Dual-Network Conductive Hydrogels with Self-Healing, Ultrasensitive, and Antibacterial Activity toward Multifunctional Flexible Strain Sensor

Flexible strain sensors based on hydrogels have shown promising application prospects in artificial tissue and body deformation monitoring. However, hydrogel-based sensors with ideal structural performance, self-healing ability, strain detection, and tissue adhesion remain challenging. Herein, a dual-network hydrogel (PG-B-T) flexible sensor based on poly(vinyl alcohol) (PVA) and gelatin was developed, which were multidynamically cross-linked via the one-pot approach. The noncovalent bonds of gelatin cross-linked by tannic acid (TA) could form the first network and impart structural stability with antibacterial performance, while the second network constructed with reversible borate ester bonds by PVA and borax showed the capability of self-healing and electric conductivity. As such, the prepared PG-B-T hydrogel demonstrated exceptional ductility (strain >1000%) and high sensitivity (GF = 2.51). In air or an underwater environment, the PG-B-T hydrogel can perform a wide working range, such as self-healing capability, electrical properties, and sensing properties. Meanwhile, the hydrogen bonds of gelatin enabled strong adhesion to some classic substrates, not only allowing the hydrogel to monitor body movements and detect vocal vibration signals but also achieving underwater information transmission of Morse code via finger movement. Consequently, this work provided a significant strategy for developing multifunctional hydrogels as strain-sensitive sensors that could conveniently and effectively detect motion variation.