Antibacterial, Self-Adhesive, Recyclable, and Tough Conductive Composite Hydrogels for Ultrasensitive Strain Sensing

Owing to the characteristics of mimicking human skin's function and transmitting sensory signals, electronic skin (e-skin), as an emerging and exciting research field, has inspired tremendous efforts in the biomedical field. However, it is frustrating that most e-skins are prone to bacterial infections, resulting a serious threat to human health. Therefore, the construction of e-skin with an integrated perceptual signal and antibacterial properties is highly desirable. Herein, the dynamic supramolecular hydrogel was prepared through a freezing/thawing method by cross-linking the conductive graphene (G), biocompatible polyvinyl alcohol (PVA), self-adhesive polydopamine (PDA), and in situ formation antibacterial silver nanoparticles (AgNPs). Having fabricated the hierarchical network structure, the PVA–G–PDA–AgNPs composite hydrogel with a tensile strength of 1.174 MPa and an elongation of 331% paves way for flexible e-skins. Notably, the PVA–G–PDA–AgNPs hydrogel exhibits outstanding antibacterial activity to typical pathogenic microbes (e.g., Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus), which effectively prevents bacterial infections that harm human health. With self-adhesiveness to various surfaces and excellent conductivity, the PVA–G–PDA–AgNPs composite hydrogel was used as strain sensors to detect a variety of macroscale and microscale human motions successfully. Meanwhile, the excellent rehealing property allows the hydrogel to recycle as a new sensor to detect large-scale human activities or tiny movement. Based on these remarkable features, the antibacterial, self-adhesive, recyclable, and tough conductive composite hydrogels possess the great promising application in biomedical materials.