Dual electrode system for a continuous analyte sensor

• US 9,504,413 B2
• Filed: 04/15/2013
• Issued: 11/29/2016
• Est. Priority Date: 10/04/2006
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Simpson, Peter C., Brister, Mark, Wightlin, Matthew, Pryor, Jack
• Primary Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US13/863,204
• Publication Number:
  US 20130231542A1
• Time in Patent Office: 1,324 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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 5/6849 in combination with a needle set
• CPC Class Codes: C12Q 1/006 for glucose

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. A continuous glucose sensor configured and arranged for insertion into a host for and detecting glucose in the host, the sensor comprising:

a first working electrode comprising a first electroactive surface, wherein the first working electrode is configured to generate a first signal, wherein the first working electrode is configured to switch from a first bias potential to a second bias potential, wherein the first bias potential is a glucose measurement potential and the second bias potential is a non-glucose-measurement potential;

a second working electrode comprising a second electro active surface wherein the second working electrode is configured to generate a second signal; and

sensor electronics configured to compare the first signal with the second signal and determine a level of glucose in the host based at least in part on the comparison of the first signal with the second signal.

2. The sensor of claim 1, wherein the sensor is configured to perform pulsed amperometric detection.

3. The sensor of claim 1, wherein the sensor is configured to perform a stepped potential waveform.

4. The sensor of claim 3, wherein the sensor further comprises a reference and a counter electrode.

5. The sensor of claim 4, wherein the sensor further comprises a reference and a counter electrode.

6. The sensor of claim 1, wherein the second working electrode is configured to switch from a third bias potential to a fourth bias potential.

7. The sensor of claim 1, wherein the first bias potential is held long enough to allow equilibration.

8. The sensor of claim 1, wherein the sensor electronics are configured to calculate at least one glucose sensor data point using the first and second signals.

9. The sensor of claim 1, wherein the sensor electronics are configured to process the first and second signals to generate a glucose concentration substantially without signal contribution due to non-glucose noise artifacts.

10. The sensor of claim 1, wherein the sensor is configured to oscillate potential between the first working electrode and the second working electrode.

11. A continuous glucose sensor configured and arranged for insertion into a host for and detecting glucose in the host, the sensor comprising:

a first working electrode comprising a first resistance domain, wherein the first working electrode is configured to generate a first signal having a first noise component related to a noise-causing species;

a second working electrode comprising a second resistance domain, wherein the second working electrode is configured to generate a second signal having a second noise component related to the noise-causing species;

a third resistance domain disposed continuously over the first resistance domain and the second resistance domain;

wherein each of the first resistance domain and the second resistance domain is independently formed on the first working electrode and the second working electrode, respectively.

12. The sensor of claim 11, wherein the noise-causing species comprises at least one member selected from the group consisting of externally produced H2O2, urea, lactic acid, phosphates, citrates, peroxides, amino acids, amino acid precursors, amino acid break-down products, nitric oxide, NO-donors, NO-precursors, reactive oxygen species, compounds having electroactive acidic, amine or sulfhydryl groups, acetaminophen, ascorbic acid, dopamine, ephedrine, ibuprofen, L-dopa, methyldopa, salicylate, tetracycline, tolazamide, tolbutamide, and triglycerides.

13. The sensor of claim 11, wherein the noise-causing species is non-constant.

14. The sensor of claim 11, wherein the first signal comprises a first sensitivity and the second signal comprises a second sensitivity, and wherein the third resistance domain is configured such that the first sensitivity and the second sensitivity are substantially equivalent.

15. The sensor of claim 14, wherein the first sensitivity and the second sensitivity are equivalent to ±

10%.

16. The sensor of claim 11, wherein the first working electrode comprises a first electroactive surface and a first membrane portion disposed thereon, the first membrane portion comprising an active enzymatic enzyme domain and the first resistance domain, and wherein the second working electrode comprises a second electroactive surface and a second membrane portion disposed thereon, the second membrane portion comprising at least one of an inactive enzymatic portion or a non-enzymatic portion and the second resistance domain.

17. The sensor of claim 16, wherein the active enzymatic enzyme domain is configured to generate a measurable species.

18. The sensor of claim 17, wherein the measurable species comprises H2O2 produced in the active enzymatic portion of the sensor membrane.

19. The sensor of claim 17, wherein the crosstalk distance comprises a distance less than a maximum distance the measurable species can diffuse, and generate a signal associated with crosstalk.

20. The sensor of claim 17, wherein the first electroactive surface and the second electroactive surface are spaced a distance that allows noise caused by a local point source that produces noise-causing species to be measured equivalently at the first and second electroactive surfaces.

21. The sensor of claim 17, wherein each of the first electroactive surface and the second electroactive surface is configured and arranged to integrate the signal caused by a plurality of local point sources that produce noise-causing species in vivo, such that the first noise component and the second noise component are substantially equivalent.

22. The sensor of claim 17, wherein the first electroactive surface and the second electroactive surface are configured and arranged to integrate signals detected about a circumference of the sensor.

23. The sensor of claim 17, wherein the dimension of each of the first electroactive surface and the second electroactive surface is greater than a sum of diameters of about 10 average human cells.

24. The sensor of claim 23, wherein the dimension of each of the first electroactive surface and the second electroactive surface is greater than about 500 μ

m.

25. The sensor of claim 16, further comprising a physical diffusion barrier, wherein physical diffusion barrier comprises the first resistance domain and the second resistance domain.

26. The sensor of claim 25, wherein the physical diffusion barrier is configured and arranged to physically block some crosstalk from the active enzymatic enzyme domain to the second electroactive surface.

27. The sensor of claim 25, wherein the physical diffusion barrier is configured and arranged to physically block an amount of a measurable species diffusing from the active enzymatic enzyme domain to the second electroactive surface, such that there is substantially no signal associated with crosstalk measured at the second working electrode.

28. The sensor of claim 25, wherein the physical diffusion barrier comprises a first barrier layer formed on the first working electrode and a second barrier layer formed on the second working electrode, wherein each of the first barrier layer and the second barrier layer is independently formed.

29. A continuous glucose sensor configured and arranged for insertion into a host for and detecting glucose in the host, the sensor comprising:

a first working electrode comprising a first resistance domain,

wherein the first working electrode comprises a first electroactive surface and a first membrane portion disposed thereon, wherein the first membrane portion comprising an active enzymatic enzyme domain and the first resistance domain, wherein the first working electrode is configured to generate a first signal having a first noise component related to a noise-causing species;

a second working electrode comprising a second resistance domain, wherein the second working electrode comprises a second electroactive surface and a second membrane portion disposed thereon, wherein the second membrane portion comprises at least one of an inactive enzymatic portion or a non-enzymatic portion and the second resistance domain, wherein the second working electrode is configured to generate a second signal having a second noise component related to the noise-causing species; and

a third resistance domain disposed continuously over the first resistance domain and the second resistance domain;

a physical diffusion barrier, wherein physical diffusion barrier comprises the first resistance domain and the second resistance domain;

wherein the physical diffusion barrier is configured and arranged to attenuate diffusion of the measurable species from the active enzymatic enzyme domain to the second electroactive surface by at least 2-fold.

30. The sensor of claim 29, wherein the diffusion is attenuated by at least 10-fold.

31. The sensor of claim 29, wherein the noise-causing species comprises at least one member selected from the group consisting of externally produced H2O2, urea, lactic acid, phosphates, citrates, peroxides, amino acids, amino acid precursors, amino acid break-down products, nitric oxide, NO-donors, NO-precursors, reactive oxygen species, compounds having electroactive acidic, amine or sulfhydryl groups, acetaminophen, ascorbic acid, dopamine, ephedrine, ibuprofen, L-dopa, methyldopa, salicylate, tetracycline, tolazamide, tolbutamide, and triglycerides.

32. The sensor of claim 29, wherein the noise-causing species is non-constant.

33. The sensor of claim 29, wherein the first signal comprises a first sensitivity and the second signal comprises a second sensitivity, and wherein the third resistance domain is configured such that the first sensitivity and the second sensitivity are substantially equivalent.

34. A continuous glucose sensor configured and arranged for insertion into a host for and detecting glucose in the host, the sensor comprising:

a first working electrode comprising a first resistance domain, wherein the first working electrode comprises a first electroactive surface and a first membrane portion disposed thereon, wherein the first membrane portion comprises an active enzymatic enzyme domain and the first resistance domain, wherein the active enzymatic enzyme domain is configured to generate a measurable species, wherein the first working electrode is configured to generate a first signal having a first noise component related to a noise-causing species;

a second working electrode comprising a second resistance domain, wherein the second working electrode comprises a second electroactive surface and a second membrane portion disposed thereon, wherein the first electroactive surface and the second electroactive surface are spaced closer together than a crosstalk distance, wherein the second membrane portion comprises at least one of an inactive enzymatic portion or a non-enzymatic portion and the second resistance domain, wherein the second working electrode is configured to generate a second signal having a second noise component related to the noise-causing species;

a third resistance domain disposed continuously over the first resistance domain and the second resistance domain.

35. The sensor of claim 34, wherein the noise-causing species comprises at least one member selected from the group consisting of externally produced H2O2, urea, lactic acid, phosphates, citrates, peroxides, amino acids, amino acid precursors, amino acid break-down products, nitric oxide, NO-donors, NO-precursors, reactive oxygen species, compounds having electroactive acidic, amine or sulfhydryl groups, acetaminophen, ascorbic acid, dopamine, ephedrine, ibuprofen, L-dopa, methyldopa, salicylate, tetracycline, tolazamide, tolbutamide, and triglycerides.

36. The sensor of claim 34, wherein the noise-causing species is non-constant.

37. The sensor of claim 34, wherein the first signal comprises a first sensitivity and the second signal comprises a second sensitivity, and wherein the third resistance domain is configured such that the first sensitivity and the second sensitivity are substantially equivalent.

38. A continuous glucose sensor configured and arranged for insertion into a host for and detecting glucose in the host, the sensor comprising:

a first working electrode comprising a first resistance domain, wherein the first working electrode comprises a first electroactive surface and a first membrane portion disposed thereon, wherein the first membrane portion comprises an active enzymatic enzyme domain and the first resistance domain, wherein the active enzymatic enzyme domain is configured to generate a measurable species, wherein the first working electrode is configured to generate a first signal having a first noise component related to a noise-causing species;

a second working electrode comprising a second resistance domain, wherein the second working electrode comprises a second electroactive surface and a second membrane portion disposed thereon, wherein the second membrane portion comprises at least one of an inactive enzymatic portion or a non-enzymatic portion and the second resistance domain, wherein the second working electrode is configured to generate a second signal having a second noise component related to the noise-causing species; and

a third resistance domain disposed continuously over the first resistance domain and the second resistance domain;

wherein the first electroactive surface and the second electroactive surface are each sized in at least one dimension such that the first noise component and the second noise component can be integrated across the dimension.