AMPEROMETRIC MICROSENSOR FOR WATER

A thin film of a perfluorosulfonate lonomer (PFSI) is supported upon two electrodes. The positive electrode is composed of a noble metal. The polymer film has high affinity for water and certain other highly polar molecules, notably alcohols. When a voltage above the threshold of electrolytic breakdown potential of such a compound is applied across the film, the compound partitioned Into the film can be electrolytically decomposed. Provided that the electrolytic breakdown products have a high enough vapor pressure to spontaneously leave the film, a versatile sensor, with a current output related to the analyte concentration, is formed. Sensors fabricated from available PFSI materials and functioning in this manner behave essentially as sensors specific for water and the lower alcohols. © 1990, American Chemical Society. All rights reserved.