Potassium-selective conductometric sensor

Potassium-selective membranes known as sensing modules for potentiometric ion-selective electrodes are studied in ac-impedance mode. It is shown that the bulk resistance of thin (20–250 μm) membranes depends on the composition of aqueous bathing solution. The results are explained in terms of surface conductivity in space-charge region, in the vicinity of water microdroplets in membranes. A planar potassium-selective sensor with a conductometric signal is proposed.