Development, Operation, and Application of the Ion-Sensitive Field-Effect Transistor as a Tool for Electrophysiology

A new solid-state device has been developed for the measurement of ion activities in electrochemical and biological environments. One can recognize in the device the properties of both a glass electrode and a field-effect transistor. This justifies the name ion-sensitive field-effect transistor. The device makes it possible to measure ion activities without using a reference electrode. For its application, a special electronic circuit is described. Results of measured Na+ and H+ ion activities are given in detail. As an example for electrophysiological application, results are shown of recorded extracellular ion pulses measured with a guinea pig taenia coli.