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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.

“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.

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Top image: An example of a wireless, battery-free RFID sensor tag for detection of chemicals such as explosives and oxidizers at very low concentrations. These sensors could provide advanced chemical and explosives detection at shipping ports. The new sensor is using data analytics developed for their bio-inspired Morpho light and temperature sensors to sniff out dangerous chemicals Above: Heat and chemicals can alter how the jagged structures on Morpho wings reflect light and change butterfly’s color. Image credit: GE Global Research

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 theirtrademark 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.“

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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. 

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The GE Global Research team
behind the RFID sensor. Potyrailo is second from the left. Image credit: GE Global Research

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.”