An ultrasonic fine droplet collector

It has been a big challenge to effectively collect coarse and fine droplets from the air by compact and light equipment. In this report, a novel strategy of collecting coarse and fine droplets from the air, which employs an ultrasonic field in the air gap between a flat radiation surface and parallel reflector, is demonstrated. Coarse and fine droplets (PM2.5-10 and PM2.5) can be effectively collected onto the reflector´s surface when the air gap thickness is proper. The radiation surface works in a flexural vibration mode at 56.9 kHz, and the collected droplets may form concentric rings and irregular shape on the reflector´s surface. Analyses show that both of the acoustic streaming and acoustic radiation force are responsible for the collection.