Boffins chill chip with ion wind

Fan efficiency increased

By Tony Smith • Get more from this author

16th August 2007 04:00 GMT

Scientists at Indiana's Purdue University have worked out to significantly increase the efficiency of kit designed to keep toasty microprocessors cool by zapping the air above the chip with a thousand Volts.

Coolers work by pulling air across a chip's upper surface to draws heat away from it. Unfortunately, interactions between air molecules akin to the surface tension that allows water and other liquids to form drops means that molecules close to the chip's surface don't move and this reduces the air streams ability to carry away thermal energy.

The solution proposed by the Purdue engineering school team is to set up a potential difference of 1000V across the surface of the chip. This ionises the air molecules, allowing them to move and form what's termed an 'ionic wind'.

But whatever you call it, the flow of ions makes the air near the chip surface less 'sticky', boosting the thermal flow.

The team tested the process using two electrodes placed 1cm apart on either side of a CPU. With a 1000V potential difference applied across the electrodes and a standard cooling fan in place, the team found that they could cool the processor to 95°C - the fan alone could only bring it down to 140°C.

In boffin-speak, that's a 250 per cent increase in the system's heat-transfer co-efficient, the researchers said.

However, there's more work to be done: specifically, the team wants to get the crucial voltage down, essentially if the technique's to be made practical to use in real computers. The group has in mind a collection of micron-spaced electrodes, each pair sufficiently close to that a much smaller potential difference will generate the same ionic wind.