Dual electrode system for a continuous analyte sensor

• US RE44,695 E1
• Filed: 05/01/2012
• Issued: 01/07/2014
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Simpson, Peter C., Brauker, James H., Goode, Paul V., Kamath, Apurv Ullas, Petisce, James R.
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): D'ANGELO, MICHAEL J
• Application Number:
  US13/461,625
• Time in Patent Office: 616 Days
• Field of Search: 600/309, 600345-347, 600/365
• US Class Current: 600/345
• 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 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing

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 analyte or non-analyte related signal, both of which electrode include an interference domain.

Claims

1. A continuous glucose monitoring system configured for measuring glucose concentration in a host, the system comprising:

a continuous glucose sensor comprising a first working electrode disposed beneath an active enzymatic portion of a membrane system and configured to generate a first signal, and a second working electrode disposed beneath an inactive-enzymatic or a non-enzymatic portion of the membrane system and configured to generate a second signal, wherein the membrane system is configured to substantially reduce interfering species from reaching the first working electrode and the second working electrode; and

electronics configured to process the first signal and the second signal to produce a glucose signal that is substantially without signal contribution from interfering species, and to monitor the second signal for a change in amplitude above a threshold.

2. The system of claim 1, wherein the membrane system comprises an interference domain.

8. The system of claim 2, wherein the interference domain comprises a cellulosic derivative.

9. The system of claim 8, wherein the cellulosic derivative comprises at least at least one of cellulose acetate and cellulose acetate butyrate.

10. The system of claim 8, wherein the cellulosic derivative comprises a blend from about 1.5 parts to about 60 parts of cellulose acetate butyrate to one part of cellulose acetate.

11. The system of claim 8, wherein the cellulosic derivative comprises a cellulose acetate with a molecular weight of about 30,000 daltons to about 100,000 daltons.

12. The system of claim 8, wherein the interference domain is configured to substantially block passage therethrough of at least one interferent selected from the group consisting of acetaminophen, ascorbic acid, dopamine, ibuprofen, salicylic acid, tolbutamide, tetracycline, creatinine, uric acid, ephedrine, L-dopa, methyl dopa and tolazamide.

13. The system of claim 8, wherein the interference domain is configured to substantially block acetaminophen passage therethrough, wherein an eqivalent glucose signal response of the acetaminophen is less than about 30 mg/dl.

3. A method for providing a substantially noise-free glucose signal for a glucose sensor implanted in a host, the method comprising:

providing a glucose sensor, the glucose sensor comprising a first working electrode disposed beneath an active enzymatic portion of a membrane system, and a second working electrode disposed beneath an inactive-enzymatic or a non-enzymatic portion of the membrane system, wherein the membrane system is configured to substantially reduce one or more interfering species from reaching the first working electrode and the second working electrode;

generating a first signal associated with the first working electrode;

generating a second signal associated with the second working electrode;

processing the first signal and the second signal to produce a glucose signal that is substantially without signal contribution from interfering species; and

monitoring the second signal for a change in amplitude above a threshold.

4. The method of claim 3, further comprising requesting an external reference value when the change is above the threshold.

5. The method of claim 3, further comprising not calibrating the glucose signal when the change is above the threshold.

6. The method of claim 3, further comprising determining an instability of the glucose signal when the change is above the threshold.

7. The system method of claim 6, further comprising controlling a display of the glucose signal based on the determined instability.

14. The method of claim 3, wherein the membrane system comprises an interference domain comprising a cellulosic derivative.

15. The method of claim 14, wherein the cellulosic derivative comprises at least at least one of cellulose acetate and cellulose acetate butyrate.

16. The method of claim 14, wherein the cellulosic derivative comprises a blend from about 1.5 parts to about 60 parts of cellulose acetate butyrate to one part of cellulose acetate.

17. The method of claim 14, wherein the cellulosic derivative comprises a cellulose acetate with a molecular weight of about 30,000 daltons to about 100,000 daltons.

18. The method of claim 14, wherein the interference domain is configured to substantially block passage therethrough of at least one interferent selected from the group consisting of acetaminophen, ascorbic acid, dopamine, ibuprofen, salicylic acid, tolbutamide, tetracycline, creatinine, uric acid, ephedrine, L-dopa, methyl dopa and tolazamide.

19. The method of claim 14, wherein the interference domain is configured to substantially block acetaminophen passage therethrough, wherein an equivalent glucose signal response of the acetaminophen is less than about 30 mg/dl.