On the Wings of a Butterfly

The wings of a butterfly attract our attention for their marvellous colours. Have you noticed how the colour in some butterfly wings change depending on observer's position? These colours and their changing behaviour is because of well defined patterns on the wings. These patterns are visible when observed through nano-scale viewing microscopes (Scanning Electron Microscopes or Atomic Force Microscopy etc.). The physics behind these colours is now well understood, a combination of reflection, refraction and diffraction. Unlike reflection and refraction, it is the principle of diffraction which depends on the size of different shapes on the wings.

Recently, researchers in Cambridge Nano-science Centre have not just replicated these butterfly wings at the nanoscale but have shown capacity to tune their behaviour by selectively altering the nanoscale shapes. They have done this by the bottom-up approach (link), making small objects and thin films one-at-a-time.

This approach followed by researchers helps to create even more beautiful colours (see image below, click to enlarge) and aids in confirming the earlier proposed mechanisms which produce the concoction of colours on the wings of a butterfly (link to article).

Reprinted by permission from Macmillan Publishers Ltd: Nature Nanotechnology (PUBLISHED ONLINE: 30 MAY 2010 | DOI: 10.1038/NNANO.2010.101), copyright 2010.