Implantable Electrochemical Biosensor System and Method
First Claim
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1. A method for determination of the thickness of a polymer layer in an implantable biosensor comprising an electrode and the polymer layer, wherein the polymer layer contains an enzyme, said method comprising the steps of:
- (a) placing the biosensor in contact with a solution;
(b) applying a potential to the biosensor sufficient to oxidize or reduce a redox active species in the solution and generate a current,(c) switching off the applied potential and observing subsequent decay of potential to obtain a plurality of V versus t data points, and(d) determining the slope k of a plot of V versus 1/sqrt-t, wherein the slope k provides an indication of the thickness of the polymer layer.
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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.
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Citations
23 Claims
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1. A method for determination of the thickness of a polymer layer in an implantable biosensor comprising an electrode and the polymer layer, wherein the polymer layer contains an enzyme, said method comprising the steps of:
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(a) placing the biosensor in contact with a solution; (b) applying a potential to the biosensor sufficient to oxidize or reduce a redox active species in the solution and generate a current, (c) switching off the applied potential and observing subsequent decay of potential to obtain a plurality of V versus t data points, and (d) determining the slope k of a plot of V versus 1/sqrt-t, wherein the slope k provides an indication of the thickness of the polymer layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for determining an analyte in a sample, comprising the steps of
(a) placing a sample to be tested for analyte in contact with a biosensor comprising an electrode and a polymer layer containing an enzyme, (b) applying a potential to the biosensor sufficient to oxidize or reduce a redox active species and generate a current, (c) switching off the applied potential and observing subsequent decay of potential to obtain a plurality of V versus t data points, (d) determining the slope k of a plot of V versus 1/sqrt-t, (e) determining a correction factor for the thickness of the polymer layer from the slope k, (f) determining an uncorrected measure of analyte in the sample, (h) correcting the uncorrected measure of analyte using the correction factor to provide a corrected measure of analyte, and
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23. An implantable electrochemical sensor system comprising:
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an electrode and a polymer layer containing an enzyme, a controller for first applying a potential to the electrode and then switching off the applied potential, a potentiometer that measures a plurality of V versus time data points after the switching off of the applied potential, and a data processor that determines the slope k of a plot of the V versus time data points.
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Specification