
Machine that Levitates Objects Using Sound [video] - justinmares
http://www.hardware-360.com/three-dimensional-mid-air-acoustic-manipulation/
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deletes
If we assume they want to hold objects with a size of half a centimeter, a
quick calculation shows they are using a sound frequency of 68000Hz.

-> 340m/s / 0.005m = 68000Hz.

If we limit the frequency to above human hearing range (>20000Hz) then maximum
size of objects held in this way would be about 1.7 centimeters.

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MarkPNeyer
i'd love to hear what it would sound like if you were in the room while this
thing levitated something like a golf ball.

i bet that becomes a new form of music.

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zerohp
The pressure wave would likely destroy your hearing because of the additional
energy that would be required to lift a more massive object like a golf ball.

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dustingetz
Maybe not. The bass at a dubstep show hits your chest really hard, I can
imagine it floating a golf ball. You can do some simple DSP to cancel out most
of the amplitude too

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minutetominute
Could this be used to create a 3D display? For example, when turned off, it's
just a pile of styrofoam pellets, but when on, it can use standing waves to
create shapes in midair?

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HCIdivision17
I will say yes merely to avoid being the guy without enough imagination.

But the technical hurdle is quite high. As chm notes, all you need to do is
generate a standing waveform that has enough nodes in the right configuration.
Which is fairly difficult: this is an exciting project, and has only _one_
node. (The extra nodes are higher order fringes and are noise.)

But, if you figure out how to generate a fringe pattern that happens to be
what you're looking for, well, you're made then! But that may be immensely
difficult to do.

But I'm not a signals guy, so there may be some powerful tricks 'n transforms
that make this a tractable problem.

So... Basically no, this far from being a display technology, but there's no
reason to think it couldn't be at some point in the future. Personally, it
could be useful as a 3D plotter, or something that displays a few spares
particles interacting (like an air traffic control radar map visualizer -
useless but cool).

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jluxenberg
What about rapidly moving an illuminated object? Tiny LED connected to tiny
battery?

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HCIdivision17
I'll raise you an induction coil and leave off the battery. Or a small LED
powered by a maser pointed down on the field. I mean, if you're gonna make
something like that, go all out!

(Fun experiment: stick some Christmas light bulbs in the rim of a disposable
bowl, fill it with a cup of water, and microwave it for a dozen seconds :)

Probably easier to just use a fluorescing material though. One might approach
it as an optimization, using a scanning light to illuminate the particles, but
the sound waves to keep the particle densities high where they need to be and
low where no illumination is needed. It would make the apparent hologram
easier to see through while maintaining brightness.

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ChrisNorstrom
Commercial Application Imagination Time:

Mix & combine foods, chemicals, and drugs without contaminating them or using
beakers or containers by floating them around the warehouse on tracks of sound
imiting assembly lines. I'd imagine a huge factory with minimal moving parts
and sterilized air where liquids are floated out and mixed. If you're afraid
the liquids will evaporate into the air while being mixed you can encase the
assembly line in Anti-microbial glass vents (or black ones that don't let UV
light through). Basically floating chemicals through really clean tubes
without touching the sides.

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HCIdivision17
I wonder if this would be a good technology for a pick-and-place robot for
circuits.

Obviously the palsy needs to be fixed, but assuming that's solvable, it would
be interesting to see it used as perfectly sterile tweezers.

Alternately, there seems to be some impressive vertical momentum imparted.
Perhaps it could be used to launch small components into the air to be caught
by another acoustic field, which does a more refined drop or transfer.

Or... Well, there's an awful lot of applications, really. Truly cool tech.*

* This isn't the first time a trick like this has been done, but it's the first I've seen with such control and dexterity.

Low frequency sound "halting" flow of water (illusion):
[http://www.youtube.com/watch?v=mODqQvlrgIQ](http://www.youtube.com/watch?v=mODqQvlrgIQ)

Non-Newtonian fluid on speaker:
[http://www.youtube.com/watch?v=3zoTKXXNQIU](http://www.youtube.com/watch?v=3zoTKXXNQIU)

Of course yesterday's article on General Fusion showing the power of a well
focused waveform:
[http://news.ycombinator.com/item?id=6996683](http://news.ycombinator.com/item?id=6996683)

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Someone
_" Well, there's an awful lot of applications, really."_

I doubt it. Firstly, how does one fix that 'palsy'?

Secondly, I wonder how much power this thing takes to lift those tiny objects
(what does a resistor weigh? Rounding up, it's maybe a tenth of a cubic
centimeter. Rounding up, its density is 10kg/l, so that's at most a gram). Low
efficiency can make lots of applications prohibitively expensive.

But cool tech? Certainly.

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HCIdivision17
I imagine that the palsy is the result of not tuning the node to match the
component perfectly. But it may also be subject to a theoretical limitation
due to what frequencies can be interfered with before the air stops behaving
properly; I assume there's plenty of control left for tuning, but it may just
not be possible. I am definitely out of my technical depth on that; may be fun
to look up papers on the topic, assuming few with paywalls.

And yes, it is likely _wildly_ inefficient. I could still see it being used as
a touchless guidance/placement device, but it would likely need a hellaciously
fast camera system to work in tandem as components stream between speaker
sets. (I'm referencing something like the system that rejects bad potato
chips, but with the ability to route/align components.)

Is there an application that needs touch-free interaction? I assume so, but
honestly can't think of one, let alone needing this level of control. It
definitely feels like a technology in search of an application (like
GorillaGlass).

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ColinWright
I've been watching this same story submitted over and over again - it's nice
to see it get some traction.

In case you're wondering, the other submissions have no comments, so I won't
link to them, even though the other sources may have more videos, more
commentary, or better explanations. I've decided not to do the cross-
referencing for a while.

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chisophugis
mikeselectricstuff did a hack playing around with this concept
<[http://youtu.be/qy1w6rTpC2g>](http://youtu.be/qy1w6rTpC2g>).

Not nearly as sophisticated as the linked post, but still pretty neat
(especially seeing how he messes around with it).

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lwan
<a href =
"[http://youtu.be/qy1w6rTpC2g></a>](http://youtu.be/qy1w6rTpC2g></a>)

No idea how to do links. Your link has an extra ">"

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lwan
[http://youtu.be/qy1w6rTpC2g](http://youtu.be/qy1w6rTpC2g)

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NatW
I wonder the maximum weight that could be theoretically lifted, the amount of
power to do it, and if/when it could e.g: negatively-impact ears or skin.

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adriand
I wonder if you can feel the waves with your hand. Presumably you can - anyone
have any idea what that feels like?

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chm
Sound waves are longitudinal waves of air pressures. What you feel is just the
bulk of molecules hitting your hand at different frequencies and positions.
The closest feeling I can imagine would be to immerse your hand in an
ultrasonic bath. I've done this multiple times as an undergrad, it's nothing
special. It feels like your hand is buzzing.

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gji
Not quite the same as an ultrasonic bath. This device creates standing waves,
so the antinodes (parts of the wave where the amplitude is 0) will not move.
I'm pretty sure the waves created by an ultrasonic cleaner are moving. If the
wavelength is large enough, you should be able to feel where there is
vibration and where there is none.

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chm
The locations where the amplitude is minimal (0) are called nodes. The
antinodes are where the displacement is maximum. Ultrasonic baths scan through
a frequency range so that the standing waves produced by the drivers move
around, hopefully covering the whole bath in one scan.

So yeah, the feeling would be similar, but not exactly the same, as you're
also in a different medium.

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crusso
It would be cool to see this used in medicine. Imagine using advanced imaging
and standing waves focused(dynamically, with the aid of the computer) on
arterial blockages that you wanted to clear.

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splike
Or use it to stop blood flow while operating in an area

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toomuchtodo
Did.....did we just suggest forcefields?

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diaz
Nice, after all this time watching all the history channel and other non-
exact-scientific documentaries like the Aliens and Ancient Egyptians and
others related that said they used the techonological power of the sound waves
to lift the stones is finally real and proven not impossible.

I wait for the day when it's finally proven they were advanced civilizations
or helped by aliens :D.

This could be extremelly useful, I'm excited for more news about this.

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SectioAurea
See also the Coral Castle legends in more recent times.

Would be extremely interesting if this worked on a macro scale. They are
floating nuts and bolts with a small desktop device.

I'm also curious about power draw/requirements.

Apparently they are using arrays of Langevin type sandwich transducers to
generate the ultrasound, of the type used for industrial cleaning applications
(example
[http://www.ipfonline.com/products/index/langevin_type_sandwi...](http://www.ipfonline.com/products/index/langevin_type_sandwich_transducers_for_ultrasonic_cleaners_1)).

What happens if you have an array 2x2 meters? Or 20x20? Does the wave have to
completely encompass the object to act on it, without exception? In that case
we may need to revisit the lower frequencies and attempt to move balloons,
etc. Some relation to the resonant frequency of the object being targeted may
be involved.

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jared314
This might be interesting for positioning radiation targets without support
structures. I wonder how well this would work at high-pressures or in liquids.

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sarreph
Would be a pretty cool way to put on an Iron Man suit.

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andrewflnr
Did I forget my physics, or do their diagrams actually show the particles
suspended at the anti-nodes, i.e. the high-pressure areas?

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Houshalter
Would the air around the object being levitated be trapped as well?

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eli_gottlieb
Excellent. How soon can I get it in a screwdriver form-factor?

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lhgaghl
DAE just watch Dune recently?

