Selectivity enhancement in neutral-carrier-type ion sensors based on a liquid-crystalline polymer

Abstract

A liquid-crystalline polymer was applied to a neutral-carrier-type ion sensor as a membrane material for enhancement of ion selectivity. An ion-sensitive field-effect transistor (ISFET) based on the membranes containing the polymer showed high sensitivity and selectivity for K+ by adding a low-molecular-weight liquid crystal as the plasticizer. The ion-sensor properties of the ISFETs based on the membranes containing a liquid-crystalline polymer were similar to those of the corresponding ion-selective electrodes (ISEs) based on the same polymer. The ion sensor with a liquid-crystalline polymer was more durable than that without any liquid-crystalline polymer. The use of liquid-crystalline polymer as the membrane material improves not only the ion-sensor properties but also the durability.