The theory concerning conventional membrane electrodes is often used as a starting point for the theoretical description of the operation of an ion-sensitive field-effect transistor. Although this results in a useful description of the device, a better view of the principles, and consequently the possibilities, of the new ion-sensitive device may result if the analysis is carried out in more detail, especially with respect to measuring concepts. This is presented in the paper. A careful comparison between the operation of a conventional membrane electrode and the i.s.f.e.t. leads to a definite classification of different types of i.s.f.e.t.s. These types are illustrated with corresponding measurements. In addition, the most appropriate application for each type is mentioned.
Bergveld, P., & de Rooij, N. F. (1979). From conventional membrane electrodes to ion-sensitive field-effect transistors. Medical & biological engineering & computing, 17(5), 647-654. https://doi.org/10.1007/BF02440911