Machine that Levitates Objects Using Sound [video] | Hacker News Reader

Machine that Levitates Objects Using Sound [video]

hardware-360.com

95 pointsjustinmares41 comments

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.

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.

You could probably approximate the sound by taking an ultrasound recording from a room that exists like this right now and slowing it down.

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.

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

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?

Yes, if you have drivers (hardware, not software) that can produce the desired interference pattern. I would think a high driver density, large frequency range and high resolution would be needed. But I'm not an engineer, so...

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).

Could you run an FFT on the image you want to display as a starting point for figuring out what frequencies you need?

I always assume that you can figure out the needed FFT for a result, but having never actually tried, I have no idea if it's a fallacious assumption left over from working with lasers for a bit.

Some EE out there should have a strong opinion on the topic, might call up a friend about it.

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

Simpler: tiny glass sphere, with RGB lasers mounted on the base tracking it and making it glow with different colors and intensities in different positions.

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.

I'm not totally positive, but I think it depends on the object. You'll need to tune the arrays of speakers such that they generate some kind of 3D interference pattern that perfectly matches whatever you're trying to image.

So as seen in the video, you can get a cool stepped pyramid shape (when the particles are thrown into the air), but you'll have to be pretty smart about what kinds of images you'll be able to display.

Can someone prove me wrong? I'm speaking at a very elementary wave/particle physics standpoint.

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.

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

Non-Newtonian fluid on speaker: 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

"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.

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).

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.

mikeselectricstuff did a hack playing around with this concept <http://youtu.be/qy1w6rTpC2g>.

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

I was just going to post that. Mike is a man who knows his stuff.

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

http://youtu.be/qy1w6rTpC2g

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.

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

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.

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.

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.

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.

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

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

Nanobubbles [1] are already being studied for this very purpose. Drugs are packaged within small bubbles, and injected into the blood stream. Targeted drug delivery is performed by popping the bubbles using ultrasound waves from an external speaker.

[1] http://www3.imperial.ac.uk/newsandeventspggrp/imperialcolleg...

While not the same idea as yours, a device similar to the one in this video was created at Argonne National Lab with the intention of helping make pharmaceuticals. I included a video below.

https://www.youtube.com/watch?v=669AcEBpdsY

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.

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...).

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.

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

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

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

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

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

DAE just watch Dune recently?

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