Forget electrons or photons: so uncool. A rather retro group at the University of Michigan has built a computer that runs on air.
The machine processes binary signals by sucking air out of a tube to represent a 0, or letting it back in to represent a 1. Pneumatic valves control the flow.
Each valve is operated by changing the air pressure in a small chamber below the air channel, separated from the circuit by a flexible impermeable membrane. Filling the lower chamber with air pushes the membrane upwards and closes the valve. Sucking the air out reopens the valve by forcing the membrane downwards, letting the signal cross the junction.
The researchers say they have been able to produce 2-bit, 3-bit, 4-bit and 8-bit microprocessors this way.
But why? The researchers admit that their device won't be breaking any speed records - although they suggest, rather plaintively, that making it a bit smaller could improve the clock speed.
The also accept that it isn't likely to have any practical application beyond microfluidics. But, they say, the fact that the required vacuum can be generated by a hand pump means it may be useful in developing countries.
Read more in Lab on a Chip.