Bio-inspired visual multi-sensing interactive ionic skin with asymmetrical adhesive, antibacterial and self-powered functions

Despite the rapid development of flexible wearable devices, the current ionic skins still remain a challenge to simultaneously realize visual dynamic display, multi-signal sensing, together with asymmetrical adhesive, antibacterial and self-powered functions for motion monitoring, thus severely limiting their practical applications in artificial intelligence and human–machine interaction. Herein, a multifunctional interactive ionic skin (MIIS) with these attractive functions is first presented by an asymmetrical double-layer structural color hydrogel (ADSCH) for visual and digital detecting human motions in real-time. The ADSCH is constructed by combining a highly stretchable, inverse opal structural polycationic hydrogel as the upper layer with a soft, adhesive polyanionic hydrogel as the lower layer using the sacrificial template and layer-by-layer polymerization methods respectively. The resultant ADSCH not only possesses electrical signal monitoring through the change of resistance, but also shows intuitive optical sensing by regulating the lattice spacing of photonic crystal under external strain and pressure stimuli at wide ranges (0–500%; 0–40 kPa). More importantly, the ADSCH is concurrently integrated with outstanding asymmetrical adhesion (adhesion strength: ∼30 kPa), antibacterial (log reduction: >4.44) and self-powered functions. Therefore, this study provides novel insights into for the design and fabrication of multifunctional interactive wearable devices.