Butterfly Wings Inspire Counterfeit-Proof Material

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  • Harvard researchers have taken inspiration from ‘colour-changing’ wings of a butterfly to develop an artificial photonic material that is difficult to recreate.
  • Researchers were inspired by the male Pierella luna butterfly, uses its wings to perform an advanced optical trick known as reverse colour diffraction in order to attract a mate.
  • Owing to the microstructure of its wings — made up of tiny scales curled slightly upward at the end to diffract light — the butterfly appears to change colour when it’s viewed from different angles.
  • They created a diffraction grating, to split white light into its individual wavelengths of colour and sends those colours travelling in different directions.
  • When the photonic material is viewed from one angle, it looks to be one colour, but from a different angle, the colour appears to change
  • The superthin, transparent material consists of an array of microscopic plates, or scales, that mimic those that make up the Pierella luna’s wing.
  • Though the material is fairly difficult to recreate, it could be used to make more secure banknotes or passports, it would lend these printed objects a so-called “optical signature.”
  • The ability to tune the material to specific wavelengths could also make it valuable for producers of solar cells or light—emitting diodes (LEDs).
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