Ionic conducting hydrogels as biomedical materials: classification, design strategies, and skin tissue engineering applications

Ionically conductive hydrogels (ICHs) are considered promising flexible electronic devices and various wearable sensors due to the integration of the conductive performance and soft nature of human tissue-like materials with mechanical and sensory traits. Recently, substantial progress has been made in the research of ICHs, including high conductivity, solution processability, strong adhesion, high stretchability, high self-healing ability, and good biocompatibility. These advanced researches also promote their excellent application prospects in medical monitoring, sports health, smart wear, and other fields. This article reviewed ICHs' current classification and design strategies in biomedical applications and the structure-activity relationship of the interface between biological systems and electronics. Furthermore, the typical cases of frontiers of skin interface applications of ICHs were elaborated in transdermal drug delivery, wound healing, disease diagnosis and treatment, and human-computer interaction. This article aims to inspire related research on ionically conductive hydrogels in the biomedical field and promote the innovation and application of flexible wearable electronic device technology.