Evaluation of generated micro droplets using micropore plates oscillated by ultrasonic torsional transducers

This paper reports on generating micro and uniform droplets in various viscosity liquids by using a micropore plate oscillated by an ultrasonic torsional transducer. When the micropore plate was not oscillated, generated droplet diameter was not stable. On the other hand, when the micropore plate was oscillated, generated droplets became small and uniform by ruffling the liquid column surface. Droplets were generated experimentally in the air by using pure water and silicone oil of various viscosities and then evaluated. We have designed the ultrasonic torsional transducer and a droplet generation device to apply a high pressure for the use of higher viscosity liquids. We have succeeded in generating droplets by using pure water when the ultrasonic torsional transducer and the micropore plate that had an 18-μm-diameter micropore were used. The average diameter of droplets was 30.0 μm and the standard deviation was 0.98. We have also succeeded in generating 50-cSt silicone oil droplets by using the droplet generation device and the micropore plate that had the 50-μm-diameter micropore. The average diameter of droplets was 98.0 μm and the standard deviation was 0.76.