Winging It

Jan 1, 2008 12:00 PM

GE is attempting to replicate the unique properties of butterfly wings — those that allow them to shimmer colorfully — to determine if they can be applied to sensor detection technology. The company's goal is to devise next-generation “colorimetric” sensors that someday might be deployed to detect everything from airborne hazardous chemicals to spoiled meat inside of a deli package.

Microscopic structures on the butterfly wings “selectively respond to different vapors” in the air, says Radislav A. Potyrailo, principal scientist at GE's chemical and biological sensing laboratory. “You get very slight, small changes in color based on what vapor [the wing] is exposed to.”

If GE can replicate and manipulate the structures, which are about 100 times smaller than the width of a human hair, Potyrailo says they can be used to design extremely sensitive, long-lasting sensors that change color upon exposure to various airborne molecules. The sensors would revert to normal when the molecules are no longer present. Such gas sensors have the potential to be highly selective and able to detect multiple substances without false alarms. They also would not require a power source, Potyrailo says.

GE does not expect the research to bear fruit in the commerical product market for about five years because the work is still in the early stages. However, the company is optimistic, saying the butterfly-inspired sensors could spark broad demand in various market sectors, including security.

The work “could enable us to achieve a big step change [forward] in the performance” of chemical sensors, Potyrailo says, adding that the technology could be useful in developing new chemical sensors for Homeland security.

Doron Pely, a vice president at Homeland Security Research Corp., a market research firm headquartered in Washington, D.C., calls GE's effort intriguing, saying the security industry has been looking for autonomous and intelligent chemical sensors that can distinguish between various substances. “The ability [for a sensor] to say something like, ‘I smell oxygen and not nitrogen,' is unique,” he says. “If you can move away from giving very general indications of a threat to a specific threat, then you are in a very good place.”

GE is focusing on a relatively rare Morpho species of butterflies called Morpho sulkowskyi. Scales on the butterfly's wings are arrayed with microscopic structures shaped like tiny Christmas trees. Airborne molecules, depending upon size and configuration, interact with different “branches” of the tree-shaped structures, triggering color changes by altering how light is absorbed and reflected.

According to Potyrailo, GE has successfully tested the butterfly structures in the laboratory using a variety of common gases, observing more highly selective and acute performance than obtainable by many existing chemical sensors. The challenge now is to duplicate and refine the performance using man-made structures, he says.

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