By this technique, the w x insulatorrelectrolyte interface remains simple and totally
blocking, its potential is determined by surface complexation reaction which can be modeled by the site-binding
model as pH sensitivity 3 . This principle insures a low w x response time and a long lifetime for this simple ISFET
structure, and moreover, there is no indefinite interfacial potential as it is the case for polymeric membranerinsulator
interface 4 . The drawback of the grafting process is that the chemical species are not commercially available,
and a heavy work of chemical synthesis has to be done.
The responses of the grafted ISFETs are sub-nernstian, due
to the low density of grafted sites 5,6 . w x