Morpho butterfly wings inspire thermal imagers

Ashley N. Paddock, ashley.paddock@photonics.com

Mother Nature's 5 million year old butterfly design has led to the development of a bio-inspired sensor that is faster, smaller and more sensitive than today's thermal imaging devices.

Dr. Radislav A. Potyrailo and colleagues at GE Global Research, the technology development segment of General Electric Co., copied the microscopic design on the iridescent wings of the Morpho sulkowskyi butterfly to develop thermal imagers for more advanced industrial inspection, medical diagnostics and military applications. Their findings appeared online in Nature Photonics (doi: 10.1038/nphoton.2011.355).

“Decorating of Morpho scales with single-walled carbon nanotubes provides the ability to absorb more infrared light and to enhance the thermal response of our sensor nanostructures,” Potyrailo said. The new thermal imagers can sense temperature changes down to 0.02 °C at a response rate of 1/40 of a second.

Morpho butterfly scales doped with single-walled carbon nanotubes efficiently detect mid-wave infrared radiation as visible iridescence changes. The nanoscale pitch and extremely small thermal mass of these biological optical resonators provide outstanding response sensitivity and speed in heat-sink-free operation. Courtesy of Business Wire.

The sensors, which are in the early stages of development, will offer better image quality because they will enable smaller pixel sizes than are possible with conventional thermal detectors, he said. The size and power requirements for the devices also will be reduced because there is no need to thermally cool the sensors.

“Some existing thermal detectors do have good sensitivity and speed that we achieved, but they require thermal cooling or heat sinks,” Potyrailo said. “Upon further development of this sensor concept, the sensor speed and temperature sensitivity will be also improved using artificial photonic nanostructures.”

Thermal imaging is used in a variety of military, industrial and medical applications, ranging from thermal vision goggles to noninvasive inspection of industrial components to medical diagnostics. The new bio-inspired nanostructured system could enable broader application of thermal imaging by improving the manufacturability, image resolution, sensitivity and response time of new systems.

“Our new approach for thermal detection adds to the arsenal of other excellent techniques, which are also in their laboratory stage of development,” he said.

The new detection concept could be used in many applications where visual heat maps of imaged areas serve as a valuable condition indicator. For medical diagnostics, the imagers could better visualize inflammation in the body and more easily detect changes in a patient's health. To aid firefighters, the technology could be used for handheld devices that enhance safety in operational situations. The nanostructured system also could be used to improve public safety and homeland protection through thermal security surveillance, or to see things at night and during the day in much greater detail than before.

The discovery resulted from studies led by Potyrailo on the technological applications of photonic properties of the butterfly wing scales.

“Earlier, we worked with Morpho butterfly wings for vapor-response sensors,” he said. “In 2007, we decided to look at their thermal responses as well because of the very low thermal mass of these natural photonic nanostructures.”

The team is working toward fabricating the artificial photonic nanostructures to outperform natural Morpho structures in their thermal response. Commercial applications could reach the market within the next five years.