Bio‐Inspired Ionic Skin for Theranostics

Abstract The first‐generation ionic skins demonstrate great advantages in the tunable mechanical properties, high transparency, ionic conductivities, and multiple sensory capacities. However, little attention is paid to the interfacial interactions among the ambient environment, natural organisms, and the artificial skins. In particularly, current ionic skins based on traditional synthetic hydrogels suffer from dehydration in vitro and lack of substance communication channels with biological tissues. Herein, this work develops a bio‐inspired hydrogel to address these key challenges. The hydrogel is designed with natural moisturizing factors to lock water, biomineral ions to transmit signals, and biomimetic gradient channels to transport substances from non‐living to living interfaces. It is stable in ambient condition, adhesive and hydrated on mammal skins, and capable of non‐invasive point‐to‐point theranostics. This theranostic ionic skin realizes sensitive detection, enhanced treatment efficacy, and reduced side effects toward major diseases in vitro. It will shed light on the hydrogel bioelectronics with excellent biocompatibility, bio‐protection, and bio‐integration for human–machine interfaces and intelligent theranostics.