Correlation between the electrical charge properties of polymeric membranes and the characteristics of ion field effect transistors or penicillinase based enzymatic field effect transistors

In this paper, the influence of the electrical charge properties of polymeric membranes on the characteristics of ion sensitive field effect transistors (ISFETs) and penicillinase based enzymatic field effect transistors (ENFETs) was investigated. It was first shown that the pH-response of an ISFET is influenced by the nature of the polymeric membranes [poly(acrylamide) gel (PAAG), bovine serum albumin (BSA), Nafion, poly-4-vinyl pyridine (PVP)] deposited on the gate surface, especially at low ionic strength. This phenomenon can be explained by the presence in the membrane of charges, depending on the pH value of the electrolyte. Calibration tests were also performed on a penicillinase based ENFET in order to study the influence of the charge of the BSA polymeric membrane containing the enzyme. Conditions for an analysis with minimal influence of the membrane charge on the ENFET response are proposed.