Stretchable Ionics – A Promising Candidate for Upcoming Wearable Devices

Abstract As many devices for human utility aim for fast and convenient communication with users, superb electronic devices are demonstrated to serve as hardware for human–machine interfaces in wearable forms. Wearable devices for daily healthcare and self‐diagnosis offer more human‐like properties unconstrained by deformation. In this sense, stretchable ionics based on flexible and stretchable hydrogels are on the rise as another means to develop wearable devices for bioapplications for two main reasons: i) ionic currents and choosing the same signal carriers for biological areas, and ii) the adoption of hydrogel ionic conductors, which are intrinsically stretchable materials with biocompatibility. Here, the current status of stretchable ionics and future applications are introduced, whose positive effects can be magnified by stretchable ionics.