twisted or helically wound to integrally form at least a portion of the sensor.

4. The sensor of claim 3, wherein the first working electrode and the second working electrode are twisted together to integrally form an in vivo portion of the sensor.

5. The sensor of claim 1, wherein the first working electrode and the second working electrode each comprise a first end and a second end, wherein the first ends are configured for insertion in the host, and wherein the second ends are configured for electrical connection to sensor electronics.

6. The sensor of claim 5, wherein the second ends are coaxial.

7. The sensor of claim 5, wherein the second ends are stepped.

8. The sensor of claim 1, further comprising at least one additional electrode selected from the group consisting of a reference electrode and a counter electrode.

9. The sensor of claim 8, wherein the additional electrode, together with the first working electrode and the second working electrode, integrally form at least a portion of the sensor.

10. The sensor of claim 8, wherein the additional electrode is located at a position remote from the first and second working electrodes.

11. The sensor of claim 8, wherein a surface area of the additional electrode is at least six times a surface area of at least one of the first electroactive surface and the second electroactive surface.

12. The sensor of claim 1, wherein the sensor is configured for implantation into the host.

13. The sensor of claim 12, wherein the sensor is configured for subcutaneous implantation in a tissue of a host.

14. The sensor of claim 12, wherein the sensor is configured for indwelling in a blood stream of a host.

15. The sensor of claim 1, wherein the sensor substantially continuously measures an analyte concentration in a host.

16. The sensor of claim 1, wherein the sensor comprises a glucose sensor, and wherein the first working electrode is configured to generate a first signal associated with glucose and non-glucose related electroactive compounds, the glucose and non-glucose related electroactive compounds having a first oxidation potential.

17. The sensor of claim 16, wherein the second working electrode is configured to generate a second signal associated with noise of the glucose sensor, the noise comprising signal contribution due to non-glucose related electroactive compounds with an oxidation potential that substantially overlaps with the first oxidation potential.

18. The sensor of claim 17, wherein the non-glucose related electroactive species comprises at least one species selected from the group consisting of interfering species, non-reaction-related hydrogen peroxide, and other electroactive species.

19. The sensor of claim 1, further comprising electronics operably connected to the first working electrode and the second working electrode, and configured to provide the first signal and the second signal to generate glucose concentration data substantially without signal contribution due to non-glucose-related noise.

20. The sensor of claim 1, further comprising a non-conductive material positioned between the first working electrode and the second working electrode.

21. The sensor of claim 1, wherein each of the first working electrode, the second working electrode, and the non-conductive material are configured to provide at least two functions selected from the group consisting of electrical conductance, insulative property, structural support, and diffusion barrier.

22. The sensor of claim 1, wherein the sensor comprises a diffusion barrier configured to substantially block diffusion of at least one of an analyte and a co-analyte between the first working electrode and the second working electrode.

23. The sensor of claim 1, wherein the first and second electrodes are symmetric about a longitudinal axis of the sensor.

24. The sensor of claim 1, wherein a surface area of the first electroactive surface is equal to a surface area of the second electroactive surface.

25. The sensor of claim 24, wherein the second ends are coaxial.

26. The sensor of claim 24, wherein the second ends are stepped.

27. The sensor of claim 1, wherein the sensor membrane comprises an interference domain located over the first and second electroactive surfaces.

28. A system configured for measuring a glucose concentration in a host, the system comprising:

a first working electrode comprising a first electroactive surface disposed beneath an active enzymatic portion of a sensor membrane;

a second working electrode comprising a second electroactive surface disposed beneath an inactive-enzymatic or a non-enzymatic portion of a sensor membrane, wherein the first and second electrodes are at least one of bundled and twisted together in a configuration, whereby the first and second electroactive surfaces measure noise caused by the host'"'"'s metabolic processes in the surrounding micro-environment after in vivo insertion of the sensor into the host; and

a processor module configured to receive or process a first signal from the first working electrode associated with glucose and non-glucose related electroactive compounds, the glucose and non-glucose related electroactive compounds having a first oxidation potential, and to receive or process a second signal from the second working electrode associated with non-glucose related electroactive compounds with an oxidation potential that substantially overlaps with the first oxidation potential, and wherein the processor module is further configured to process the first signal and the second signal to generate glucose concentration data substantially without signal contribution due the noise caused by the host'"'"'s metabolic processes.

29. The sensor of claim 28, wherein the first working electrode and the second working electrode are coaxial.

30. The sensor of claim 28, wherein the first working electrode and the second working electrode form a double helix configuration.

31. The sensor of claim 28, wherein the first working electrode and the second working electrode each comprise a first end and a second end, wherein the first ends are configured for insertion in the host, and wherein the second ends are configured for electrical connection to sensor electronics.

32. The sensor of claim 31, wherein the second ends are coaxial.

33. The sensor of claim 31, wherein the second ends are stepped.

34. The sensor of claim 28, wherein a surface area of the first electroactive surface is equal to a surface area of the second electroactive surface.

35. The sensor of claim 28, wherein the first and second electrodes are symmetric about a longitudinal axis of the sensor.

36. The sensor of claim 28, wherein the first and second electrodes are configured and arranged around a circumference of the sensor.

37. The sensor of claim 28, wherein the sensor membrane comprises an interference domain located over the first and second electroactive surfaces.

38. An analyte sensor configured for insertion into a host for measuring an analyte in the host, the sensor comprising:

a first working electrode disposed beneath an active enzymatic portion of a sensor membrane and configured to generate a first signal; and

a second working electrode disposed beneath an inactive-enzymatic or a non-enzymatic portion of a sensor membrane and configured to generate a second signal, wherein the first and second electroactive surfaces are configured and arranged around a circumference of the sensor along an overlapping length of the sensor.

39. The sensor of claim 38, wherein the sensor membrane comprises an interference domain located over the first and second electroactive surfaces.