Tiny Sensors Inspired By Butterfly Wings Could Improve Bomb Detection

Engineers in GE labs have built a penny-sized radio sensor that can detect the faintest traces of chemicals and explosives and needs only a tiny amount of power to operate. The device uses a special film a tenth the thickness of a human hair to spot the compounds. The team was inspired in their research by unique, jagged structures on the wings of Morpho butterflies that give them their iridescent color. (They applied data analytics developed for their bio-inspired Morpho light and temperature sensors to the new radio frequency (RF) bomb sensors.)

“Our sensor could be placed as a sticker inside of a cargo container on a ship or on packaging for shipped goods,” says Radislav Potyrailo, a chemical sensing principal scientist who is leading development of the detector at GE Global Research. “It’s a stick-it-and-forget-it kind of thing. This advance brings us closer to a future of ubiquitous testing of chemical explosives.”

The tiny device might be a game changer in detecting hazardous materials like chemical oxidizers and explosives, a process that today requires large and expensive equipment like spectrometers and chromatographs. Instead, the new sensor, which should cost a few cents to produce, is 300 times smaller and consumes 100 times less power than desktop detectors found at airports and other inspection areas.

The device uses a radio frequency identification (RFID) tag coated with an advanced chemical detection film. The scientists designed the film by pooling their knowledge of materials science, nanotechnology, chemistry and data analytics. 

Potyrailo, for example,has been studying the scales on the wings of Morpho butterflies for several years. These complex structures absorb and bend light and give the butterflies their trademark shimmering coats. He found that when chemical molecules lodge themselves in the scales on the wings, the structures cause their iridescence to change (see below). “We analyze optical spectra from our bio-inspired Morpho sensors and spectra coming from the RF sensors using the same methods,” Potyrailo says. “Light and radio waves are very similar, after all. They are just different portions of the electromagnetic radiation.”

Morpho butterfly wings change their natural color (A) after exposure to ethanol (top B) and toluene (bottom B). Image credit: GE Global Research

The detector is made of two parts: the RFID sensor tag and a battery-powered, cellphone-size handheld tag reader. Commuters will be familiar with the RFID tag component. It’s similar to the technology they stick on their windshield for automatic highway toll collection but without a battery.

The tag is composed of a flat, coiled antenna attached to a microchip in the center. To operate, the antenna harvests power from the reader when it is nearby. Layered on top of the antenna and chip is the special film. This film and sensor combination is designed to respond only to molecules or particles of explosives or oxidizers that are used to make improvised bombs.

The portable reader is hitting the tag with radio frequencies, just like light hitting the butterfly’s wing. When workers hold it up to the sensor tag, the radio frequency spectrum is predictably altered by the presence of hazardous materials trapped in the film. This radio spectrum response is picked up by the antenna and then transmitted back to the reader, which processes the data to let authorities know whether a dangerous substance is present and how much of it is around.

Potyrailo says the technology’s sensing range will expand into an assortment of applications in the future, including passive gas leaks, electrical insulation degradation and bacterial contamination detection.

Potyrailo’s group has been working on the detector for several years. They have partnered with a number of GE labs as well as the Technical Support Working Group (TSWG), a U.S. interagency program for research and development of counterterrorism measures. Their device is designed to meet tough requirements for field deployment on ships and in punishing environments.

“It’s a very attractive device - reliable, robust, cost-effective, low power and high performance,” Potyrailo says. “Chemical threats can be detected and quantified at very low levels with a single sensor, even improvised explosive devices—crazy devices made out of common grocery or pharmacy stuff —we can detect them.”