Fan club

Some of us may not be able to see the world in a grain of sand, but a team of researchers has seen a way to make a fan, as small as a sand granule, which may someday replace much larger counterparts to cool computers.

Victor Bright, a professor of mechanical engineering at the University of Colorado, and two graduate students have built an eight-bladed fan on a silicon chip. Resembling a pinwheel, the device is so tiny that an array of 300 fits in a square inch. Each blade measures approximately one-half of a millimeter in length. The blades are connected to a tiny motor with silicon strips as hinges. Graduate student Paul Kladitis positioned each blade with minuscule drops of solder, while Ryan Linderman, another graduate student, developed the 180-rpm motor that turns the blades. The surface tension of the molten solder lifts the blades, which adhere to a small square of gold on either side of each hinge.

DARPA and the Air Force Research Laboratory are sponsoring the research for a project to develop soldering technology for assembling MEMS. The university research team presented a technical paper on the microfan at a MEMS conference hosted by the Institute of Electrical and Electronics Engineers in Interlaken, Switzerland, in January.

Although more work needs to be done, using arrays of the MEMS devices to dissipate heat in computers is just one possible application. Bright originally wanted to create a fan tiny enough to pump or mix gases in microfluidic devices such as chemical and biological sensors.

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