Skin‐Covered Biohybrid Robotic Finger with Bilayered Permeable Subcutaneous Support for Internal Hydration Supplement

Integrating living tissues with robotic systems presents unique opportunities for developing next‐generation robots. This study addresses a critical challenge in skin‐covered biohybrid robots: maintaining a hydration supply to prevent rapid drying of living tissue in air‐exposed environments. A bilayered permeable subcutaneous support system, comprising a perforated skeletal layer and a permeable sponge‐like hydrogel layer made of polyvinyl alcohol (PVA), is proposed. The 3D‐printed skeletal layer, designed with dense perforations, provides structural strength for joint motion while allowing for fluid flow. The sponge‐like PVA hydrogel layer supports nutrient permeability and functions as a mechanical cushion beneath the dermal layer. The results demonstrate the sponge‐like PVA hydrogel's ability to retain moisture and allow the diffusion of nutrient molecules, effectively preventing dehydration of the cultured skin tissue. This approach offers a promising solution for enhancing the operational durability of skin‐covered robots, supporting their potential use in dynamic, real‐world applications.