Synergistic Ion Interface Driven Moisture‐Enabled Active Hydrogel Generator for Flexible Bio‐Machine Interactive Electronics

ABSTRACT Hydrogel‐based moisture‐driven electric generators (MEGs) hold broad prospects in wearable fields by continuously harvesting ubiquitous ambient moisture while providing long‐term stable electricity. However, their potential application is limited by relatively low electrical output, limited flexibility, and a complex design process. Herein, we develop an ionic hydrogel composite with a synergistic ion effect as a flexible, reusable, high‐performance, and environmentally friendly material. By introducing a multivalent cation combination, a configuration of Fe 3 + (Stern layer of the electric double layer) and K + (diffuse layer of the electric double layer) is formed, thereby optimizing the gel network structure and ionic conduction characteristics and further enhancing electrical output performance. The ion concentration gradient‐driven long‐term hydrogel power generator, 1 cm 2 in size, can spontaneously produce an open‐circuit voltage of ∼1.35 V and a power output of ∼175 µW cm −2 . Furthermore, this moisture‐driven device is used for power generation from plant transpiration to drive small‐scale, biological, and flexible electronic devices. Through engineering programming strategies involving series and parallel circuits, human‐machine interaction is achieved, demonstrating its application in flexible wearable electronics. This work demonstrates significant potential for application in the design and engineering strategies of next‐generation flexible energy devices.