Ultrasensitive and Stretchable Temperature Sensors Based on Thermally Stable and Self-Healing Organohydrogels.

Abstract

It is essential to impart the thermal stability, high sensitivity, self-healing, and transparent attributes to the emerging wearable and stretchable electronics. Here, a facile solvent replacement strategy is exploited to introduce ethylene glycol/glycerol (Gly) in hydrogels for enhancing their thermal sensitivity and stability synchronously. For the first time, we find that the solvent plays a key role in the thermal sensitivity of hydrogels. By adjusting the water content in hydrogels using a simple dehydration treatment, the thermal sensitivity is raised to 13.1%/°C. Thanks to the ionic transport property and water-Gly binary solvent, the organohydrogel achieves an unprecedented thermal sensitivity of 19.6%/°C, which is much higher than those of previously reported stretchable thermistors. The mechanism for the thermal response is revealed by considering the thermally activated ion mobility and dissociation. The stretchable thermistors are conformally attached on curved surfaces for the practical monitoring of minute temperature change. Notably, the uncovered Gly-organohydrogel avoids drying and freezing at 70 and -18 °C, respectively, reflecting the excellent antidrying and antifreezing attributes. In addition, the organohydrogel displays ultrahigh stretchability (1103% strain), self-healing ability, and high transparency. This work sheds light on fabricating ultrasensitive and stretchable temperature sensors with excellent thermal stability by modulating the solvent of hydrogels.