The father of chaos theory, Edward Lorenz, once wondered whether the flap of a butterfly’s wings in Brazil could set off a tornado in Texas. He called the possibility the Butterfly Effect.
Scientists at GE Global Research have also butterflies on their minds. But rather than studying tornadoes in Texas, they are looking the wings themselves and their chaos of colors.
Radislav Potyrailo, the principal scientist who leads the program, and his team are using the science of the very small, nanotechnology, and the science of light, called photonics, to mimic the properties of the jagged, forest-like scales on the wings of butterflies from the Morpho genus. The scales’ complex interplay with light gives the wings their vibrant blue and green sheen.
Top and above: Scientists at GE Global Research imaged Morpho butterfly wings with an electron scanning microscope. Image credit: GE Global Research
Researchers have observed that Morpho wings change their color when they come into contact with heat, gases and chemicals. Potyrailo’s team wants to know why and use their findings to develop fast, ultra-sensitive thermal and chemical imaging sensors. They could have applications in night vision goggles, super-sensitive surveillance cameras, handheld and wearable medical diagnostic devices, and even everyday objects.
Morpho butterfly wings change their natural color (A) after exposure to ethanol (top B) and toluene (bottom B). Image credit: GE Global Research
The idea of imitating nature and cribbing its most successful ideas is called biomimetics. Swiss engineer George de Mestro invented Velcro after his dog came home covered with thistle burrs, Speedo learned from sharkskin to make faster swimsuits, and chemical companies designed self-cleaning paint after studying lotus leaves.
Image credit: GE Global Research
The GE team started by looking at Morpho wings with a powerful electron scanning microscope. They saw a layer of tiny scales just tens of micrometers across. In turn, each of the scales had arrays of ridges a few hundred nanometers wide (see above). These complex structures absorb and bend light and give the butterflies their trademark shimmering coat.
The team found that when infrared radiation, i.e. heat, hits the wing, the nanostructures on the wing warm up and expand, causing iridescence and color to change.
Morpho butterfly wings could inspire the next generation of thermal imaging sensors. Image credit: GE Global Research
Working with DARPA, the Pentagon’s advanced research projects arm, the scientists discovered that the nanostructures were also behind the Morpho’s “extraordinary vapor-response selectivity,” says Potyrailo.
Detectors based on the team’s research could one day they help doctors create visual heat maps of internal organs, assess wound healing, test food and water safety, monitor power plant emissions and detect explosives.
“These future nano-fabricated, bio-inspired sensors should provide an enhanced response to heat and chemicals,” Potyrailo says. “We could use them to detect smaller levels of medical, environmental, or homeland security problems, and act on these early signs.”
He says that “depending on application scenarios, the sensors could be stationary or mobile, and inside handheld and wearable devices. They could be woven into sports apparel or embedded in industrial protective clothing.”
Scientists at GE Global Research discovered that the nanostructures on the wing scales of Morpho butterflies have excellent sensing capabilities. They could allow them to build sensors that can detect heat and also as many as 1,000 different chemicals. Image credit: GE Global Research
Meanwhile, the team is already improving on evolution. They added tiny carbon nanotubes to the wings, and were able to increase the amount of radiation the wings can absorb and increase their heat sensitivity.
“This new class of thermal imaging sensors promises significant improvements over existing detectors in their image quality, speed, sensitivity, size, power requirements and cost,” Potyrailo says.
He and his team are starting to untangle the chaos of colors.
The scales’ complex interplay with light gives the wings their iridescent sheen. Image credit: GE Global Research