Recent Advances in Hydrogel‐Based Self‐Powered Artificial Skins for Human–Machine Interfaces

With the rapid development of artificial intelligence, human‐machine interfaces (HMI) are continuing to affect human lifestyles. Artificial skin is a new type of HMI sensor that enables a seamless connection between human and electronic devices. Currently, artificial skin is mostly prepared from rigid materials, which lack flexibility and scalability, thus impeding the development of HMI. Hydrogel, consisting of 3D polymer network and water is similar to human tissues and is therefore an excellent candidate for artificial skin in HMI. The conventional HMI of hydrogel‐based artificial skin includes touch pad and machine control based on capacitive or resistive sensors. However, the energy supply of HMI depends on battery which requires frequent recharging and replacement. Therefore, hydrogel‐based self‐powered artificial skin is expected to become primary interaction medium for the forthcoming generation of HMI. This article reviews the development of hydrogel‐based self‐powered artificial skin for HMI. Various power supply mechanisms of hydrogel‐based artificial skin are discussed. The materials for self‐powered artificial skin are introduced, including ionic hydrogel, ionic‐liquid hydrogel, metal‐based hydrogel, carbon‐based and MXene‐based hydrogel, and conductive polymer‐based hydrogel. The application of the hydrogel‐based self‐powered artificial skin in HMI is also reviewed. Finally, the challenges and development trends in HMI are outlined.