Beetle shell offers material solutions

An obscure species of beetle could teach industry how to produce brilliant white ultra-thin materials, according to a research team led by the

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The Cyphochilus beetle has a brilliant white shell. New research by the University of Exeter and Imerys Minerals and published today in Science, reveals the secret to this beetle’s appearance.

The Cyphochilus beetle has evolved its brilliant whiteness using a unique surface structure. At one 200th of a millimetre thick, its scales are ten times thinner than a human hair. Industrial mineral coatings, such as those used on high quality paper, plastics and in some paints, would need to be twice as thick to be as white. According to ISO accredited measurements for whiteness and brightness, the beetle is much whiter and brighter than milk and the average human tooth, which are both considerably thicker.

‘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,’ said Dr Pete Vukusic of the University of Exeter’s School of Physics. ‘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.’

Colour in nature and technology can be produced by pigmentation or by very regularly arranged layers or structures. Whiteness, however, is created through a random structure, which produces ‘scattering’ of all colours simultaneously.

Using electron microscope imaging, Dr Vukusic studied the beetle’s body, head and legs and found them to be covered in long flat scales, which have highly random internal 3D structures. These irregular internal forms are the key to its uniquely effective light scattering. By balancing the size of the structures with the spacing between them, they scatter white light far more efficiently than the fibres in white paper or the enamel on teeth.

Native to South-east Asia, it is believed that the beetle’s whiteness has evolved to mimic local white fungi as a form of camouflage.