Airborne Ultrasonic Emission Based on Asymmetric Vibration

This paper proposes a structure of an electrostatically driven thin transducer for high-intensity airborne ultrasound. The proposed transducer generates ultrasound by asymmetric vibration. The air between a diaphragm and a backplate is used as a nonlinear spring. The diaphragm is driven by converting electrostatic energy into acoustic energy of the air. In the experiment, the diaphragm velocity reached 0.27 m/s in the spatially averaged value and 4.5 m/s in the maximum value in the diaphragm. The vibration velocity of 0.27 m/s is equivalent to 112 Pa. However, we could not observe a continuous ultrasound since the velocity decelerated in a shorter duration than we expected.