Hydroquinone monosulfonate-doped polypyrrole electrodeposited on very low cost commercial junction field effect transistors as a novel ion sensitive field effect transistor pH sensor

Abstract

In this study, for the first time, we introduce a simple and low cost pH sensor based on a commercial junction field effect transistor. The transistor was mechanically treated, isolated and used as an ion sensitive field effect transistor for pH detection, after electrodeposition of the sensing membrane on its surface. Polypyrrole, as a suitable sensing membrane, was electrodeposited on the copper metal gate of transistor from a solution containing pyrrole monomer, hydroquinone monosulfonate as a proper ligand and sodium salicylate for avoiding the substrate oxidation, under a two-step deposition conditions. The prepared sensor showed a near-Nernstian response of 52.3 mV pH−1 over a linear pH range of 2.75–12.20, an ultra low hysteresis of 0.56 mV, a very low drift of 0.14 mV h−1 and a low response time of less than 8 s.