Freezing-Tolerant and Stretchable Organohydrogels for Triboelectric Nanogenerators and Strain Sensors

Abstract

The rapid advancement of wearable electronics necessitates the development of flexible, durable, and environmentally stable energy and sensing materials. However, conventional hydrogels often suffer from poor mechanical robustness, rapid dehydration, and freezing at subzero temperatures, severely limiting their practical applications. In this work, we fabricate highly stretchable and antifreezing PVA/PAM/NaCl (PPN) organohydrogels by integrating a double-network structure with NaCl doping and glycerol treatment. The resulting PPN organohydrogels exhibit exceptional stretchability (2320%), high ionic conductivity (5.5 S/m), and remarkable long-term environmental stability (only 12% mass loss after 30 days). Furthermore, it maintains excellent mechanical and electrical performance at −20 °C, effectively suppressing ice formation. We demonstrate its versatility by utilizing the PPN organohydrogel in two key applications: (1) as a strain sensor with an ultrahigh gauge factor (GF = 26.608) for monitoring human motion, including subtle pulse signals; (2) as the electrode in a triboelectric nanogenerator (VMO-TENG), achieving a maximum power density of 0.5 W/m2. Moreover, by integrating the sensor with a genetic algorithm-optimized backpropagation neural network (GABP), we realize a high-accuracy gesture recognition system. This study provides a facile strategy for developing robust flexible electronics suitable for extreme environments and intelligent human–machine interaction.