Water-resistant conformal hydrogels toward underwater human-machine interfaces based on synergistic immersion method and supramolecular interactions strategy

Abstract

Flexible electronic skin based on hydrogel provides a non-invasive method for real-time acquisition of body movement signals and biosignals, which is essential for future smart health monitoring and healthcare. However, it is critical yet challenging to achieve motional and physiological signals monitoring in an aquatic environment because the interface electrodes may lose their conformability under wet environments. Here, inspired by the CB[8] enhanced hydrophobic polar–π interactions, hydrogel electrode based on the synergistic immersion method and supramolecular interactions is introduced, which exhibits excellent underwater conformability while maintaining tissue-mimetic mechanical properties. No need to add any organic solvents or hydrophobic monomers, the immersion behavior strengthens the non-covalent interactions in the network, and the conformal hydrogel sensor based on hydrophilic monomers has outstanding underwater adhesion capacity (adhesion strength of 139.62 kPa), excellent mechanical behavior (toughness of 5812.31 kJ m−3), and superior underwater stability (swelling ratio of 0.01) by rationally modulating the gel factors and immersion time. The ability to sensitively monitor movement signals and electrocardiogram (ECG) in multiple wet environments offers unique prospects for the development of next-generation wearable medical devices based on the facile preparation strategy.