Hydrophobic Association Hydrogel Enabled by Multiple Noncovalent Interactions for Wearable Bioelectronics in Amphibious Environments

Functionalized hydrogels integrating soft nature and electrical properties are of great significance for the development of human–machine interfaces, smart wearable devices, and biomimetics robotics. However, the hydrogel-based flexible sensors are inevitably utilized in aquatic environments, resulting in swelling-induced inferior mechanical performance, skin-component delamination, and monitoring malfunction. Herein, a multiple dynamic-bond-driven hydrophobic association hydrogel with reliable water resistance, mechanical robustness, and stable electrical property is proposed via a "two-step" method including micellar copolymerization and postsoaking strategy. Benefiting from the electrostatic interacted hydrophobic segments formed by myristyl methacrylate in the presence of cetyltrimethylammonium bromide micelles, the transparent hydrogel exhibits desirable antiswelling feature, excellent stretchability (∼1500% elongation), and toughness (∼2.4 MJ·m–3). The synergistic mechanisms of hydrophobic association and ultrasound dispersion endow the hydrogel with repeatable wet-adhesion behaviors. Moreover, the as-prepared hydrogel possesses significant conductivity and storage durability owing to the chitosan chain entanglements, electrostatic interactions, and strong hydrogen bonding established by sodium phytate. As a demonstration, a flexible sensor is fabricated to transmit various human movement signals and wirelessly monitor electrocardiography in both air and underwater based on its wide sensing range (∼500%) and linear sensitivity. This study offers an effective strategy for developing wearable electronic systems for amphibious scenarios.