Implantable electrochemical biosensor system and method
View Patent ↗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.
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.