POTENTIAL RELAXATION AS A MEASUREMENT PROCEDURE FOR BIOSENSORS

Abstract

We present a discontinuously working procedure for long-term measurement of the concentration of an analyte in a solution with an enzyme electrode. As compared with this method the well-known amperometric procedure works continuously: The working electrode is permanently forced to a certain voltage, and a current results, the magnitude of which is a measure of the concentration of the analyte. The disadvantage may arise that the function of the working electrode can be affected by products of interfering reactions and succeeding reactions (e.g. polymerization). In in-vivo- application the permanently applied voltage at such electrodes can also cause electrochemical conversion of physiological substances into toxic ones and stimulate immune reactions leading to encapsulating of the sensor. The presented relaxation procedure uses the same biosensor arrangement as the amperometric one. The respective voltages, however, are applied only for a short time (about one second) and the interruptions are long (in the range of minutes).