Temperature-triggered adhesiveness-controllable ionic-conductive hydrogels for wearable electronic applications

Ionic-conductive hydrogels with controllable adhesiveness are essential for bioelectrical signal monitoring. However, highly adhesive hydrogels may cause discomfort to human skin, such as redness, swelling and pain when peeled off, which hinders their applications. Here, we designed a temperature-triggered adhesiveness-controllable ionic-conductive P(Acrylamide-co-1-vinyl-3 butylimidazolium bromide)/gelatin (short for PILG) hydrogel based on body temperature. Due to the temperature sensitivity of gelatin(the gelatin triple helix unfurls and exposes a large number of side groups when reaching the phase transition temperature), the developed hydrogel shows a rapid increase in adhesiveness when exposed to body temperature and a rapid decrease in a short time (10 s) after cooling, enabling pain-free and residue-free removal. At the same time, PILG hydrogel has excellent sensitivity ( GF =4.16) and can detect various bioelectrical signals and accurately identify movements. The conductive hydrogel with temperature-triggered adhesive changes shows great potential in this work for biomedical applications.