Electrical contacts to solid state ion-selective electrodes

Summary form only given. Solid-state microelectronic ion selective electrodes (ISEs) take the form of the ion selective field effect transistor (ISFET), the extended gate ion selective field effect transistor, or hybrid structures fabricated by a combination of thin- and thick-film technologies. The electrochemical processes which take place at the interface between the ion selective material (ISM) and the metal (or semiconductor) contact are crucial to the operation of any of these devices. Two different concepts are distinguished: where the ion selective material (ISM) is an ionic conductor, and where the ISM is an electronic conductor or has, at least, a significant electronic contribution to its conductivity. The author is concerned mainly with the first and more common case but mention is also made of electronically conducting materials as the basis of solid-state ISEs