Thin film hydrophilic electroactive polymer coatings for bioelectrodes

Hybrids of conducting polymers (CPs) and hydrogels have been explored as soft electroactive coatings for improving the mechanical and electrical performance of metallic implant electrodes. However, hydrogel fabrication methods pose a significant challenge to producing thin (sub-micron) coatings, resulting in bulky implants, which displace a large volume of tissue. To address this issue, polymer brushes of poly(2-hydroxyethyl methacrylate) (pHEMA) were covalently bound to a gold electrode using surface initiated atom-transfer radical-polymerization (SI-ATRP). The CP poly(3,4-ethylene dioxythiophene) (PEDOT) was electropolymersied through the brush layer to form a thin hydrophilic coating. The electrical properties of the hybrid were shown to be superior to homogenous CPs and the surface chemistry was varied as a function of PEDOT deposition time to present a graded composition of pHEMA and PEDOT. The resulting material was shown to support the attachment and differentiation of model neural cells, signifying the potential of these hybrid coatings for bioelectrode applications.