Ultrasensitive\nand Stretchable Temperature Sensors\nBased on Thermally Stable and Self-Healing Organohydrogels

Abstract

It\nis essential to impart the thermal stability, high sensitivity,\nself-healing, and transparent attributes to the emerging wearable\nand stretchable electronics. Here, a facile solvent replacement strategy\nis exploited to introduce ethylene glycol/glycerol (Gly) in hydrogels\nfor enhancing their thermal sensitivity and stability synchronously.\nFor the first time, we find that the solvent plays a key role in the\nthermal sensitivity of hydrogels. By adjusting the water content in\nhydrogels using a simple dehydration treatment, the thermal sensitivity\nis raised to 13.1%/°C. Thanks to the ionic transport property\nand water–Gly binary solvent, the organohydrogel achieves an\nunprecedented thermal sensitivity of 19.6%/°C, which is much\nhigher than those of previously reported stretchable thermistors.\nThe mechanism for the thermal response is revealed by considering\nthe thermally activated ion mobility and dissociation. The stretchable\nthermistors are conformally attached on curved surfaces for the practical\nmonitoring of minute temperature change. Notably, the uncovered Gly-organohydrogel\navoids drying and freezing at 70 and −18 °C, respectively,\nreflecting the excellent antidrying and antifreezing attributes. In\naddition, the organohydrogel displays ultrahigh stretchability (1103%\nstrain), self-healing ability, and high transparency. This work sheds\nlight on fabricating ultrasensitive and stretchable temperature sensors\nwith excellent thermal stability by modulating the solvent of hydrogels.