Chemical and physical FET-based sensors or variations on an equation

This paper exposes the continuous thread of Bergveld's work: the model equation of the field-effect transistor (FET) derived and repeated in the theoretical section. Zooming in on some of the variables of this equation leads us to several of his important projects. A short description and typical results of these highlights are presented. At the end of this paper, two different operational concepts are abstracted from these projects and an outlook on possible new research is presented.