A Review of Biosensor and Industrial Applications of pH-ISFETs and an Evaluation of Honeywell’s “DuraFET”

Abstract Biosensors were viewed by earlier workers as possibly lucrative applications for ion selective field effect transistor (ISFET) technology. Such products have yet to find widespread use, however, for a number of reasons that will be reviewed in this article. Some have to do with the inherent nature of biosensor applications per se. For example, biocompatibility is an issue that must be faced regardless of the mechanism of transduction. Others have to do with the inherent nature of the sensor itself. Encapsulation of electronically sensitive parts can prove to be so problematical that lengthy timelines and costly overruns compromisecommercial promise. Intermediate applications, which will be referred to here as “industrial” appear to be commercially viable, however, and can be used to provide profits that will drive further development in the biosensor area. Such applications will also be reviewed. Finally, a specific application will be described in detail (exclusive of proprietary concerns), to illustrate the remarkable ruggedness, stability, and accuracy of a particular commercially available pH-ISFET – Honeywell’s “DuraFET”– a truly useful ion selective field effect transistor.