Members of “Makerspace” tried to make an experiment with standing sound waves, which theoretically could generate different layers of air pressure. In order to create the standing wave was used ultrasonic transducer, which is normally used for vibratory cleaning baths to make faster for plaque cleaning with solvents.
Experiment with standing sound waves is cool, because ultrasonic transducer with 40 kHz frequency sound waves and echo generate different layers of air pressure – each 8 mm (0.32 in). It’a like invisible shelves where every in between embedded object creates a lifting force or so called acoustic levitation. Look at this scheme:
It’s great that plenty of these layers can be formed. In video below you can see sea foam bubbles placed one by one. Take a look, it seems like a magic trick!
At that time, our workshop record was 11 bubbles, but 12 bubbles is too much, they are falling down. This device was later adjusted, placed into a beautiful casing and demonstrated through scientific events, the University Open Days. Acoustic levitation machine is fun for both young and older audiences!