3D‐Printable, Biodegradable, and Conductive/Piezoionic Hydrogel ‘ E‐Skin ’ With Robust Antibacterial Properties for Wound Healing and Wireless Human‐Machine Interface Sensing

Soft multifunctional materials that seamlessly integrate bioelectronics with therapeutic functionality are critical for next‐generation human‐machine interface (HMI) systems. Herein, we report a three‐dimensional (3D)‐printable, biodegradable, and piezoionic/conductive hydrogel ‘ E‐skin ’ based on a double‐network gelatin methacrylate/alginate reinforced with TEMPO‐oxidized cellulose nanocrystals (TOCNCs) and Ti 3 C 2 T x (MXene) nanosheets (=GACM hydrogel). The as‐fabricated nanocomposite hydrogel exhibits higher compressive strength (∼21 kPa), stable adhesion on diverse dry and wet substrates, and shear‐thinning property that allows high‐resolution direct ink writing (DIW) printing of complex architectures. Owing to the MXene‐enabled conductive/piezoionic features, the GACM hydrogel functions as a self‐powered sensor with a gauge factor of ∼1.77 at 80% compressive strain. It generates physiologically relevant voltage outputs (∼36.35 mV) under mechanical deformation. Beyond sensing, the platform acts as a smart wound dressing, supporting robust in vivo wound healing, enabling pH‐responsive drug release, and exhibiting strong bactericidal activity. Importantly, the GACM hydrogel is successfully integrated into a wireless HMI, enabling real‐time robotic control from human motion. This work establishes a versatile and sustainable hydrogel biointerface that integrates 3D printability, self‐powered sensing, infection management, and accelerated wound healing, offering a compelling materials framework for future bioelectronic skins and regenerative healthcare technologies.