Patent ID: 6447670
Filing Date: 2002-09-10
Classification: A61N,G01N

Abstract:
A method for making an electrochemical measurement of a concentration of at least one chemical entity dissolved in a liquid medium, comprising the steps of:immersing only a counter electrode, a working electrode and a reference electrode in a liquid medium in which at least one chemical entity is dissolved; applying a measurement potential to the working electrode relative to the reference electrode, corresponding to a measurement voltage during at least a portion of a measurement period, and thereby causing said chemical entity to participate in an electrochemical reaction at the working electrode, said electrochemical reaction resulting in a measurement evoked current; measuring said measurement evoked current; comparing said measurement evoked current with a predetermined value; and compensating for potential drift at said reference electrode by changing said measurement voltage in incremental steps to cause said measurement current to approach said predetermined value, and after each increment of said measurement voltage, comparing a resulting measurement evoked current with said predetermined value, and continuing incrementally changing said measurement potential until said measurement evoked current is substantially equal to said predetermined value.