Highly stretchable, supersensitive, and self-adhesive ionohydrogels using waterborne polyurethane micelles as cross-linkers for wireless strain sensors.

Due to the rapid development of multi-functional flexible wearable sensors, the development prospects of ionohydrogels with excellent mechanical properties and high sensitivity are necessary. In this work, a novel waterborne polyurethane (WPU) micelle with reactive groups on the surface has been prepared as a crosslinker and then reacted with polyacrylamide (PAM) to obtain a polyacrylamide-polyurethane/ionic liquid (PAM-WPU/IL) ionohydrogel. With the aid of ion-dipole interaction and crosslinks in the composite, the ionohydrogel exhibited ultrastretchability (up to 2927%), good mechanical resilience, and excellent self-adhesion strength (46.01 kPa). Furthermore, the ionohydrogel was used as a strain sensor for monitoring human movement with high strain sensitivity (gauge factor = 35). It is believed that this study provides a new idea for designing a multifunctional ionohydrogel for use in wearable electronics.