Electronic Design

Micro Lab Senses, Analyzes Liquids And Gases

Scientists at the Department of Energy's Sandia National Laboratory, Livermore, Calif., are developing a powerful handheld chemical-analysis device. As part of an integrated micro chem-lab system, the compact instrument will analyze liquid and gas mixtures. The system will offer a speedy, sensitive alternative to conventional chemical-analysis techniques.

Researchers were able to exhibit the efficiency of the device by examining a compound of explosives. Components are separated via a process called chromatography, which produces a kind of chemical trademark. Through this procedure, the mixture is carried through separation channels containing diverse substances. As these materials retain constituents to varying degrees, they show up consecutively in groups at the channel's end.

A portion of the original mixture is stored in a reservoir. Extracting from this repository, the system dispenses a tiny bead—0.10 nl—to channels thinner than a strand of human hair. Seconds later, a small monitor reveals the name and quantity of the components. Compounds are detected at the parts-per-billion level.

Referred to as a "lab-on-a-chip," this device features a compact power source and solid-state relays that regulate and switch energy derived from camera batteries. It also includes built-in lasers and photodiodes that are manufactured on a bit of semiconductor tiny enough to fit on a pencil eraser (see the figure). These are capable of reading results in each of three channels. An internal microprocessor then analyzes the information and forces the division. A keypad guides users through a list of instructions, allowing them to program the microprocessor.

Through further investigation, scientists anticipate that chemical analysis on a chip will become both affordable and far reaching. Researchers also can imagine automated field-portable systems able to compute outcomes in real time. Applications would include testing foods, finding land mines, and assessing environmental conditions.

For more information, call (925) 294-2932, or visit www.sandia.gov.

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