Ultra-stretchable wearable strain sensors based on skin-inspired adhesive, tough and conductive hydrogels

With increasing interest and demand for wearable sensor devices, fabricating a flexible hydrogel sensor combining high toughness and adhesiveness is necessary but remains challenging. In this work, inspired by the delamination structure of skin, an ultra-stretchable wearable hydrogel strain sensor with double layers is successfully prepared via in-situ polymerization of nucleobase-driven adhesive hydrogels on the surface of conductive tough hydrogels crosslinked by hydrophobic association. The hydrogel exhibits ultra-stretchability, high mechanical strength, and robust adhesion to various solid materials as well as skin. Furthermore, the hydrogel also exhibits high strain sensitivity and stability as a flexible and wearable strain sensor to detect large-range human motions and tiny physiological signals. Notably, the adhesive layer not only ensures a robust adhesion between the sensors and skin, but also protects skin from current harm when the hydrogels contact with skin directly, because of effectively blocking the current from the conductive tough layer. It is envisioned that the skin-inspired strategy would provide novel inspiration for the development of hydrogel strain sensors.