Eutectogel-based self-powered wearable sensor for health monitoring in harsh environments

Triboelectric nanogenerators (TENG) have emerged as a highly promising energy harvesting technology, attracting significant attention in recent years for their broad applications. Gel-based TENGs, with superior stretchability and sensitivity, have been widely reported as wearable sensors. However, the traditional hydrogel-based TENGs suffer from freezing at low temperatures and drying at high temperatures, resulting in malfunctions. In this study, we introduce an anti-freezing eutectogel, which uses a deep eutectic solvent (DES), to improve the stability and electrical conductivity of TENGs in harsh environmental conditions. The eutectogel-based TENG (E-TENG) produces an open-circuit voltage of 776 V, a short-circuit current of 1.54 µA, and a maximum peak power of 1.1 mW. Moreover, the E-TENG exhibits exceptional mechanical properties with an elongation at a break of 476% under tension. Importantly, it maintains impressive performances across a wide temperature range from −18 to 60 °C, with conductivities of 2.15 S/m at −10 °C and 1.75 S/m at −18 °C. Based on the excellent weight stability of the E-TENG sensor, motion sensing can be achieved in the air, and even underwater. Finally, the versatility of the E-TENG can serve as a wearable sensor, by integrating it with Bluetooth technology. The self-powered E-TENG can monitor various human motion signals in realtime and send the health signals directly to mobile phones. This research paves a new road for the applications of TENGs in harsh environments, offering wireless flexible sensors with real-time health signal monitoring capabilities.