Antibacterial conductive hydrogels with freeze-directed microstructures reinforced by polyaniline-encapsulated bacterial cellulose for flexible sensors

Hydrogels with superior mechanical strength, conductivity, and recyclability are critical for advancing flexible wearable sensors. However, achieving a balance among these properties while ensuring antibacterial functionality and environmental sustainability remains a significant challenge. Here, we present a polyvinyl alcohol-based anisotropic hydrogel (PTPB) reinforced with polyaniline-encapsulated bacterial cellulose fibers. The hydrogel achieves a fracture stress exceeding 2 MPa and a maximum toughness of 3.75 MJ/m³ while maintaining stable sensing accuracy across strains up to 200 %. It exhibits robust sensing capabilities for human motion and electrocardiogram (ECG) signals, with performance comparable to commercial Ag/AgCl electrodes. Additionally, the hydrogel demonstrates exceptional antibacterial activity against E. coli and S. aureus, attributed to the inclusion of tannic acid. The recyclability of PTPB hydrogel is enabled by its thermal remolding capability, allowing dissolution at 90 °C followed by directional freezing to reform the material. Recycled hydrogels retain over 90 % of their original gauge factor and conductivity, with minimal loss in mechanical strength. These properties establish PTPB hydrogel as an environmentally sustainable and high-performance material for next-generation wearable sensors and biomedical applications.