ANALYTE SENSORS HAVING A SIGNAL-TO-NOISE RATIO SUBSTANTIALLY UNAFFECTED BY NON-CONSTANT NOISE

• US 20070235331A1
• Filed: 05/18/2007
• Published: 10/11/2007
• Est. Priority Date: 07/25/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Boock, Robert, Brister, Mark, Markovic, Dubravka, Woo, Kum Ming, Wightlin, Matthew, Pryor, Jack, Simpson, Peter, Nicholas, Melissa, Petisce, James, Rixman, Monica, Brunner, Seth, Nguyen, Lisa, Chee, Arthur
• Granted Patent: US 8,364,229 B2
• Time in Patent Office: Days
• US Class Current: 204/403.10
• CPC Class Codes: A61B 5/00 Measuring for diagnostic purposes radiation diagnosis A61B6/00; diagnosis by ultrasonic, sonic or infrasonic waves A61B8/00; Identification of persons
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14735 comprising an immobilised reagent
• 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 5/6848 Needles
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

Systems and methods of use involving sensors having a signal-to-noise ratio that is substantially unaffected by non-constant noise are provided for continuous analyte measurement in a host. In some embodiments, a continuous analyte measurement system is configured to be wholly, transcutaneously, intravascularly or extracorporeally implanted.

Claims

1. An electrochemical analyte sensor for determining a concentration of an analyte in a host, the sensor configured for insertion into a host, wherein the sensor comprises at least one electrode configured to measure an analyte concentration substantially continuously;

and electronics configured to provide a signal measured at the electrode;

wherein the signal comprises an analyte-related component and a noise component, wherein the noise component comprises a substantially non-constant non-analyte-related component; and

wherein the sensor is configured such that the substantially non-constant non-analyte related component does not substantially contribute to the signal, after sensor break-in, for at least about one day.

2. The analyte sensor of claim 1, wherein the analyte is glucose.

3. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 20% of the signal over a time period of at least about one day.

4. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 20% of the signal over a time period of at least about three days.

5. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 20% of the signal over a time period of at least about five days.

6. The analyte sensor of claim 3, wherein the analyte sensor comprises a membrane system disposed over the electrode.

7. The analyte sensor of claim 6, wherein the membrane system comprises glucose oxidase.

8. The analyte sensor of claim 7, wherein the membrane system is configured to inactivate at least one non-constant noise-causing electroactive species formed in a metabolic process of the host.

9. The analyte sensor of claim 8, wherein the non-constant noise-causing electroactive species comprises an electroactive species having a redox potential that substantially overlaps with a redox potential of a measured species indicative of the concentration of the analyte.

10. The analyte sensor of claim 9, wherein the measured species comprises hydrogen peroxide.

11. The analyte sensor of claim 9, wherein the at least one non-constant noise-causing electroactive species comprises at least one species selected from the group consisting of reactive oxygen species, nitrogen species, and hydrogen peroxide formed in a metabolic process of the host.

12. The analyte sensor of claim 6, wherein the membrane system is configured to substantially block passage therethrough of at least one non-constant noise-causing electroactive species formed in a metabolic process of the host.

13. The analyte sensor of claim 6, wherein the membrane system is configured to consume at least one non-constant noise-causing electroactive species formed in a metabolic process of the host.

14. The analyte sensor of claim 6, wherein at least a portion of the membrane system comprises a torturous diffusion path configured to render inactive, at the electrode, at least one non-constant noise-causing electroactive species formed in a metabolic process of the host.

15. The analyte sensor of claim 6, wherein the membrane system comprises a Heme compound.

16. The analyte sensor of claim 6, wherein the membrane system comprises a resistance domain configured to restrict flow of the analyte therethrough.

17. The analyte sensor of claim 16, wherein the resistance domain comprises a polymer comprising hydrophilic components and hydrophobic components.

18. The analyte sensor of claim 16, wherein the sensor is configured with electronics to detect the analyte with a sensitivity of from about 1 pA/mg/dl to about 500-pA/mg/dl.

19. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 10% of the signal over a time period of at least about one day.

20. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 5% of the signal over a time period of at least about one day.

21. The analyte sensor of claim 1, wherein a signal contribution due to the non-constant non-analyte-related component is less than about 1% of the signal over a time period of at least about one day.

22. The analyte sensor of claim 3, wherein the electrode comprises a dispersed electroactive surface area.

23. The analyte sensor of claim 22, wherein the dispersed electroactive surface area comprises a plurality of spaced electroactive surface areas.

24. The analyte sensor of claim 3, wherein the sensor is configured to measure the concentration of the analyte along a substantial length of an in vivo portion of the sensor.

25. The analyte sensor of claim 24, wherein the sensor comprises an in vivo portion, wherein an area of the electroactive surface covers at least about 50% the in vivo portion.

26. The analyte sensor of claim 3, wherein the electrode comprises an electroactive surface, wherein the sensor comprises a discontinuous portion, and wherein the electroactive surface is spaced from the discontinuous portion by a distance substantially farther than a diffusion distance of at least one non-constant noise-causing electroactive species formed in a metabolic process of the host

27. The analyte sensor of claim 3, wherein the in vivo portion of the sensor is tapered.

28. The analyte sensor of claim 1, wherein the analyte-related component of the signal is at least about 80% of the signal over a time period of at least about one day.

29. The analyte sensor of claim 28, wherein the analyte sensor comprises a membrane system disposed over the electrode and wherein the membrane system comprises an outer domain comprising a discontinuously hydrophilic surface.

30. The analyte sensor of claim 29, wherein the outer domain comprises at least about 5 wt. % of a hydrophilic component.

31. The analyte sensor of claim 30, wherein the hydrophilic component comprises polyethylene glycol.

32. The analyte sensor of claim 30, wherein the outer domain comprises at least about 10 wt. % of a hydrophilic component.

33. The analyte sensor of claim 30, wherein the outer domain comprises at least about 20 wt. % of a hydrophilic component.

34. The analyte sensor of claim 29, wherein the outer domain is configured to control a flux of the analyte therethrough.

35. The analyte sensor of claim 28, wherein the analyte sensor is configured to detect hydrogen peroxide via diffusion to the electrode, wherein the sensor comprises a membrane system disposed over the electrode, wherein the membrane system comprises an electrode domain adjacent to the electrode, wherein the electrode domain is configured to maintain a layer of water at electrochemically reactive surfaces of the sensor, and wherein the electrode domain comprises an enzyme configured for detecting the analyte.

36. The analyte sensor of claim 1, wherein the analyte sensor is configured for ambulatory wear.