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This incredible sound wave system can make particles levitate

Published Dec 18th, 2018 2:18PM EST
acoustic tweezers

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We’ve already seen sound waves do some pretty amazing things. For example, they can turn a regular, boring stream of water into a mesmerizing work of moving art, and even cause small particles to float in mid-air. Now, researchers have developed a powerful sound wave system that not only causes objects to seemingly defy gravity, but also allows each particle to be manipulated independently for the first time.

The system, which the scientists have called “Holographic Acoustic Tweezers,” is detailed in a new paper published in the Proceedings of the National Academy of Sciences, but a video showing the technique in action is probably the best way to understand its capabilities.

The system is uses a total of over 500 tiny speakers arranged in two panels of 256 speakers each. The sound waves produced by the speakers act like an invisible grid that can trap low-weight particles in space and allow them to be moved independent of one another.

The strength of each speaker’s output, and their ability to change on the fly to allow particles to move to new areas of 3D space, is the key to allowing each individual object to move freely. You might think that a system using over 500 speakers would cause quite a bit of residual noise but the sound waves actually fall outside of the range of human hearing. It’s completely quiet to the operator.

In the video you can see tiny foam spheres moving in a variety of interesting patterns that are controlled by the scientists. This creates what is effectively a physical “hologram” effect that feels very futuristic. In fact, the team suggests that a system could be used for eye-catching new display technologies, but its potential applications don’t stop there.

To demonstrate how robust the system is the team “assembles” some simple objects and even threads a floating hole with a string suspended by two of the levitating foam spheres. Obviously it would take some time for a system like this to be adapted for a real-world application, but there’s clearly a lot of potential here.