Carbon capsules and g-C3N4 co-reinforced multifunctional PVA/PEO hydrogel with ultrastretchable, antifreezing, heat resistance and high sensitive strain

There has been extensive research on conductive hydrogels, however, the current lack of practical applications is a significant issue. The crucial challenge lies in effectively integrating conductive hydrogels into practical use. Here, a uniform multifunctional hydrogel was facilely fabricated by integrating nitrogen-doped carbon capsules (N-Cc) and g-C₃N₄ to PEO/PVA hydrogels (VECGNC). The introduction of a double network structure through carbon material endows the VECGNC hydrogel with exceptional mechanical strength (stress: 47.2 kPa; strain: 318 %) and high electrical conductivity (0.025 S cm⁻¹). And it showed a good linear relationship between the temperature and pressure difference. Taking advantage of these properties, a logic gate circuit capable of sensing external pressure changes and effecting corresponding adjustments was constructed. Moreover, the strain sensitivity hydrogel designed in this work is capable of intelligent new traffic lights. Our work offers novel insights and methodologies for the utilization of multifunctional hydrogels in multi-scenario temperature and strains ensing applications.