A University of Southern California researcher who with his team won a prize last year for demonstrating a new way to create DNA microarrays has improved the technique to make it much more powerful.

DNA microarrays, also known as gene chips, are a basic tool for modern medicine and biology, allowing researchers to detect whether a certain message sequence is present or absent in a given sample.

Usually, these chips are made to order by specialty companies, using extremely expensive equipment. But the directional soundwave technique invented by the research group of Eun Sok Kim, a professor at the USC Viterbi School's Ming Hsieh department of electrical engineering, will potentially allow researchers to have their own gene chip making machines in their own labs.

The Kim group's machines consist of an array of quartets of ejectors, depressions in which small drops of DNA bases -- the genetic chemical letters A, T, C, and G -- sit on top of thin membranes that can be given electronic snaps by an activator.

The snap is directional and extremely precise, so that droplets emerge at exactly the same predetermined angle from the vertical. The paths from the four different ejectors converge at a single point about 2 millimeters above the quartet package, adhering there to the surface of a slide. For each snap, only one of the four ejectors fires.

Supply lines from four central reservoirs refill the injectors after each snap.

Construction of quartet array system, described as a "nozzleless, heatless, lensless" machine is a complex process Kim and his former students, Jae Wan Kwon, now of the University of Missouri/Columbia and Sanat Kamal-Buhl, now of Intel, first described in an April 2006 paper in the IEEE Transactions on Automation Science and Engineering paper.

That paper won the journal's "Best New Application Paper Award" for 2006, based on the criteria of " technical merit, originali
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Contact: Eric Mankin
mankin@usc.edu
213-821-1887
University of Southern California
25-Apr-2007