One Pot Photomediated Formation of Electrically Conductive Hydrogels

Abstract

Electrically conductive hydrogels represent an innovative platform for the development of bioelectronic devices. While photolithography technologies have enabled the fabrication of complex architectures with high resolution, photoprinting conductive hydrogels is still a challenging task because the conductive polymer absorbs light which can outcompete photopolymerization of the insulating scaffold. In this study, we introduce an approach to synthesizing conductive hydrogels in one step. Our approach combines the simultaneous photo-crosslinking of a polymeric scaffold and the polymerization of 3,4ethylene dioxythiophene (EDOT), without additional photocatalysts. This process involves the copolymerization of photocross-linkable coumarin-containing monomers with sodium styrenesulfonate to produce a water-soluble poly(styrenesulfonate-co-coumarin acrylate) (P(SS-co-CoumAc)) copolymer. Our findings reveal that optimizing the [SS]:[CoumAc] ratio at 100:5 results in hydrogels with the strain at break up to 16%. This mechanical resilience is coupled with an electronic conductivity of 9.2 S m −1 suitable for wearable electronics. Furthermore, the conductive hydrogels can be photopatterned to achieve micrometer-sized structures with high resolution. The photo-cross-linked hydrogels are used as electrodes to record stable and reliable surface electromyography (sEMG) signals. These novel photo-cross-linkable polymers combined with one-pot PEDOT (poly-EDOT) polymerization open possibilities for rapidly prototyping complex bioelectronic devices and creating custom-designed interfaces between electronics and biological systems.

Photography-Inspired Patterned Vapor Phase Polymerization of Conductive PEDOT on Rigid and Stretchable Substrates

“…The third set of methods incorporates additives into suspensions of PEDOT that form cross-linked networks upon UV light exposure. − These methods typically present the smallest trade-offs, with some achieving high conductivity, and others remarkable stretchability. However, the best methods require the use of advanced synthetic techniques that may be out of reach for many users.…”