Conductive ionogel with underwater adhesion and stability as multimodal sensor for contactless signal propagation and wearable devices

Gathering information and giving feedback on it happen all the time for the human and animals. Soft materials such as hydrogels are often chosen as sensors due to their portability and wearability. However, these materials previously reported have various defects, such as poor underwater adhesion, underwater swelling, unstable underwater conductivity. Herein, a hydrophobic ionogel is prepared by ion-dipole and ion-ion interactions between fluorine-rich poly (ionic liquid) and ionic liquid, and covalent cross-linking. The conductive ionogel shows adjustable mechanical property (fracture strength: 0.24–0.52 MPa, break strain: 210% to 360%), underwater adhesion (693 KPa to plastic), optical transparency (81%, 2 mm), temperature tolerance and suitable conductivity (10−5-10−4 S/cm). Thus, the ionogel is used as s multimodal sensor no matter in the air or in aquatic environment. Based on the mechanism of electron transport path change, the ionogel sensor can recognize different objects entering water, and even different objects touching ice, such as hands, tweezers and aluminum foil, and send messages out of the water by Morse code. Even more, the standing posture and touching between two persons can be recorded by ionogel sensor. And the ionogels can be served as temperature sensor, containing wide operating temperature window (0–80 °C) and high detecting accuracy (0.2 °C). Therefore, the ionogel has vital important applications in non-contact signal propagation and wearable devices.