A Microelectrochemical Enzyme Transistor Based on an N-Alkylated Poly(Aniline) and Its Application to Determine Hydrogen Peroxide at Neutral pH

Conducting polymers are important materials for several applications, among them, newly developed sensors that are based on changes in the conductivity of polyaniline (PANI). These sensors usually have pH limitations related to PANI characteristics (need for positive charge on the nitrogen atoms to get high conductivities). In this work, we report on a simple and fast treatment with propane sultone to dramatically improve PANI conductivity at neutral pH. As a result of this treatment, conductivity of the partially sultonated PANI (PSPANI) keeps its high conductivity at low pH almost unchanged, and as the pH approaches neutrality, PSPANI remains remarkably conductive (resistance grows less than 10 fold), while resistance in PANI increases up to 6 orders of magnitude. Electrochemical techniques and X-ray photoelectron spectroscopy are used to study the reaction. An application of this treatment to a hydrogen peroxide sensor is presented. Detection of <1 ppm at neutral pH could be achieved.