Biosensing using photolithographically micropatterned electrodes of PEDOT:PSS on ITO substrates

Abstract

Improving the performance of electrochemical sensors based on indium tin oxide (ITO) can be achievedvia intrinsically conducting polymers such as poly (3, 4 ethylenedioxythiophene): polystyrene sulfonate(PEDOT:PSS). However micropatterning of PEDOT:PSS to form microelectrodes on such substrates hasbeen challenging. Here we demonstrate a technique for the precise micropatterning of a conductive ink onITO using photolithography to realize a covalently-attached ion-transport matrix for stable biosensing.This micropatterning is accomplished using an all water-based and ambient temperature processing.We present electrochemical characterization of the material composite via electrochemical impedancespectroscopy, cyclic voltammetry and differential pulse voltammetry. A sensitive sensor is fabricated forthe neurotransmitter dopamine, with a linear range from 1 to 50 M. The sensor signal is very stableunder cyclic increase and decrease in the concentration of dopamine. This sensing can be achieved evenin the presence of ascorbic acid at 1000 times higher concentration than dopamine. Further, enzymes canbe immobilized in the conductive matrix to form highly selective sensors. Such robust micropatterningstrategies can greatly expand the use of conducting polymer substrates in biosensing applications.