Ideas for new surfaces from studies of rice leaves and butterfly wings

Studying the surface textures of rice leaves and butterfly wings up close has given insight into how the surfaces of products can be improved.

In a study funded by the National Science Foundation and published in the journal Soft Matter, engineers from Ohio State University report a 15 percent increase in the dust which can be removed from a surface mimicking the Giant Blue Morpho butterfly’s wings from an ordinary flat surface. What cannot be seen by the naked eye is that the wing is made of overlapping ’tiles’, almost like a roof , allowing it to self-clean more easily. Such a function is vital in nature because build up of dirt would inhibit flying and would mask the distinctive patterns on the bright blue wings by which mates recognise each other.

The rice leaves provided a very different type of surface environment; a waxy coating with grooves and bumps all designed to push rainwater down and off the tip of a leaf. In an experiment to observe the effect of the surface on water flow, small plastic pipes were coated with plastic nanoparticles to mimic the type of surface texture, and the reduction in pressure of the fluid noted. The rice leaf type covering reduced the pressure by 26 percent – second only to a coating that mirrored a shark’s skin.

These finding could have a real impact where cleanliness or reduced friction is paramount. A coating similar to the butterfly’s wing could be used in the development of medical equipment in an attempt to prevent bacteria growth on a surface, while the rice leaf texture could be one way to reduce friction in industrial pipelines or tubing.