Speaker technology keeps circuits cool

Traditional methods of using fans and heat sinks are limited, and next-generation devices might be impossible without improved cooling technology. At Georgia Institute of Technology (www.gatech.edu),engineers have developed synthetic jet arrays that produce two to three times the cooling of a fan while using two-thirds less energy.

The jets resemble tiny speakers with electromagnetic or piezoelectric drivers vibrating a diaphragm at 100 to 200 Hz. This sucks air into a cavity and expels it, creating pulsating jets of air that can be precisely directed. Though the jets move 70% less air than fans of comparable size, the airflow contains tiny vortices, which make the flow turbulent. Turbulent air mixes more efficiently with ambient air, breaking up thermal boundary layers and increasing heat transfer. The jets can be scaled to suit applications and turned on and off to meet changing thermal demands.