Squid-inspired photonic-ionic skin with anti-freezing, drying-tolerance, and antibacterial abilities for wirelessly interactive multi-sensing

Abstract

Squid skins can actively transduce complex environmental information into bioelectrical and color-change signals. Here, inspired by squid skins, we present a novel photonic-ionic skin (PIskin) capable of outputting electrical/optical signals synergistically, featuring anti-freezing, drying-tolerance and antibacterial abilities. The PIskin was developed by hierarchical self-assembly strategy of antibacterial glycerol monolaurate (GML) in a poly-(diacetone acrylamide-co-acrylamide) gel matrix, followed by solvent displacement method of introducing PEG200 and ionic liquids (ILs). It demonstrates dual-signal reporting and intelligent identification capabilities for strain, pressure and temperature, using mechanochromism, ionic mechanotransduction and ionic thermosensitivity respectively. Furthermore, PIskin possesses long-term stability (>20 d) in ambient air and maintains high stretchablility, bright structural color and outstanding conductivity even stay at extreme conditions (-20 °C–80 °C). Notably, the GML and ILs endow the PIskin with significant antibacterial ability for Gram-positive bacteria and fungus (>99.9% antibacterial rate). Based on these remarkable capabilities, the PIskin is integrated with Bluetooth transmission system to build an interactive wearable sensor for real-time remote digital/visual feedback of joint motion and tactile sensation (such as temperature and pressure), realizing wirelessly visual multi-sensing. This investigation provides a general and enlightening design strategy for constructing high-performance interactive skins based on photonic gels, and opens up more possibilities for meeting specific requirements in practical applications of wearable flexible devices, soft intelligent robots, human–machine interfaces and so on.