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Acoustic Levitation Works On Small Animals
anthemaniac writes "Researchers for at least two decades have used acoustic levitation to suspend light materials without a container. Wenjun Xie, a materials physicist at Northwestern Polytechnical University in China, has previously used ultrasound fields to levitate globs of iridium and mercury, very heavy materials. Now the scientist has performed the feat with live animals. From the story: 'Xie and his colleagues employed an ultrasound emitter and reflector that generated a sound pressure field between them. The emitter produced roughly 20-millimeter-wavelength sounds, meaning it could in theory levitate objects half that wavelength or less.' Apparently the ants, spiders and ladybugs endured the trick just fine, but the fish didn't do so well due to lack of water."
One might also wonder about some of the biological effects of energy this high, especially with animals that contain more water. Heating is always a concern and something that many high powered ultrasound devices have not adequately addressed with developing biological systems.
As an aside, I seem to remember that former Admiral Bobby Inman served on the board of directors for (SAIC) and was involved in some acoustic work along these lines, but I think they were focusing on inanimate objects. I could be wrong about that, but it came out of a conversation I had years ago with members of the science directorate.
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These experiments were performed with 20 mm wavelangth sound. Thats 50 Hz to you and me. So how long until the guys with the subwoofer equipped cars convert them to hovercraft?
17 kHz is audible to humans and most animals. I wonder how loud the sound was in order to achieve levitation.
About this loud.
Indeed. We have this little chestnut to roast too:
"...has previously used ultrasound fields to levitate globs of iridium and mercury, very heavy materials."
A 1 gram 'glob' of mercury is equal in weight to 1 gram of feathers. Iridium and mercury may have a higher density, but they are not intrinsically heavy.
When even the author of an article is confused about basic physical properties you have to worry, IMHO.
I need a rest between naps some days