Core-shell droplet generation device using a flexural vibration by a bolt-clamped Langevin type ultrasonic transducer

Abstract:
A droplet with a core-shell structure formed from two immiscible liquids has been required widely in industrial fields. The efficient generation of uniform core-shell droplets has an important role. In previous studies, mono-disperse single droplets were generated with a high productively by using an ultrasonic torsional transducer and a micropore plate. In this research, mono-disperse core-shell droplets have been generated using a flexural bolt-clamped Langevin-type transducer and two micropore plates. The core-shell droplets were generated in the air when water and silicone oil were used as the core and shell phases. When the applied pressure of core phase, the applied pressure of shell phase and the vibration velocity in micropore were 200 kPa, 150 kPa and 8.2 mm/s, the average diameter and the coefficient of variation of droplets were 207.7 µm and 1.6 %. The 29,000 core-shell droplets were generated per second. This result shows that the proposed device is effective for the generation of mono-disperse core-shell droplets.