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 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.