Flexible piezo-capacitive pressure sensor for measurement of wind speed and direction

Demand for autonomous flying vehicles intended for transportation of people and goods is expected to accelerate in the next few years as urban air mobility maturity reaches level-4, a rating implying that hundreds of flights will simultaneously take off from urban aerodromes around the country. Wind sensors available on the vehicles and located in the air space will become a key necessity for ensuring safe navigation. Conventional anemometers suffer from various drawbacks due to their non-aerodynamic construction, high power consumption, complex signal processing, and cost. An airfoil-shaped low drag anemometer is presented for wind speed and direction measurement on tethered systems such as kites, balloons, and drones. The airfoil anemometer is equipped with a flexible, dual-layer capacitive pressure sensor with a polyvinylidene fluoride (PVDF) diaphragm for wind speed and a commercial digital magnetometer for wind direction measurement. The fabrication process for the diaphragm-type capacitive sensor is presented, along with characterization of the sensor in a pressure chamber. The completed sensor is then integrated into a NACA-2412 profile airfoil, along with a commercial magnetometer, for demonstration in a laboratory-scale wind tunnel.