Engineering 3D piezoelectric ZnO tetrapod interfaces for on-demand antibacterial skin-contact wearables

Prolonged skin contact with wearable sensors can promote perspiration-induced bacterial accumulation and biofilm formation, potentially compromising device performance and long-term health monitoring. Here, we introduce a flexible 3D piezoelectric ZnO tetrapod-poly(vinylidene fluoride) (ZnO-Ts/PVDF) composite that enables on-demand antibacterial activity without relying on antimicrobial-agent leaching. The unique 3D morphology of ZnO tetrapods enhances charge generation under mechanical deformation and ultrasonic activation, promoting localized electron transfer and reactive oxygen species (ROS) formation that contribute to bacterial membrane damage. The composite exhibited > 98% bactericidal efficiency under mechanical stimulation and > 90% under ultrasonic stimulation. Wearable time-course studies on human skin at 8, 16, and 24 h demonstrated a substantially lower recoverable culturable bacterial burden on ZnO-Ts/PVDF than on pristine PVDF under both dry (forearm) and humid (toe) conditions. The film also exhibited excellent durability, retaining > 95% antibacterial activity over 20 days. Collectively, these findings demonstrate a flexible and reusable piezoelectric antibacterial platform in which morphology-assisted membrane disruption and stimulation-induced oxidative processes contribute to antibacterial activity. This platform provides a promising strategy for self-cleaning, skin-contact wearable and biomedical interfaces.