A Solid-State Reference Electrode Based on Bilayer Coating with Poly(p,p′-biphenol) and Polyimide Films for the Gate of Field Effect Transistor

Abstract

A solid-state reference electrode has been fabricated. Its design is based on a field effect transistor, the gate of which is coated with two kinds of polymeric films in a bilayer state: the inner layer is an electroactive electropolymerized poly(p,p’-biphenol) film and the outer one is a polyimide film. The electrode characteristics have been examined. The bilayer film-coated reference field effect transistors (RFETs) thus fabricated were insensitive to electrolyte ions (including H+ and OH-) under the condition of a constant concentration (e.g., 0.1 M) of an electrolyte; thus they could function as a reference electrode. These RFETs showed insensitivity to Oj and less sensitivity to CO2 (compared with the RFET coated with the polyimide film alone), long-term stability and little drift. The results demonstrate that the bilayer film-coated FETs are promising as a solid-state reference electrode coupled with conventional ion-sensitive field effect transistors in a biological system.