Tiny wind engines cool computers

The idea is to create a breeze that wafts over computer chipsMinuscule wind engines could help to take computing power to the next level, scientists believe.
US researchers have developed a prototype device that creates a "breeze" made up of charged particles, or ions, to cool computer chips.
The "ionic wind", the scientists say, will help to manage the heat generated by increasingly powerful, yet ever-shrinking devices.
The research is to be published in the Journal of Applied Physics.
As computers grow increasingly powerful, computer chips are becoming more and more densely packed with transistors, the basic building blocks of microprocessors.
Timothy Fisher, associate professor of mechanical engineering at Purdue University and an author on the paper, said: "In computers and electronics, power equals heat, so we need to find ways to manage the heat generated in more powerful laptops and handheld computers."
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Conventional cooling technologies using fans are limited because they can suffer from air-flow problems. As the spinning blades waft air over a chip, the molecules nearest to the chip can get stuck and remain stationary, hindering the cooling effect.
But the new experimental wind engine employs a different strategy.
The prototype, which is attached to a mock computer chip, works by shifting charged particles from one end of the device to the other. As a voltage is applied to the ionic engine, positively charged particles (ions) are produced, and are dragged towards a negatively charged wire (a cathode), forcing constant air movement.

The team found the prototype engine boosted cooling
The researchers said that when it was used in conjunction with a conventional fan, air molecules, rather than getting stuck, were dragged across the chip's surface boosting cooling.
The team said the device increased the cooling rate from a conventional fan by up to 250%.
Professor Suresh Garimella, from Purdue University who is a co-author of the paper, said: "Other experimental cooling-enhancement approaches might give you a 40% or a 50% improvement.
"A 250% improvement is quite unusual."
The researchers now need to miniaturise their prototype, making it 100 times smaller than its current size, which is a few millimetres.
Professor Garimella said that this would be crucial for applying the technology to the latest computers and consumer electronics.
If miniaturisation is successful, the team expects the device to be introduced into products within the next three years.
The research is a collaboration between Purdue University, in Indiana, and chip-makers Intel.