Bio-derived protein-based E-skin: Ionic liquid-enhanced hydrogel sensors with high conductivity and biocompatibility

An MP-IL dual-network hydrogel sensor is developed from chicken by-products. • It offers skin-matched modulus, high conductivity, and wide-range dmotion monitoring. • The hydrogel shows high biocompatibility with no inflammatory response. • The hydrogel shows negligible IL leakage and stable 200-cycle performance. • This MP-based e-skin uniquely integrates biosafety and and biodegradability. Biocompatible sensors with tissue-like mechanical properties are urgently needed for individuals with communication and movement disorders. Conductive hydrogels are promising candidates, yet conventional synthetic versions face biosafety and degradability challenges for long-term wearable use. In this work, we developed a biocompatible dual-network hydrogel sensor for high-performance epidermal sensing, integrating the skin-homologous myofibrillar proteins (MP) with ionic liquid (IL) through unique molecular design. The hydrogel network is constructed via Schiff-base crosslinking between MP and oxidized dextran (ODex), interpenetrated with an ionically cross-linked sodium alginate (SA) network. This unique design achieves skin-matched mechanical properties (tensile strength 440.4 ± 16.6 kPa, elastic modulus 342.5 ± 12.2 kPa) and high ionic conductivity (9.1 mS/cm). The resulting sensor exhibits excellent strain response (0.4 s) and recovery (0.2 s) times, high sensitivity (gauge factor ~ 1.55), and stable resistance variation under both tensile and compressive deformation, showing potential for monitoring a wide range of motions from subtle physiological signals (e.g., frowning, swallowing, and smiling) to large-scale joint movements, speaking, and handwriting signal monitoring, with possible relevance to throat motion monitoring and assistive communication. The ionic liquid shows negligible leakage (<5% cumulative release over 7 days), and the hydrogel maintains stable mechanical performance over 200 cyclic loading-unloading tests, supporting long-term wearable reliability. In vitro cytotoxicity, in vivo skin patch, and implantation tests confirm excellent biocompatibility (cell viability ≥94.2%) with no significant inflammatory response. Sourced from low-cost chicken meat by-products, this hydrogel provides an alternative platform for next-generation epidermal electronics that harmonizes biosafety and biodegradability. Download: Download high-res image (160KB) Download: Download full-size image