Are Inimitable Nano Spirals Future of Security and Encryption?

Holograms greatly enhanced security on credit cards but counterfeiters soon found a way to copy them. Recently developed nano-spirals promise to be what holograms couldn't - remain copy-proof.

Researchers at Vanderbilt University fabricated nano-spirals with unique optical characteristics that can be difficult to replicate. While spirals are not new, those produced by university's team have contiguous arms and are smaller than earlier designs.

"They are certainly smaller than any of the spirals we've found reported in the scientific literature," said Roderick Davidson II, a doctoral student who studied spirals' optical behavior.

Davidson and his team fabricated spirals of gold that can emit blue light when illuminated by infrared light. To put it simply, electrons in the arms of the spiral smaller in width than wavelength of light, gain energy and move down the spiral, emitting light in high-energy spectrum. Researchers also found discovered other unique optical behaviors when spirals were illuminated by polarized light.

Such properties make spirals highly customizable as a unique signature for use on objects that are susceptible to unauthorized replication or required tracking.

"If nano-spirals were embedded in a credit card or identification card, they could be detected by a device comparable to a barcode reader," said Richard Haglund, a professor of physics who directed the research.

For their experiment, researchers made spirals from gold on glass but said other precious metals can be used in small quantities to make spirals on plastic or even paper.