A wet-resistant and low-temperature self-healing organohydrogel sensor towards direction-recognition and information transmission in extreme environments

Abstract

Flexible electronic devices based on hydrogels have attracted impressive attention. However, conventional hydrogels tend to suffer from swelling in aquatic environments and inevitably freeze under low-temperature conditions, resulting in the destruction and loss of their structure and performance. Thus, it is extremely necessary, but generally challenging, to create a wet-resistant and anti-freezing gel for maintaining excellent stability in various extreme environments. Herein, a multipurpose organohydrogel is constructed by a simple and rapid UV-initiated polymerization method. The introduced polyvinylpyrrolidone (PVP) effectively enhances the wet-resistant capability and self-healing property of as-prepared organohydrogel, and meanwhile, the dimethyl sulfoxide (DMSO)/H₂O binary solvent system endows the organohydrogel with superior low-temperature tolerance. Furthermore, the organohydrogel-based strain sensor can be used as a long-term wet-resistant flexible sensing device to precisely track various stretching deformations and complex human movements in water, pH 2.3 and pH 9 liquid media and exhibits a very attractive feature in distinguishing the direction of underwater movements. In addition, the resulting organohydrogel can withstand significant mechanical damage even in extremely cold environments of −40 °C. At the same time, after being stored at −40 °C for 15 days, the healed organohydrogel sensor is still capable of reliably recognizing the bending motion of a prosthetic finger at −40 °C. Impressively, based on the Morse code expression, the organohydrogel sensor can also serve as a low-temperature tolerant communication device for delivering various useful messages to the receiver in harsh climates. It is believed that this study offers a promising prospect for developing flexible electronics with multi-environmental stability.