Underwater sensors based on dual dynamically crosslinked hydrogels with excellent anti-swelling and adhesive properties

Hydrogel-derived flexible sensors have fascinating applications in the fields of wearable electronics and electronic skin. Nevertheless, the fabrication of underwater sensors is still restricted due to the underwater instability and the poor adhesion in an aquatic environment. In this work, a dynamic physical/chemical dual crosslinked poly (acrylic acid-co-lauryl methacrylate) and polyvinyl alcohol interpenetrating network hydrogel was successfully prepared to overcome the above issues. The as-prepared hydrogels exhibited prior stretchability (2310% strain), good self-healing performance (83% healing efficiency within 36 h), remarkable underwater instability (23% of equilibrium swelling ratio), and long-term underwater adhesion (65.4 kPa of adhesive strength in water for 24 h). The as-prepared hydrogel strain sensor features excellent sensing performance (GF = 4.83) and a wide sensing range of 1%–1000%. Due to its excellent flexibility, strong adhesion, and high strain sensitivity, the prepared hydrogel can be conveniently used for the real-time monitoring of various human movements, including pronounced joint movements and subtle muscle vibrations. Furthermore, the hydrogel-based sensor with good and stable mechanical, electrical, and adhesive properties in an aquatic environment can accomplish effective signal transmission underwater via the combination of body movement and the Morse code.