Skin-inspired ultra-tough, self-healing anisotropic wood-based electronic skin for multidimensional sensing

Skin is a flexible and stretchable sensor composed of anisotropic dermis (DM) and repairable epidermis (EM). It repairs itself when damaged and has a multi-dimensional sensing system that can assist the body in performing some complex multi-dimensional movements. Inspired by skin, we utilized natural wood as the skeleton and for the first time designed a low-cost, double-layer structure wood-based electronic skin (wood-eskin). Simple chemical treatments were employed to directionally regulate the ray structure of natural wood and to enhance its porosity. Subsequently, physical freeze-thawing was employed to facilitate the formation of an entangled network structure between the PVA solution and the wood nanofibers. Wood-eskin with multi-dimensional sensing was obtained by further introducing ions by immersing in salt solution. In comparison to the majority of contemporary bionic e-skins, wood-eskin exhibits superior mechanical properties. Additionally, it is capable of performing complex deformations, such as bending and knotting. After fracture, wood-eskin can also repair itself and recover ~94% of its mechanical properties. The oriented arrangement of cellulose nanofiber channels gives wood-eskin a multidimensional sensing capability that can be used to monitor more complex body movements. The low-cost, biodegradable wood-eskin exhibits similar functionality to human skin, and its potential for biomedical and bionic robotics applications is considerable.