Temperature-Responsive Cellulose-Based Janus Hydrogel as Underwater Electronic Skin

This study develops a Janus-structured hydrogel sensor (P(AA-<i>co</i>-PNIPAM/CDs)) through template-assisted copolymerization of acrylic acid and <i>N</i>-isopropylacrylamide with dopamine-cellulose carbon dots (CDs). The hydrogel demonstrates temperature-responsive strain sensing regulation and enhanced interfacial adhesion, achieving remarkable peel strengths of 237.8 N m^-1 (air, 25 °C) and 42.7 N m^-1 (water, 50 °C). CD incorporation improves conductivity (1.219 mS cm^-1) while reinforcing dynamic adhesion through hydrogen bonding and π-π interactions. The dual-responsive hydrogel exhibits exceptional joint motion monitoring capabilities across diverse environments, maintaining a stable electrical signal output during repetitive stretching (100% strain). Its temperature-modulated underwater adhesion and strain-sensitive conductivity enable the precise detection of both macroscopic movements (joint flexion) and subtle physiological signals (pulse waves). These synergistic properties position P(AA-<i>co</i>-PNIPAM/CDs) as a promising candidate for next-generation smart sensors in athletic monitoring and aquatic robotics, particularly in addressing challenges in underwater wearable electronics and adaptive human-machine interfaces.