Hydrogel‐Based Multifunctional Soft Electronics with Distributed Sensing Units: A Review

Abstract

AbstractSoft electronics have attracted great interest owing to their potential applications in electronic skins, implanted devices, soft robotics, etc. Among the various soft materials, hydrogels are recognized as an ideal building block of soft electronics due to their tissue‐like physicochemical properties, abundant stimuli‐responses, and excellent mechanical compliances. Compared to elastomers, hydrogels containing large amounts of water exhibit better mechanical match to soft tissues and permeability to hydrophilic molecules. To date, most hydrogel‐based soft electronics (HSE) are facilely developed using a bulk conductive gel as the sensing unit, different from the elastomer‐based soft electronics with sophisticated integration of electronic elements. To advance their applications in engineering and biomedical fields, it is significant to devise hydrogel electronics with distributed sensing units. This Review summarizes the fabrication and applications of HSE, focusing on the multifunctional HSE with patterned conductive circuits and distributed sensing units. First, the fabrication of single‐functional soft electronics is briefly introduced with a bulk gel as the building block, including strain, temperature, chemical, and proximity sensors. Then, the approaches to integrating multiple sensing units into one hydrogel are summarized with examples of applications. Finally, perspectives are given on future directions and potential challenges in this field.