Implantable electrochemical biosensor system and method

• US 10,285,633 B2
• Filed: 03/02/2018
• Issued: 05/14/2019
• Est. Priority Date: 09/15/2009
• Status: Active Grant

• Current Assignee: Konamite Limited
• Original Assignee: Agamatrix Incorporated (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Inventors: Iyengar, Sridhar, Harding, Ian
• Primary Examiner(s): Jang, Christian
• Application Number:
  US15/910,251
• Publication Number:
  US 20180249938A1
• Time in Patent Office: 438 Days
• 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 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose

Abstract

Correction for initial variation in thickness of a polymer layer and for changes in the coating thickness that occur after implantation of a biosensor and therefore provides substantial increase in the accuracy and lifetime of implantable sensors is done using a factor derived from the decay of potential.

Claims

1. An implantable electrochemical sensor system comprising:

a biosensor comprising an electrode and a polymer layer having a thickness and containing an enzyme;

a source configured to apply a potential (V) to the biosensor, said potential being sufficient to oxidize or reduce a redox active species in the solution and generate a current;

a controller configured to control the source;

a potentiometer configured to collect potential measurements at a plurality of different times after application of potential ceases;

logic configured to determine the thickness of the polymer layer; and

an output device configured to communicate results determined by the logic.

2. The system of claim 1, wherein the redox active species is a part of a reversible redox couple and the thickness of the polymer layer is proportional to 1/k.

3. The system of claim 2, wherein the logic is further configured to determine a correction factor for the thickness of the polymer layer based on the slope (k) of a plot of V versus 1/√

t.

4. The system of claim 1, wherein the redox active species is part of an irreversible redox couple and the thickness of the polymer layer is proportional to 1/√

k.

5. The system of claim 4, wherein the logic is further configured to provide a corrected measure of analyte in the sample.

6. The system of claim 5, wherein the system further comprises an operational system component configured to receive one or more control parameters determined by the logic.

7. The system of claim 6, wherein the operational system component is an insulin pump.

8. The system of claim 6, wherein the operational system component is a cardiac stimulator.

9. The system of claim 1, wherein the electrode is platinum.

10. The system of claim 1, wherein the electrode is gold.

11. The system of claim 1, wherein, for a particular determination of analyte, the potential is applied to the biosensor for a period of 60 seconds or less.

12. The system of claim 11, wherein the potential is applied to the biosensor for a period of 40 seconds or less.

13. The system of claim 12, wherein the potential is applied to the biosensor for a period of 10 to 30 seconds.

14. The system of claim 11, wherein the potential measurements are collected during a period that is 5 seconds or less after switching off the applied potential.

15. The system of claim 14, wherein the potential measurements are collected during a period of time that is 2 seconds or less after switching off the applied potential.

16. The system of claim 1, wherein the system further comprises an operational system component configured to receive one or more control parameters determined by the logic.

17. The system of claim 16, where the operational system component is an insulin pump.

18. The system of claim 16, wherein the operational system component is a cardiac stimulator.

19. An implantable electrochemical sensor system comprising:

a biosensor comprising an electrode and a polymer layer having a thickness and containing an enzyme;

a source configured to apply a potential (V) to the biosensor, said potential being sufficient to oxidize or reduce a redox active species in the solution and generate a current;

a controller configured to control the source;

a potentiometer configured to collect potential measurements at a plurality of different times after application of potential ceases;

logic configured to determine the thickness of the polymer layer;

an output device configured to communicate results determined by the logic; and

an operational system component configured to receive one or more control parameters configured by the logic.

20. The system according to claim 19, wherein the logic is further configured to determine a measure of analyte that is corrected based on the determination of the thickness of the polymer layer.