Wide-Humidity Applicable, Anti-Freezing and Healable Zwitterionic Hydrogels for Ion-Leakage-Free Iontronic Sensors.

Hydrogels have entered the spotlight for applications in soft electronic devices and machines. It is essential and challenging to obtain hydrogels that can function properly under varying environmental circumstances, i.e., 30%-90% relative humidity (RH) and -20-40°C due to their intrinsic nature to lose and absorb water upon variations in humidity and temperature. In this work, a green solvent, solketal, is introduced into poly 3-dimethyl-2-(2-methylprop-2-enoyloxy)ethyl azaniumyl propane-1-sulfonate (poly(DMAPS)) zwitterionic hydrogels. Compare to the commonly-used glycerol, solketal endows hydrogels with greater possibility for further modification as well as improved water content and mechanical performance consistency over 30%-90% RH. Encouragingly, the optimized hydrogel demonstrates its unique merits as a dielectric layer in iontronic sensors, featuring non-leaky ions, high sensitivity (1100 kPa -1 ), wide humidity and temperature applicability. A wide-humidity healable and stretchable electrode is attained by combining the hydrogel substrate with Ag@poly(DMAPS) paste. Integrating the high-performance electrode and dielectric layer, a full-device healable and highly-sensitive sensor is developed. This study is a pioneering work that tackles the broad humidity applicability issue of hydrogel materials, and demonstrates the ion-leakage-free ionic skins with zwitterionic dielectrics. We believe, the outcomes of the study will considerably promote advancements in the fields of hydrogel electronics and iontronic sensors. This article is protected by copyright. All rights reserved.