Shrinking "laboratory" onto a computer chip.
The miniature laboratories can be used to separate mixtures into pure chemical components. Such separations, called capillary chromatography and capillary electrophoresis, frequently are used in clinical analyses of blood and tissue samples, medical research, and drug discovery. In standard chromatography, a solution to be separated is poured through a tube or column packed with various particles coated with a chemical compound. The various components of the solution are attracted to the particles with different affinity. As the mixture flows through the column, it separates into a series of zones, each containing a pure substance.
The miniature laboratories employ the same principle. The difference is in their size and the way they are made. Channels and microscopic "particles" are created using photolithography and chemical etching, the same technologies utilized to build semiconductors. The entire laboratory--with chemical reaction vessels the size of a speck of dust and chromatography columns the size of a human hair--is cut from a single piece of silicon, similar to the creation of a sculpture. Liquids are moved on the chip by voltage applied at the ends of the channels.
Despite their diminutive size, the laboratories on a chip can obtain accurate measurements with just a fraction of a drop of liquid. "Instead of using microliters of liquid, as is normally done, we use picoliters, volumes that area million times smaller," Regnier explains. "Using these tiny amounts of sample, measurements can still be made to within a few percent accuracy."
The mini-labs also differ from standard chromatographs because they contain no moving parts. Thus, they are much simpler and much less expensive to build than conventional laboratory equipment. "A standard liquid pumping system and column, for example, may cost $15,000, but a chip can be fabricated for $400, and we can line up 10 to 100 mini-laboratories on a single chip. That's the beauty of the microfabricated devices. In microfabrication, it's just as easy to create a large number of laboratories as it is to create just one, because they're all etched into the silicon chip at once as a single unit."
The new technology may be particularly useful in pharmaceutical laboratories, where scientists analyze thousands of natural and synthetic compounds in search of new drug candidates. Other applications may include clinical settings such as a doctor's office, where the miniature laboratory could be used by medical professionals to perform diagnostic procedures. For simple diagnostic procedures, lab oratories could be designed to work in a fashion similar to pregnancy test kits.
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|Title Annotation:||miniature laboratories on computer chip|
|Publication:||USA Today (Magazine)|
|Article Type:||Brief Article|
|Date:||Jun 1, 1998|
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