One Pot Photomediated Formation of Electrically Conductive Hydrogels

Dan My Nguyen; Chun-Yuan Lo; Tianzheng Guo; Taewook Choi; Shalini Sundar; Zachary Swain; Yuhang Wu; Charles Dhong; Laure V Kayser

doi:10.1021/acspolymersau.3c00031

One Pot Photomediated Formation of Electrically Conductive Hydrogels

ACS Polym Au. 2023 Dec 8;4(1):34-44. doi: 10.1021/acspolymersau.3c00031. eCollection 2024 Feb 14.

Authors

Dan My Nguyen¹, Chun-Yuan Lo¹, Tianzheng Guo², Taewook Choi¹, Shalini Sundar³, Zachary Swain², Yuhang Wu², Charles Dhong^{2

3}, Laure V Kayser^{1

2}

Affiliations

¹ Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
² Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States.
³ Department of Biomedical Engineering, University of Delaware, Newark, Delaware 19716, United States.

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-cross-linking of a polymeric scaffold and the polymerization of 3,4-ethylene dioxythiophene (EDOT), without additional photocatalysts. This process involves the copolymerization of photo-cross-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.