Unusually White Beetle Gives Scientists Bright Ideas

An obscure species of beetle could teach scientists how to produce brilliant white ultrathin materials and more efficient white light sources, according to a research team studying the insect.

Scientists are expecting the beetle's whiteness to be replicated in synthetic materials and applied to many technological applications. (Images courtesy of P. Vukusic, University of Exeter)

The Cyphochilus beetle has a highly unusual brilliant white shell. New research by the University of Exeter and Imerys Minerals Ltd. and published Jan. 19 in the journal Science reveals the secret to this beetle's unique appearance.

The beetle evolved its brilliant whiteness using a unique surface structure. At one 200th of a millimeter thick, its scales are 10 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.

The Cyphochilus beetle's brillant whiteness could help researchers develop bright white ultrathin materials and more efficient white light sources.

"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 Pete Vukusic of the University of Exeter's School of Physics. "In future, the paper we write on, the color 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 whiteness of Cyphochilus beetles sharply contrasts with the colored hues of scarab and weevil beetles.

Color in both 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 colors simultaneously.

Vukusic's team used techniques such as optical microscopy, laser analysis and spectrometry to study the insect. Using electron microscope imaging, Vukusic studied the beetle's body, head and legs and found them to be covered in long flat scales, which have highly random internal 3-D 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 fibers in white paper or the enamel on teeth.

Native to Southeast Asia, it is believed that the beetle's whiteness evolved to mimic local white fungi as a form of camouflage.

The whiteness of Cyphochilus scales is generated by the random structures that make up the scales interiors.

This is not the first time Vukusic has turned to designs in nature as a way of improving man-made photonic products. In 2005, he showed how butterflies give out fluorescent signals by absorbing and reemitting ultraviolet light. This technology has been in place in nature for 30 million years, but scientists are just now developing high-emission LEDs, which work in the same way. He also worked with cosmetics company L'Oréal to develop a pigment-free photonic makeup based on mimicking butterfly scales.

For more information, visit: www.exeter.ac.uk