Advances in chemical sensors, biosensors and microsystems based on ion- sensitive field-effect transistor

Introduced as a tool for electrophysiology three and a half decades ago, the ion-sensitive field-effect transistor (ISFET) is a generic electrochemical structure offering a family of analytical devices for applications in agriculture, food processing, medical diagnostics, pharmaceuticals, paper, pulp and chemical industries, and environmental control. Besides its use as a chemical sensor, this device has also served as the electrical transduction element for many enzyme and immunological biosensors. This paper presents the current status of this microelectronic device in terms of the theoretical understanding of its operational mechanism, the techniques used for its fabrication and the measurement circuits used in instrumentation. The state of the art of ISFET as a chemical and biosensor is examined, major problems in this area are discussed, perspectives of recent interesting developments are described and future research directions are indicated. Highlights of the work done on ISFET at our institute are presented.