Miniature sleuth searches for toxins.

• Position: Detection - Portable chip-size detection system developed at Purdue University

A portable, chip-size version of a detection system that is commonly used by industry and law enforcement to identify everything from agricultural toxins to DNA has been created by researchers at Purdue University, West Lafayette, Ind. The miniature detector could move certain types of testing from the lab into the field, saving time and money while increasing security.

"Now we have a way of putting all of the critical components on one wafer," says Timothy D. Sands, the Basil S. Turner Professor of Engineering in the School of Materials Engineering and the School of Electrical and Computer Engineering. "It's much the same in concept as going from separate transistors to an integrated circuit that includes many transistors on a single chip."

The traditional fluorescence detection system works by attaching a fluorescent dye to specific molecules in a substance and then shining a laser onto the substance. The laser light is absorbed by the dyed molecules, causing them to emit a certain color, which is picked up by a sensor. The detection work normally is done using bulky, stationary equipment in a laboratory. The new device, however, fits on a centimeter-wide chip, promising the development of miniature...