High performance Vector Ultrasound Anemometer based on Capacitive Micromachined Ultrasonic Transducers

Wind speed sensors provide fundamental measurements for applications ranging from environmental monitoring to autonomous systems. A Planar Vector Anemometer (PVA) can measure the speed and direction of wind on a plane. Standard PVAs are based on a mechanical setup composed of a directional air-foil and a tangential turbine. Their miniaturization is difficult, and reliability is penalized by the presence of mechanical moving parts, subject to friction and wear. Ultrasound PVAs address these limitations by measuring the time of flight of an ultrasound wave from two opposite sensors placed on two orthogonal axes. In these devices, the large size of typical sensors, i.e. 1 cm, 40 kHz piezoelectric ultrasonic transducers (PT), prevents further miniaturization due to the perturbation of the air flow by the sensors themselves (shading effect). In this study, we investigate the possibility to miniaturize PVAs by using a novel polymer-based capacitive micromachined ultrasonic transducer (CMUT) technology to reduce the sensors size and the total encumbrance of the PVA.