Levitation. Some magicians have very good tricks, and then we find many people playing with magnets or sub-zero temperatures, but there is another option: acoustic levitation. Using a series of precisely calibrated sound waves, laboratories can create small vacuums that cancel gravity. The effect has limits regarding object size (three millimeters maximum) and sound power, but it still offers very interesting applications.
Maglev trains, sub-zero temperature experiments on YouTube, new forms of advertising. Levitation is not science fiction, of that we are sure, but it usually comes hand in hand with magnets and unusual materials. However, there is another variant involving sound. Acoustic levitation is not new here at NeoTeo. In 2014 we explored the control techniques used by Japanese scientists, but it was in 2012 that Argonne National Laboratory showed us its fabulous device. That's where we travel once more thanks to Wired, which interviewed one of the leading physicists at that institution, Chris J. Benmore:
How Acoustic Levitation Works
In its simplest definition, acoustic levitation uses sound waves to generate a force that counteracts gravity. Its original development came from NASA in the '60s, but it has gained much traction in the last decade, and the world's most important institutions already have access to this technology.
Argonne's device is based on two transducers that vibrate their respective horns about 22,000 times per second. The interaction between the two waves creates what is known as a standing wave. In some points, the waves reinforce each other, while in others they cancel completely (nodes and antinodes). It is in those vacuums or antinodes where a person can place objects and make them float in the air.
https://old.neoteo.com/observa-la-fabulosa-interaccion-cobre-los-imanes-neodimio/One of the most impressive aspects of the device is that when active it generates sound with an intensity equivalent to that of a rock concert, but we can't hear it. Those with a younger ear might be able to register a slight pulse, but nothing more than that (22 kHz is at the limit of what a human ear can hear). The antinodes have a diameter of six millimeters, and the maximum size of the object to levitate must not exceed half that value. Each object seems to snap into the correct position, almost like a 'snap' effect.
Another fundamental advantage of acoustic levitation is that it allows experts to work with liquids. This enables the study of individual droplets in a microgravity space, and the reaction of different drugs with the help of X-rays, checking the interaction of their molecules to then optimize the formula and obtain even more effective variants. Now, levitating larger objects presents a considerable challenge, but the use of networked transducers and more precise control of generated waves can expand the possibilities of this technology.
