PEDOT as a high charge injection material for low-frequency stimulation

Alternating current stimulation (ACS) provides a versatile tool for modulating brain activity and presents a promising strategy for the treatment of neurological disorders like Parkinson's disease or epilepsy. Stimulation of neural tissue at low-frequency however poses new challenges on conventional electrode materials which support limited charge transfer in the desired frequency range, from less than 0.1 Hz to several tens of Hz. In our study we address this challenge by investigating the charge transfer properties of PEDOT/PSS coatings for low-frequency applications, focusing on the impact of the polymer bulk. PEDOT films of various thicknesses were exposed to low-frequency as well as DC stimulation in vitro and compared to Pt and IrOx electrodes as controls. The charge injection performance of the metallic substrates could be substantially improved already by a thin PEDOT coating. Additionally a linear dependency between charge injection and polymer thickness suggests that PEDOT coatings are promising as materials for future ACS applications.