Self-Repairable Ionic Skin Based on Multiple Dynamic Bonds with Self-Adhesive, Anti-Freezing, and Antimicrobial Capabilities for Monitoring Human Motions

Abstract

Biomimetic ionic skins (i-skins) have received intensive attention because of their capabilities to emulate various functions of human skin. However, challenges still remain in developing i-skins with synergistic characteristics such as excellent mechanical properties, high strain sensitivity, freezing tolerance, and antimicrobial activity by a simple method. Herein, a hydrogel-based i-skin (P(AAc-co-CA)x) is facilely synthesized by one-pot free radical copolymerization of vinyl choline-asparagine ionic liquid (Cho-Asn VIL) and acrylic acid (AAc) monomers using Al3+ as a crosslinker and bacterial cellulose (BC) as reinforcing agent, respectively. The resultant hydrogels integrate multiple excellent performances, including skin-like modulus (100–300 KPa), superstretchability (2345 ± 97%), high self-healing efficiency (93.7 ± 4.6%), recovery ratio (139.3 ± 7%) and conductivity (1.28 ± 0.06 S m−1), as well as transparency, self-adhesiveness, antimicrobial activities, and biocompatible properties. Moreover, the i-skins based on P(AAc-co-CA) x hydrogels exhibit high sensitivity (gauge factor (GF) of 2.77), rapid response time (300 ± 15 ms), and excellent durability to both tensile and compressive deformation, and thus can be used to monitor and distinguish human motions. Significantly, P(AAc-co-CA) x hydrogels can still maintain notable mechanical property, conductivity, and sensibility even at −20 °C. These integrated multiple advantages make P(AAc-co-CA) x hydrogels highly promising in the fields of i-skins, flexible wearable sensors, and artificial intelligence.