Hydrogel electronic materials and microfabrication processes for soft electronic applications

Hydrogel electronic materials (HEMs) have emerged as strong candidates for various applications in soft electronics based on their unique softness and exceptional ability to retain water. Central to the advancement of these materials are conjugated polymers, such as conducting and semiconducting polymers, which have been the focus of extensive materials science and engineering. Despite this progress, the practical application of HEMs necessitates the development of microfabrication techniques that allow for effective fabrication methodologies and precise patterning at a micro-scale. By reducing HEMs to micro-sized devices, various innovative technologies such as implantable electronics and imperceptible soft robots can be realized. In this review, we present the latest advancements in the design methods and microfabrication strategies for HEMs. Then, we also discuss the physical properties of fabricated HEMs and the methodologies to precisely measure them. Finally, we will introduce potential applications of soft electronics and conclude with the future direction of research in this exciting field.