Self-healing hydrogel with multiple adhesion as sensors for winter sports

Hydrogels are widely used as sensors in the field of wearable devices. However, the hydrogels were rarely designed to endure the harsh outdoor environment in winter, including extremely low temperature, ultraviolet (UV) radiation and variable humidity. In addition, physical damage is also a challenge for hydrogels. In this study, a self-healing hydrogel with adhesion was prepared as a sensor for winter sports using a one-pot method. Polyvinyl alcohol was used as the hydrogel matrix, providing the hydrogel preferable self-healing properties and adhesion to various surfaces such as porcine skin, metal, glass, and plastic. Lithium chloride was used for the chain entanglement of polyvinyl alcohol, forming a hydrogel with excellent ionic conductivity (24.29 S m^-1 at room temperature, 13.45 S m^-1 under -18 ℃) to detect human motion and temperature changes. Together with ethylene glycol, lithium chloride also provided successful water retention ability and frost resistance. The hydrogel remained stable after 30 d of storage at room temperature and -18 ℃. Sodium lignosulfonate was introduced to improve the mechanical properties and ultraviolet (UV) resistance of hydrogel, created nearly 100% UV shielding with a thickness of 0.5 mm. These advantages provide great potential to the hydrogel for application in flexible wearable devices for winter sports.