Implantable electrochemical biosensor system and method

• US 9,907,501 B2
• Filed: 03/14/2016
• Issued: 03/06/2018
• 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 YONGKYUN
• Application Number:
  US15/069,071
• Publication Number:
  US 20160192871A1
• Time in Patent Office: 722 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 containing an enzyme;

a controller for first applying a potential (V) to the biosensor when the biosensor is in contact with a solution, wherein the applied potential is sufficient to oxidize or reduce a redox active species in the solution and generate a current, and then switching off the applied potential;

a potentiometer that measures a plurality of V versus time (t) data points after the switching off of the applied potential; and

a data processor that determines the slope (k) of a plot of V versus 1/√

t, and provides an indication of the thickness of the polymer layer of the biosensor based on the determined slope.

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

3. 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.

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

5. The system claim 1, wherein the electrode is gold.

6. 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.

7. The system of claim 6, wherein the potential is applied to the biosensor for a period of 40 seconds or less.

8. The system of claim 7, wherein the potential is applied to the biosensor for a period of 10 to 30 seconds.

9. The system of claim 6, wherein the V versus t data points are collected during a period of time that is 5 seconds or less after switching off of the applied potential.

10. The system of claim 9, wherein the V versus t data points are collected during a period of time that is 2 seconds or less after switching off of the applied potential.