Whiter Than White

January 2007 - New research by the University of Exeter and Imerys Minerals Ltd. published in Science has found that the shell of the little known Cyphochilus beetle could hold the answer to manufacture of brilliant white ultra-thin materials.

Researchers believe that the beetle's exceptionally white shell mimics white fungi found in its native South-east Asia and thus provides camouflage. The shell has a unique surface structure with scales ten times thinner than a human hair. The report points out that coatings currently used on products such as paper, plastics and paints would need to be twice as thick to achieve similar whiteness. The beetle's shell is significantly whiter and brighter than milk or average human tooth enamel.

Dr Pete Vukusic of the University of Exeter's School of Physics said:

"This kind of brilliant whiteness from such a thin sample is rare in nature. As soon as I saw it, every instinct told me that the beetle was something very special. In future, the paper we write on, the colour of our teeth and even the efficiency of the rapidly emerging new generation of white light sources will be significantly improved if technology can take and apply the design ideas we learn from this beetle."

The report explains that whether in nature or technology production of colour results from pigmentation or from a regularly layered structure. However, whiteness is created through a random structure involving all colours at the same time. Using electron microscope imaging, Dr Vukusic found that the body, head and legs of the Cyphochilus beetle were covered in long flat scales with highly random internal structures. By balancing the size of these structures with the intervening spaces, white light is scattered with exceptional efficiency.

The report gives other examples of Biomimicry developed in the last few years. Californian scientists have shown how geckos climb walls and stick to ceilings; findings that could improve manufactured adhesives. A German researcher has found that lotus leaves have tiny bumps that cause rain water to cleanse surface dirt. This has important applications for paint and easy-clean fibres. Dr Vukusic showed how butterflies emit fluorescent signals by absorbing and re-emitting ultra-violet light. This natural phenomenon has existed for 30 million years, but high emission light emitting diodes are under development using the same mechanism.