Skin-like Hydrogel Devices for Wearable Sensing, Soft Robotics and Beyond

Summary Skin-like electronics are developing rapidly to satisfy applications including wearable sensing and soft robotics. Hydrogels as soft biomaterials have been studied intensively for skin-like electronic utilities due to their superior softness, wetness, responsiveness, biocompatibility and unique ionic sensing nature. Those features could potentially blur the gap between soft bodies and hard machines. However, the development of skin-like hydrogel devices is still in the infancy and facing challenges including limited functionality, low stability, poor surface adhesion and large power consumption. This review aims to summarize current development to address these challenges. We first conduct an overview of hydrogels and existing strategies to increase their toughness and conductivity. Next, we describe current approaches to leverage hydrogel devices with enhanced merits including their anti-dehydration, anti-freezing, and adhesion. Thereafter, we highlight state-of-art skin-like hydrogel devices for applications including wearable electronics, soft robotics and energy harvestings. Finally, we conclude and propose the future perspectives.