Stretchable Freezing-Tolerant Triboelectric Nanogenerator and Strain Sensor Based on Transparent, Long-Term Stable, and Highly Conductive Gelatin-Based Organohydrogel

Conductive hydrogels have attracted tremendous attention for the next-generation electronic/energy/robotic application owing to their excellent mechanical and electrical properties, including stretchability, high conductivity, and stability. How to simultaneously realize their highly transparent, self-healing, antifreezing/antidrying, biocompatible and highly conductive features through a simple approach is still a challenge. Herein, stretchable freezing-tolerant triboelectric nanogenerator (TENG) and strain sensor have been fabricated based on transparent, long-term stable, and highly conductive gelatin/NaCl organohydrogel (GNOH), which is prepared via a facile immersion strategy in a glycerol/water binary solvent. The GNOH demonstrates superior merits of strain (300%), transparency (85%), high conductivity (1.6 S/m), freezing tolerance (-20 ℃), self-healing capability (91%), and ambient stability (over 30 days). Furthermore, the wearable strain sensors enable the detecting, quantifying, and monitoring of human activities with high sensitivity of about 2.5 (strain of 0~200%). Meanwhile, the fabricated TENG in single-electrode mode can achieve an excellent electrical outputs to power portable electronics when efficiently harvesting biomechanical energies, even at harsh cold temperature (-20 ℃). Additionally, a flexible self-powered calculator based on the arrayed TENG as touch panel is also explored for human-machine interaction (HMI). This study paves the way for potential applications in wearable electronics, healthcare monitoring, biomechanical energy harvesting and HMI.