Inducing drop to bubble transformation via resonance in ultrasound
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Drops of liquid levitating on sound waves can be transformed into bubbles.
Making bubbles is important for manufacturing foams for a range of chemical products, but it is hard to prevent external forces from bursting the bubbles.
A team that included researchers from Northwestern Polytechnical University in China used sound waves to levitate a drop of liquid. They adjusted the sound field to first flatten the drop into a disk and then buckle it into a bowl shape. This created a cavity inside the drop.
The researchers rapidly inflated the drop into a bubble by gradually turning up the sound intensity until a critical point was reached. They could control the size of the bubble by adjusting the frequency of the sound wave.
Such precise control over bubble formation could allow chemists to tailor-make foams for cosmetics, food and pharmaceuticals.
- Nature Communications 9, 3546 (2018). doi: 10.1038/s41467-018-05949-0
|Northwestern Polytechnical University (NPU), China
|Monash University, Australia
|University of Hull, United Kingdom (UK)