Ta205-pH-ISFET: A BASIC STRUCTURAL ELEMENT FOR BIOSENSOR APPLICATIONS

Abstract

The wide range of ion-sensitive layers, be they inorganic or organic, that can be employed for the use with ion-sensitive field-effect transistors (ISFETs) , brings to mind the production of a BASIC STRUCTURAL ELEMENT (1). After adjusting to the requirements of MOS-technology, one produces ISFETs containing all layers up to the last ion-sensitive layer; here the basic structural element may already be sensitive to one type of ion as is the case with the pH-sensitive Tag0s5-layer. Then, as a final step in the process, the special sensitive layer e.g. containing organic ion exchangers or enzymes can be applied by the ultimate user himself. Moreover this procedure allows older, used layers which no longer respond reliably and reproducably to be removed and replaced by a fresh layer. Of course this procedure presupposes a thorough knowledge of the properties of the layer systems, as regards their stability and reproducibility.