Eutectogel Electrodes with Self-powered Capability for Flexible Electrophysiological Sensor

Conductive hydrogels possess remarkable advantages when employed as electrode materials for triboelectric nanogenerator (TENG)-based sensing applications. Nevertheless, hydrogel electrodes suffer from critical limitations under low-temperature environments, including increased brittleness and inferior self-healing capability, as well as conductivity degradation caused by the crystallization of free water within the gel matrix. To address these challenges, we developed a eutectogel electrode via rational design of a ternary polymerizable deep eutectic solvent, incorporating chitosan as a reinforcing and conductive secondary network, and integrating extensive hydrogen bonding interactions. The optimized eutectogel (CPD) exhibited a toughness of 0.25 MJ m-3, a conductivity of 0.25 mS cm-1, and rapid self-healing ability. Notably, it retained 92% of its room-temperature conductivity, and its mechanical properties remained nearly unchanged at -80 °C. The assembled CPD-TENG generated an open-circuit voltage of 1.3 V in a single electrode mode at room temperature and maintained 1.2 V at -80 °C, which significantly surpassed the low-temperature stability of conventional hydrogel-based TENGs. Moreover, the CPD-TENG-based sensor with self-powered capacity could precisely monitor joint movements, facial expressions, and human locomotion at both room temperature and -20 °C. Overall, this work provides a feasible strategy for developing reliable self-powered sensors for extreme low-temperature applications.