Moving Objects With Sound Waves, It’s Possible
July 24, 2021Moving objects without physical contact, sounds like something out of a science fiction movie. But scientists have been using light to move microscopic objects for many years. However, there is an inherent limitation to this method. Only objects with certain properties can be manipulated this way.
But researchers from Tokyo Metropolitan University have developed a new technology that can accomplish this feat through the use of sound waves. Using sound instead of optical waves allows for a wider range of objects and materials to be used. As such, objects as big as millimeter-sized particles can be moved easily.
Though this technology is still in its infancy, researchers say it shows promise for lab settings and beyond. It isn’t easy to control vast arrays of ultrasound transducers and get them to lift objects with the right sound fields. This becomes more difficult to accomplish if the particles are near or on surfaces that reflect sound.
Credit: The Japan Society of Applied Physics (Citation Shota Kondo and Kan Okubo 2021 Jpn. J. Appl. Phys. 60 SDDD16)
That’s why researchers Shota Kondo and Associate Professor Kan Okubo from Tokyo Metropolitan University have come up with a new approach. They used a hemispherical array of ultrasound transducers to generate 3D acoustic fields. They were able to stably trap and lift a small polystyrene ball from a reflective surface.
This method involves: “Splitting the array into manageable blocks and using an inverse filter that finds the best phase and amplitude to drive them to make a single trap at some distance from the transducers themselves.”
Click here for the demonstration video.
And by adjusting how they drive the blocks over time, the researchers can change the position of their target field, then move the particle to the intended location. Besides using a polystyrene ball to prove the feasibility of their method, they also used simulations of the 3D acoustic fields created by the arrays, to verify their claim.
That said, there are still hurdles that need to be overcome such as keeping said particles trapped and stable for an extended period of time. But this technology shows promise toward transforming acoustic trapping into a practical way of moving objects.
