Minature Wind, Big Results

As anyone who has driven by the wind tunnels at Moffett Field or the wind turbines in the Altamont Pass to the east can tell you, you have to think BIG when you think wind. Real big. Well, usually anyway

Which makes it even more amazing at what researchers have developed with a tiny "ionic wind engine". How small it it? Small enough to to be built on top of a computer chip. Millimeter size, in other words. Moreover, says Suresh Garimella, a professor of mechanical engineering at Purdue University who along with Timothy Fisher developed the tiny engine, the next step will be to reduce the size from millimeters to microns, or millionths of a meter.

So what can you do with such a tiny puff of wind? For one thing, it can used to cool computers and consumer electronics, letting them operate at lower voltages and to cool small hot spots. Experimental results have shown that the technology increased the "heat-transfer coefficient," which describes the cooling rate, by as much as 250 percent. When used in combination with a conventional fan, the wind device enhanced the fan's effectiveness by increasing airflow to the surface of a mock computer chip. The technology also could help engineers design thinner laptop computers that run cooler than today's machines.

"Other experimental cooling-enhancement approaches might give you a 40 percent or a 50 percent improvement," says Garimella. "A 250 percent improvement is quite unusual." He added that the new cooling technology could be introduced in computers within three years if researchers are able to miniaturize it and make the system rugged enough. Such cooling devices could be integrated into portable consumer electronics products such as cell phones.

Here's how it works: The device generates ions using electrodes placed near one another. The anode is positioned about 10 millimeters above the cathodes. When voltage was passed through the device, the negatively charged electrodes discharged electrons toward the positively charged anode. Along the way, the electrons collided with air molecules, producing positively charged ions, which were then attracted back toward the negatively charged electrodes, creating an "ionic wind." This breeze increased the airflow on the surface of the experimental chip. Researchers quantified the cooling effect with infrared imaging, which showed the technology reduced heating from about 60 degrees Celsius -- or 140 degrees Fahrenheit -- to about 35 degrees C, or 95 F.

Posted by Jon Erickson at 09:21 AM  Permalink