RESUMO
Hydrogels are attractive, active materials for various e-skin devices based on their unique functionalities such as flexibility and biocompatibility. Still, e-skin devices are generally limited to simple structures, and the realization of optimal-shaped 3D e-skin devices for target applications is an intriguing issue of interest. Furthermore, hydrogels intrinsically suffer from drying and freezing issues in operational capability for practical applications. Herein, 3D artificial skin devices are demonstrated with highly improved device stability. The devices are fabricated in a target-oriented 3D structure by extrusion-based 3D printing, spontaneously heal mechanical damage, and enable stable device operation over time and under freezing conditions. Based on the material design to improve drying and freezing resistance, an organohydrogel, prepared by solvent displacement of hydrogel with ethylene glycol for 3 h, exhibits excellent drying resistance over 1000 h and improved freezing resistance by showing no phase transition down to -60 °C while maintaining its self-healing functionality. Based on the improved drying and freezing resistance, artificial skin devices in target-oriented optimal 3D structures are presented, which enable accurate positioning of touchpoints even on a complicated 3D structure stably over time and excellent operation at temperatures below 0 °C without losing their flexibility.
