Darpa’s Butterfly-Inspired Sensors Light Up at Chemical Threats

The Pentagon's got a new game plan to detect deadly chemical threats: tiny, iridescent sensors that are designed to mimic one of nature's most colorful creatures: Butterflies.

It's the latest in a series of Darpa-funded efforts to use insects to spot weapons. Last year, the agency tapped researchers at Agiltron Corporation to implant larvae with micromechanical chemical sensors. In 2005, Darpa-backed scientists started training honey bees to become bomb sniffers.

This time, Darpa's interested in the chemical-sensing talents of butterflies. The agency's awarded $6.3 million to a consortium, led by GE Global Research, that'll develop synthetic versions of the nanostructures found on the scales of butterfly wings.

The project's lead researcher, Dr. Radislav Potyrailo, likens the nanostructures on the butterfly wing scales, which each measure around 50 by 100 microns, to "tiles on a roof." The science of chemical response behind the structures is based on photonics. The wings of Morpho butterflies change spectral reflectivity depending on the exposure of the scales to different vapors. As Potyrailo and his team write in a 2007 paper, published in Nature Photonics, "this optical response dramatically outperforms that of existing nano-engineered photonic sensors."

"This is a fundamentally different approach," he tells Danger Room. "Existing sensors can measure individual gases in the environment, but they suffer, big time, from interferences. This approach overcomes that hurdle."

A single sensor would be tailored to detect certain types of chemical agents or explosives, and do so without hindrance from other chemicals, airborne molecules or even humidity. Water molecules, Potyrailo points out, can overload a dangerous gas that's sparsely distributed but "is still able to have actionable effects in a military setting." And, much like their biological inspiration, the sensors would do the job with remarkable specificity.

"It would be science fiction to say ‘here is my sensor, it can selectively detect 1,000 different chemicals'," he says. "But what we're saying is that we can detect and distinguish between several important chemicals - without making mistakes, without false responses."

At around 1 x 1 cm apiece, the sensors are also small enough to be attached to clothing, installed in buildings or deployed "like confetti" over widespread regions. And they'd have helpful civilian uses, as well, from food safety and water purification tests to emissions monitoring at power plants. So be careful, the next time you swat an insect. It just might save your skin.

Photo: GE Global Research


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