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

Improving the performance of electrochemical sensors based on indium tin oxide (ITO) can be achieved via intrinsically conducting polymers such as poly (3, 4 ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS). However micropatterning of PEDOT:PSS to form microelectrodes on such substrates has been challenging. Here we demonstrate a technique for the precise micropatterning of a conductive ink on ITO 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 impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. A sensitive sensor is fabricated for the neurotransmitter dopamine, with a linear range from 1 to 50 μM. The sensor signal is very stable under cyclic increase and decrease in the concentration of dopamine. This sensing can be achieved even in the presence of ascorbic acid at 1000 times higher concentration than dopamine. Further, enzymes can be immobilized in the conductive matrix to form highly selective sensors. Such robust micropatterning strategies can greatly expand the use of conducting polymer substrates in biosensing applications.