Development of an ammonium ISFET sensor with a polymeric membrane including zeolite

This paper presents a first report on an ammonium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including a zeolite selective for ammonium exchange: clinoptilolite. The effect of zeolite content on sensitivity of detection is studied; an optimum is obtained for 43 w/w%. A sensitivity of detection of 32 mV/pNH4+ and a detection limit of 10−8 M are obtained. A highly selective ammonium ISFET is obtained.