As tiny chips and electronic subsystems in portable devices get more powerful, they also run hotter. Fans and ventilation systems offer some relief, but researchers recognize that it's time for the next generation in cooling techniques. A Purdue University research team, backed by funding from the National Science Foundation, has developed a miniature cooling system that could be ideal for cooling notebook computers, cell phones, and smaller devices. Unlike some of the prototype liquid-based cooling systems being produced, the Purdue team's technology generates tiny breezes with nary a fanor the whir of onein earshot or sight.
"The exciting attribute of this work is that it has the potential to provide heat removal rates that are similar to those for liquid cooling, but accomplishes this with air and in a very compact volume," says Suresh Garimella, a professor of mechanical engineering at Purdue, in West Lafayette, Indiana.
The miniature cooling systems are somewhat similar to the quiet fans that circulate air in homes, but the Purdue team's devices are only a few microns (millionths of a meter) wide. They use electrodes built from carbon nanotubes that are just five nanometers (billionths of a meter) across at the tip. The low-voltage carbon nanotube electrodes emit electrons and create an ionizing effect. Clouds of electrons get "pumped forward" by changes in the voltage that the electrodes emit, producing a wave of tiny breezes. Despite the obvious fan analogies, the research team prefers to call the technology "nano-lightning."
Two research representatives from Purdue, Daniel J. Schlitz and Vishal Singhal, have started a company called Thorrn Micro Technologies Inc., to commercialize the technology. The team has also filed for a patent.
"Using liquid to cool electronic circuits poses many challenges," says Garimella, "and industry would rather develop new cooling methods that use air."