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Chemical analysis reduced to a wee chip.

Imagine an entire chemical analysis system compressed onto a single chip--a little lab to carry anywhere, dip into samples, and give instant readings.

Sounds like a Lilliputian fantasy. Then again, maybe not.

D. Jed Harrison and colleagues at the University of Alberta in Edmonton, have built a bite-sized electrophoresis system, which separates compounds based on their densities and electrical charges.

Using ordinary microlithography techniques, the researchers etched capillary-sized channels onto a centimeter-long glass chip. With this tiny electrophoresis lab, the researchers could distinguish six fluorescently labeled amino acids in as little as 4 seconds, with a high rate of accuracy and efficiency. Their report appears in the Aug. 13 Science.

Based on this prototype, the team says, "It will be possible to develop a complete, miniaturized, integrated system with sample pretreatment, separation, and detection on a 'chip.'"

While their chip itself is not a complete lab, it is a major part of a lab. Down the road, complete chip-sized labs will make possible improved sensors, giving instant readings on a sample's changing chemistry, says chemist Zhonghui Fan, a coauthor of the report.

Scientists could, for instance, use a chip-lab to control quality during drug manufacture, to track an ongoing chemical reaction, or even to monitor blood chemistry inside a person's body.

"This chip is unique for several reasons," Fan says. "It's small and fast. It's a complete integrated separation system on a single chip. And it has no moving parts, which makes it more accurate and reliable."

To fashion the chip, the group used acids to cut channels barely 10 micrometers deep into the glass wafer. After filling the capillaries with an amino acid-rich solution, they applied a strong electrical potential across the sample. The electrical forces both "pumped" the sample through the channels and teased out the various amino acids. The team found it could change the fluid's direction of flow by adjusting the voltage.

In recent years, scientists have built "micromachines" -- such as motors, pumps, and valves. But they haven't constructed complete, working mechanical systems. This chip, the researchers assert, demonstrates that whole, miniaturized systems can operate successfully, opening the door to automation on a microscopic scale.

"It will be several years before anyone makes a commercial device," Fan says, "but now we know it can be done."
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Title Annotation:miniaturized computer analysis technology
Author:Lipkin, Richard
Publication:Science News
Article Type:Brief Article
Date:Aug 14, 1993
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