Smrt dust


New scientist last week reported a potential new development in 3D display technology. The idea is to form a dynamic three-dimensional display from flying pixels.

It’s a neat concept. Flyfire, under development at MIT, uses a coordinated fleet of mini helicopters as pixels which can rearrange themselves to reproduce the 3D effect.

“It’s like when Winnie the Pooh hits a beehive: a swarm of bees comes out and chases him while changing its configuration to resemble a beast. In Flyfire, each bee is essentially a pixel that emits colored light and reconfigures itself into different forms.”

At the moment, they can control a small squadron of 10 helicopters with reasonable precision, so the the current state of play is a long way from the animations shown on the New Scientist and Flyfire websites. There are a lot of obvious technical difficulties. A single collision between two pixels could lead to an aerial pile-up and seriously screw up your display, so it has to be foolproof. Still, it is a cool thing to try to do.

At the moment, the helicopters are quite big for pixels, fitting in the palm of the hand, which may actually be an advantage for use in public displays, which is where the developers see this technology finding a home. It’d look fantastic from a distance. But how about making the pixels smaller so that a screen fits into the home?

According to the Flyfire press release, the project is seen as a step towards smart dust. This is where I start to get wary. Smart dust is based on the idea that tiny autonomous devices will work together in an array, each with it’s own power source and internal computer control. In this case, it’d be tiny flying pixels, let’s say the size of the pixels on a TV screen- about a quarter of millimetre for the sake of argument.

Trying to make a flying or hovering device that small, you start to run into problems pretty quickly, which can’t be simply engineered around. Even if you seal the fleet of pixels in a transparent box to shield the pixel-dust from sudden gusts of wind or inquisitive pets, air still moves on the inside. You approach the scale where you have to consider the way air molecules move individually, as opposed to collectively.

If you sit still in the box, you won’t feel the slightest movement of air. Likewise, a football placed in the box won’t be blown around, it’ll just sit there. But at the molecular level, there’s an incredible amount of activity. Gas molecules move around in all directions and randomly crash into one another. We don’t feel it because the constant bombardment acts in all directions, so it averages out to nothing.

But at the small scale, very slight imbalances in the number of collisions on one side or the other mean that our dust is bumped and jostled around in all directions.

The motion is totally random and constant, so it’s not a case of correcting against a constant breeze. It’s the difference between standing still against a strong wind or balancing on a tightrope with tennis balls thrown at you randomly from every direction.

For there to be any point in making a pixel so small, you have to be able to control it’s position with a precision comparable to its size. The best you can ever hope to do is to limit the random motion to within a certain volume. There will be some movement whatever you do.

Creating some kind of propulsion system for the dust pixels is another challenge, since scaling down the helicopter isn’t as simple as just making smaller moving parts. The New Scientist article links to this more than slightly disturbing report about remote control of live beetles, in relation to possible biotech alternatives to the helicopter system. Presumably they could wear hats with lights on and take the role of the heli-pixels. The idea of a remote-controled swarm of luminous cyborg beetles is approximately as appealing as replacing my Mach 3 with a cheese grater. It’s not the same as the dust concept anyway.

You also need a power supply, some kind of internal control system and the light source too, crammed into an incredibly small volume. The thing to remember is that nanotechnology is not the same as miniaturisation, as the rules of engineering change at the small scale.

Flyfire is a cool idea. Whether it’s scalable, practical and cost effective is another matter, and time will tell. But shrinking the idea using some imaginary nanotechnology is in a whole other league of impracticality.


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Explore posts in the same categories: Explaining nano, Speculative technology

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2 Comments on “Smrt dust”

  1. martywalpole Says:

    Interesting, James. I have yet to watch a 3D film, just don’t to seem to have the time to Avatar.

    • James Hayton Says:

      I doubt it would ever be able to show something as complex as Avatar. Remember that every pixel would have to move to change the 3D effect. *If* flyfire works, there will be limits as to what it can do, and the speed with which it can do it.

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