Freestanding, soft bioelectronics

Soft, flexible electrode arrays are proposed to address the limitations of metallic tracks and electrodes in stimulating neuroprosthetics. The aim of these studies was to explore spatially selective polymerization of conductive polymer (CP) within a hydrogel as a proof of concept for freestanding conductive hydrogel electrode arrays, which are not bound to a metallic substrate. A suspension of CP chains within a non-conductive hydrogel was used to initiate subsequent electrochemical growth of highly conductive dense CP in patterned locations throughout the hydrogel volume. Tracks were produced and electroactivity was confirmed through an increase in charge storage capacity and a decrease in impedance. The electrochemical growth of poly(ethylene dioxythiophene) (PEDOT) was established visually and found to be constrained to the hydrogel track. Excitable cells, HL-1s were cultured on the hydrogel construct and found to attach and proliferate. Conductive hydrogels may provide an alternative to metals for producing soft bioelectronics.