Butterfly wing iridescence holds key to vapour technologies

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The physical structure and surface chemistry of the Morpho butterfly’s wings contain properties that could lead to applications including photonic security tags and industrial sensors, claim researchers in the UK and US.

Tree-like nanostructures on the scales of Morpho wings are known to be responsible for the butterfly’s metallic blue iridescence.

A new study, conducted by Exeter University in collaboration with General Electric (GE) Global Research Centre, University at Albany and Air Force Research Laboratory, found that vapour molecules adhere differently to the tops of these structures than to the bottom.

This selective response to vapour molecules is said to be the key to the range of possible bio-inspired technological applications.

The research, funded by the US Defense Advanced Research Projects Agency (DARPA), is detailed in PNAS.

GE’s Dr Radislav Potyrailo, principal investigator on the DARPA Program, said, ‘Our interdisciplinary team of physicists, chemists, biologist, and materials scientists was able to unveil the existence of surface polarity gradient on iridescent Morpho butterfly scales.

‘This discovery further allowed us to bring a multivariable perspective for vapour sensing, where selectivity is achieved within a single chemically graded nanostructured sensing unit, rather than from an array of separate sensors.’

‘Understanding iridescence in butterflies and moths has revolutionised our knowledge of natural photonics,’ said Exeter’s  Prof Pete Vukusic in a statement. ‘By using design ideas from nature we are able to work towards the development of applications in a range of different technologies. In this study the team discovered a new mechanism in photonic vapour sensing that demonstrates combined physical and chemical effects on the nanoscale.’