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Acoustic Levitation Works On Small Animals 182

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."
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Acoustic Levitation Works On Small Animals

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  • by BWJones ( 18351 ) * on Wednesday November 29, 2006 @02:38PM (#17038238) Homepage Journal
    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.

    • by Red Flayer ( 890720 ) on Wednesday November 29, 2006 @02:52PM (#17038490) Journal
      Well, ultrasound is used to create the field... but the emitter that produces the waves for levitation has waves of much, much longer wavelength (and therefore much lower frequency). I think instead of at the molecular level, the concern would be at the macro level... that is, can animal tissue deal with rapid mechanical manipulation from the soundwaves?

      And is it possible for animals to have cavities or structures with a resonant frequency equal to that of the emitted waves? That's where the real danger lies, I think.
      • Re: (Score:3, Insightful)

        by Yvanhoe ( 564877 )
        Indeed. the fact that is reassuring is that there is no invisible harm like with microwaves. Here you will know you use to much energy when bones break...
      • Re: (Score:3, Funny)

        I'm glad someone else's mind went to resonant frequency on this one.

        "My new hoverboard was a lot of fun, until my duodenum imploded."
    • by inKubus ( 199753 )
      One word: hoverboard [wikipedia.org].
    • Re: (Score:3, Informative)

      You're concerned about organisms that contain MORE water? The specific heat capacity of water is greater than that of most materials, seems to me that more water would be a good thing.
    • Re: (Score:2, Funny)

      by sweetpapa ( 1033580 )
      Interestingly, after levitating for several moments, all subjects were found to be deaf to ultrasound.
  • by Red Flayer ( 890720 ) on Wednesday November 29, 2006 @02:40PM (#17038272) Journal
    Apparently the ants, spiders and ladybugs endured the trick just fine, but the fish didn't do so well due to lack of water."
    Well, if you put the fish in water, for some reason the restriction on the size of the fish being 1/2 the wavelength disappears.

    It's even easier to get fish to levitate in water if you never feed them.
  • I for one welcome our levitating ant overlords.
  • This concept is straight out of the worst episode [tv.com] of Farscape, and that's saying something.
  • by LiquidCoooled ( 634315 ) on Wednesday November 29, 2006 @02:47PM (#17038398) Homepage Journal
    I was once lay on the bed and my cat decided to curl up in the small of my back.
    When I let out a ripper of a fart I swear he hovered right there for about 15 seconds.

    (Incidentally, after that event he never lay on my back again)
  • "but the fish didn't do so well due to lack of water." To devise a fairer system of test, a team of our researchers spent eighteen months in Antarctica living like penguins, and subsequently dying like penguins - only quicker - proving that the penguin is a clever little sod in his own environment. /python
  • ...the fish didn't do so well due to lack of water

    I bet it was from the levitaiton. That's why they used fish. Needed another excuse ;-)

  • 50 Hz? (Score:3, Interesting)

    by fragMasterFlash ( 989911 ) on Wednesday November 29, 2006 @02:54PM (#17038534)
    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?
    • Re:50 Hz? (Score:5, Informative)

      by cnettel ( 836611 ) on Wednesday November 29, 2006 @02:58PM (#17038604)
      Ehum, only if sound travelled 1 meter per second in air. Hint: it doesn't. It's more like 340, hence the frequency is 50 * 340 = 17,000 Hz.
      • by hurfy ( 735314 )
        Wouldn't that much sound energy at that frequency be deafening or at least damaging? Do any of those critters hear?

        Anyways, off to catch critters to put between my speakers ;)
    • I get 17 khertz. How did you figure that?
  • by Rob T Firefly ( 844560 ) on Wednesday November 29, 2006 @02:56PM (#17038574) Homepage Journal
    Apparently the ants, spiders and ladybugs endured the trick just fine
    Actually, they're fairly pissed. They only seem "just fine" because they lack the proper fingers to angrily flip off the scientists.
  • Diminutive! (Score:4, Funny)

    by Short Circuit ( 52384 ) * <mikemol@gmail.com> on Wednesday November 29, 2006 @02:59PM (#17038614) Homepage Journal
    I'll have you know that none of those animals were small. The System Reference Document [systemrefe...uments.org] doesn't list them, but I'm confident they'd be identified as "diminutive," or smaller still.
    • I was just thinking, now I finally know how to get the one feat my drow wizard is still lacking. I just need to find the right frequency...
  • "but the fish didn't do so well due to lack of water"

    Is that even funny??
  • by ciaohound ( 118419 ) on Wednesday November 29, 2006 @03:06PM (#17038732)
    Now it's levitating spiders? I am so screwed.
  • And here I thought heavy metal just made you feel like you being bounced off the ground.
  • Nothing new (Score:3, Funny)

    by MECC ( 8478 ) * on Wednesday November 29, 2006 @03:18PM (#17038930)
    AC/DC has been doing it for awhile.

  • ...that sheep do not fly as much as they do plummet.
  • I once snuck up on and yelled "Boo" at a rather high strung cat. He levitated about three feet in the air for a moment too.

    That's acoustic levitation if I ever saw it.
  • by HangingChad ( 677530 ) on Wednesday November 29, 2006 @03:41PM (#17039324) Homepage

    I'm just walking along, minding my own ant business, and all of sudden some jackass decides to levitate me. Oh, that's right, it's so funny to pick on the ants. Everyone picks on the ants. We're just trying to make a living and feed the queen...she gets to drink nectar. Think the rest of us get any nectar? Not us worker ants. You try running around blind trying to follow a scent trail during allergy season. We get stepped on, eaten by other bugs and birds...don't get me started. And then there's the nursery, those ingrates never get enough. Like it's not bad enough putting up with their crap along comes to the dominant species and thinks it's just SO funny to levitate us. Suppose I should be glad they didn't roast us under a magnifying glass like the neighbor kid. Little delinquent. I'll be he grows up to be a career criminal. It's all so meaningless.

  • Excellent that this should be on Slashdot the same day I get James Blish's Cities in Flight book series. I, for one, can't wait till Pittsburgh relocates to Mars and starts a mining operation.
  • by kick_in_the_eye ( 539123 ) on Wednesday November 29, 2006 @03:47PM (#17039428) Homepage
    when pigs fly
  • I can levitate birds. Nobody cares.
  • No video clips of the insects and fish? :(
  • When my father used to yell, we'd come off the sofa a couple of feet.

  • This story is useless without video of a kitten slowly rotating in midair.
  • 20mm wavelength seems to be 17KHz (at sealevel in air), which isn't very "ultra" sound. To levitate the 3 meters radius of adult humans (with extended arms/legs), we'd need 6m wavelength. That's about 0.04Hz, which is infrasound. How much energy would have to input to an infrasound generator to levitate a 100Kg person?
    • 20mm wavelength seems to be 17KHz (at sealevel in air), which isn't very "ultra" sound. To levitate the 3 meters radius of adult humans (with extended arms/legs), we'd need 6m wavelength.

      Which is about 57Hz.

      How much power...well lots. Area of human (one side) about 1sq. m. mass, (order of magnitude) 100Kg, say 1KN force required = 1Megapascal. That's 10bar pressure, implying an acoustic pressure of 10dB above atmospheric..or 203dB into 4pi space.

      Imagine you had a 'regular' hifi speaker, radiating into half space..and that it behaved in a perfectly linear manner to power input (no chance!) at the typical 1% efficiency of electrical-to-acoustic conversion, you' need to hit it with, oh,

      • Thanks for fixing my math to find the required frequency. I'm looking for the energy delivered to the levitating person, not the required electric energy to produce it, because an electrical speaker isn't necessarily the power source.

        How much power does, say, Pavarotti's loudest singing in the 57Hz range (50-60Hz) deliver at, say, 10m? Maybe we're talking kilopavarottis.
        • ...talking kilopavarottis.

          You mean KPa? Clearly the SI unit of pressure. The Pavarotti - (Pa). Everyone knows Pascal wasn't much of a singer.

  • I want to know when they're going to figure out how to use these sonic waves to drive screws.
  • Very cool video of them levitating all kinds of light things.

    The first thing I wondered while watching is: why can't you flip that device upsidedown, increase the power, and make the ultimate hovercraft? This technology seems like it has military applications written all over it. And one poster has already mentioned Bobby Inman worked on this technology back in the 80's. Bobby Inman [wikipedia.org] is definitely military (intelligence though, not R&D or skunkworks).

    I'm not suggesting some super secret conspir
    • Seems to me that there have been a few cases of the navy using "experimental high powered sonar that caused extreme distress to marine life. Several incidents caused dolphins, etc. to beach themselves; they were found to be bleeding from the ears. Of course that portion of the sea was closed to the public during the trials for security reasons.

      I'm not saying that the navy was doing levitation experiments, but wouldn't you expect it to look something like that if they were?

      Just occurred to me that, even if
      • Yes, I would expect to see some "damage" -- and perhaps that's why we aren't seeing anything in this space. Maybe it's too damaging (and loud) to be effective? I mean, if your enemy can detect seismic activity when you come to storm the beaches, there is not much point.

        I think you are right about the defenses part of it though. In fact, recently, somewhere near Africa (I think) there was a cruise ship that was attacked by pirates (real pirates). They used some kind of acoustic defense to repel the
        • "In fact, recently, somewhere near Africa (I think) there was a cruise ship that was attacked by pirates (real pirates). They used some kind of acoustic defense to repel the attack."

          The system you are referring to was an open-air sonic defense, nothing to do with water other than it is sometimes mounted on ships. http://defense-update.com/products/l/LRAD.htm [defense-update.com]

          The suggestion I made was referring to the possiblity that it could be used as an under-water torpedo defense. The pirates were using fast-attack boat
  • by tuomas_kaikkonen ( 843958 ) * on Wednesday November 29, 2006 @10:08PM (#17044162) Homepage
    To me the video seemed like two tubes that generated a derivation from Bernoulli effect.

    Some readers seem to mix up infra and ultra. Ultrasound is high frequency sounds.

    References:
    http://en.wikipedia.org/wiki/Bernoulli_Effect
    http://en.wikipedia.org/wiki/Ultrasound

  • Apparently the ants, spiders and ladybugs endured the trick just fine, but the fish didn't do so well due to lack of water.

    I'm sure there's a whale joke in there somewhere...

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