Conductive Hydrogels and Their Applications in Flexible Electronic Devices

Hydrogels are 3D cross-linked polymer network which are formed by crosslinking polymer chains rich in hydrophilic groups in water. They have become an important structural and functional material for flexible electronic devices due to superb flexibility, ductility, interfacial adhesion, self-healing, biocompatibility and other characteristics, as well as high electrical conductivity obtained by adding ions to them. In recent years, hydrogel materials have gained widespread attention and their properties have been markedly improved, which has contributed to the advancement of flexible electronic devices. In this paper, the significant advances in molecular design and performance regulation of conductive hydrogels were reviewed, with focus on the enhancement of conductivity, mechanical properties, self-healing and anti-freezing property. In addition, the applications of conductive hydrogels in flexible sensors, flexible energy storage devices and flexible bioelectric electrodes were summarized. Finally, the opportunities and challenges of conductive hydrogels in flexible electronics were discussed.