Micromachined ion-selective electrodes with polymer matrix membranes

Abstract

We have developed a new method for the integration of ion-sensitive membranes and silicon sensor chips. The ion-sensitive membrane is deposited in pyramidal containments produced on silicon by an anisotropic etching technique. Here we demonstrate the application of this method to the development of nitrate-sensitive sensors. PVC membranes are cast into the membrane containment. The sensors show an improved mechanical stability and lifetime compared to ISFET's. Slopes, detection limits and selectivities of the containment sensors are similar to those of ion-selective electrodes with internal electrolyte solution using the same membrane composition. The results of the drift and hysteresis measurements are sufficiently good for most practical applications.