High conductive, mechanical properties and temperature-sensitive alginate-based hydrogel enhanced with tunicate...

Conductive hydrogels (CHs) have garnered significant interest as promising candidates for flexible wearable electronics, offering alternatives to conventional rigid metal-based sensors. However, existing CHs often suffer from compromised mechanical integrity, limited conductivity, inadequate thermoresponsiveness, and functional singularity. Herein, a multifunctional hydrogel with exceptional conductivity, mechanical robustness, and temperature sensitivity was engineered via free-radical polymerization of N-isopropylacrylamide (NIPAM) within a sodium alginate (SA) matrix reinforced with tunicate cellulose nanocrystals (TCNCs), followed by ionic crosslinking in calcium chloride (CaCl₂) solution. The resultant hydrogel demonstrated remarkable mechanical properties (tensile strength: 152.4 kPa, elongation at break: 626.9 %), high conductivity (13.9 S/m), strain-sensitive behavior (gauge factor [GF] = 0.96 for 50-100 % strain, GF = 1.56 for 100-200 %, GF = 2.50 for 200-300 %), and pronounced thermoresponsiveness (temperature coefficient of resistance [TCR] = -7.0643 %/°C for 25-30 °C, TCR = 3.7569 %/°C for 30-40 °C, TCR = 1.3776 %/°C for 40-50 °C). These attributes stem from synergistic physical-chemical crosslinking networks, enabling real-time monitoring of human motion and temperature fluctuations. This work advances the design of high-performance CHs for next-generation wearable sensing technologies.