Curved flap array-based triboelectric self-powered sensor for omnidirectional monitoring of wind speed and direction

The real-time measurement of wind speed and direction in distributed locations is an important aspect of environmental monitoring. Wind sensors without an external power supply are desirable for ideal sensor systems. In this study, we demonstrate an omnidirectional wind-driven triboelectric nanogenerator that can be used as a self-powered wind sensor. The harvester consists of a flexible array of 12 flaps and a flat substrate. Aluminum and polytetrafluoroethylene are used as pairs of triboelectric materials on each surface. All flaps are plastically deformed to have a specific curvature in a single process, resulting in an upward curved triangle shape. When the flap array is oscillated by wind, energy is harvested through triboelectric energy conversion. The harvester can produce a constant output irrespective of the wind direction because the flaps are evenly located in the circumferential direction. Experiments confirm that the output voltage monotonically increases as the wind speed increases from 1.5 to 10 m/s, and it correlated with the angle between the wind and the flap. The maximum root-mean-square power density at a wind speed of 10 m/s is 0.76 mW/m2, which is sufficient to operate a wireless environmental sensor system for monitoring temperature and atmospheric pressure. It is also demonstrated that the harvester can be used for self-powered wind monitoring, as the magnitude of the voltages generated by the 12 electrode pairs is dependent on the speed and direction of the wind.