Sweat-Enhanced Self-Adhesive Double-Network Hydrogel for Dynamic Skin Electrophysiology

• Published in: ACS materials letters Vol. 6; no. 11; pp. 4922 - 4931
• Main Authors: Liang, Huarun, Zhu, Mengjia, Li, Shuo, Wang, Haomin, Li, Donghang, Liang, Xiaoping, Lu, Haojie, Wu, Xun-En, Ma, Haoxuan, Liu, Nan, Zhang, Yingying
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.11.2024
• ISSN: 2639-4979; 2639-4979
• DOI: 10.1021/acsmaterialslett.4c01748

Electrophysiological monitoring is essential in healthcare and life sciences, yet conventional Ag/AgCl electrodes face challenges such as interfacial instability and motion artifacts. Herein, we propose a sweat-enhanced electrode design with a double-network hydrogel, comprising Ca2+-modified silk fibroin (SF) and poly­(acrylic acid) grafted with N-hydroxysuccinimide ester (PAA-NHS). The obtained biocomposite, SF-PAA-NHS (BioSP), exhibits strong skin adhesion through covalent cross-linking and intermolecular forces, achieving an interfacial toughness of 411 J m–2. Upon sweating, SF enhances adhesion by strengthening molecular mobility and mechanical interlocking, resulting in a nearly 23% increase in interfacial toughness. Additionally, sweat electrolytes boost BioSP’s ionic conductivity by about 45%, enhancing its electrophysiological monitoring capabilities. BioSP can also be combined with elastomers for excellent antidrying performance. Finally, high-fidelity and long-duration electrophysiological measurements validate the superior performance of the sweat-enhanced electrode, representing a significant advancement in skin electrode technology for reliable and durable monitoring on dynamic and sweaty tissue.