Supercomputing May Require Bugs

Lynn M. Savage

If you were looking for a diamond in the rough, would you think to look on the backs of beetles? One group of researchers did, and found a photonic gem worth taking to the bank.

The ultimate photonic crystal would manipulate light so efficiently that high-speed computers operating purely on photons could become reality. The perfect photonic crystal should have the same overall structure as that formed by carbon atoms in a diamond, just not as tightly packed together. No such man-made crystal operating at visible wavelengths exists yet because the technical challenges have been too great.

Nature, however, as any biomimeticist will tell you, has made many structures unmatched by human engineers, and so it has apparently devised a photonic crystal in the form of the scales of the beetle Lamprocyphus augustus (pictured right).

Courtesy of Michael H. Bartl, University of Utah. Beetle image courtesy of Jeremy W. Galusha, University of Utah.

The insect, part of the weevil family, has green iridescent scales on its exoskeleton. About 100 μm wide by 200 μm long, the scales have one very important aspect: They appear iridescent from any angle. The researchers used a scanning electron microscope to examine the scales and found that each has a 3-D structure similar to diamond. The difference is that, instead of carbon atoms, the scales use chitin, a polymeric fingernail-like substance that forms the insect’s exoskeleton.

Importantly, especially for future research, the investigators found that individual scales are not continuous crystals, but include up to 200 separate pieces of chitin that have the same basic crystal structure but which are oriented such that each piece reflects a slightly different green wavelength.

The researchers — representing the University of Utah in Salt Lake City, Brigham Young University in Provo, Utah, and IBM’s Almaden Research Center in San Jose, Calif. — published their findings in a “Rapid Communications” by Physical Review E on May 29, 2008.