Gradient-segmented flag triboelectric nanogenerator for omnidirectional wind sensing and self-powered warning

Extreme wind events are increasing due to environmental degradation, often causing power outages and safety risks. To enable reliable sensing under such conditions, a gradient-segmented flag triboelectric nanogenerator is developed for omnidirectional wind sensing and self-powered warning. The polyethylene terephthalate-based flag with gradient thickness provides tunable stiffness and mass distribution, optimizing response range and sensitivity. A cantilever beam model elucidates the segment-dependent dynamics. The single-segment device achieves ∼500 nC charge output and 215 mW/m2 power density at 6.5 m/s, powering 434 LEDs, while the three-segment design enables accurate wind speed detection from 2 to 7 m/s. A hybrid system integrating both modes and a wind direction–adaptive structure ensures omnidirectional performance. This work demonstrates a robust, self-sustained solution for wind sensing and warning, capable of operating during power failures and supporting disaster risk mitigation.