There nanotechnology – that is, the control of matter on a nanometer scale, that is, a billionth of a meter – is not science fiction, rather, it is part of nature itself. An example? The butterfly Blue Morpho. This is a moth that lives in the forests of Central and South America whose wings are electric blue thanks to some nanostructures that cover them: the study of these nanostructures has allowed us to develop a method to produce anti-reflective lenses.
The color of the wings of the Blue Morpho
Many animals and plants get their colors from pigments, which absorb some wavelengths of light and reflect others. But natural pigments have their limits: in animals, for example, we find mostly brown, red or yellow pigments. Yet creatures like the blue Morpho, the peacock or certain beetles display very bright colors, such as the blue or the green, even though they don’t have pigments of those colors. So how do they do it?
The secret of the Blue Morpho lies in the dorsal part of its wings: these are covered by nanostructuressmall repetitive structures down to the nanometer level that interact with light. These structures create interference with sunlight and reflect only the blue component of the visible spectrumcreating that electric color we see. This phenomenon is called structural colorand it is the same that we find in peacock feathers or in iridescent beetles.
The fact that the wings have this color is not a coincidence, in fact they perform a very important function, helping the butterfly to regulate the temperature. The wings, in fact, absorb part of the light, transforming it into heat, allowing the Blue Morpho to warm up. This is essential for its survival, especially in the early hours of the morning, when it needs energy to fly and search for food. But that’s not all. That bright, iridescent color that fascinates us so much also has a defensive function: confuse predators. Its brightness and the continuous change of tone depending on the angle of observation make the butterfly more difficult to follow, thus discouraging attacks. In practice, the color of its wings is not only beautiful, but also a perfect defense system, the result of millions of years of evolution.
How did we get from the blue Morhpo wings to anti-reflective lenses?
Studying the wings of this butterfly, scientists have discovered that the nanostructures present on their surface can be replicate, with difficulty, artificially. Some modern anti-reflective lenses exploit the same principle: the surfaces of the lenses are treated with very thin layers, formed by nanostructures (usually silicon-based, the main element that makes up beach sand) based on the same principles as butterfly wings. These structures drastically reduce the unwanted reflections, that can disturb vision, and improve the transparency of the lenses, allowing more light to pass through. This technology has proven to be essential in fields such as precision optics, cameras, displays and even solar cells, where every ray of light counts.
