A Hokusai print without ink? Kyoto team figured it out

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KYOTO–Have you ever wondered how a morpho butterfly gets its stunning iridescent blue color?

How about the jewel beetle and its stand-out metallic sheen?

The secret is how light is reflected by microscopic voids on the surface of their bodies, known as “structural coloration.”

Following nature’s lead, researchers from Kyoto University have developed a method for creating full-color, fade-resistant images without the use of ink.

To produce the effect, Easan Sivaniah, a professor of materials science at the university’s Institute for Integrated Cell-Material Sciences, and his colleagues made microscopic cavities on plastic film used in bottles and put them in ascetic acid solution.

The interruption of light caused by the hollows on the surface produced structural coloration as a result, much like in nature.

The team said the research could lead to the development of low-cost printing technology, as no pigments are necessary, and the materials and reagents involved are cheaper than conventional methods that rely on pigmentation.

Masateru Ito, a researcher at the university’s Institute for Integrated Cell-Material Sciences, noted that one application would be anti-forgery technology for banknotes.

Details of the research project were published in British science journal Nature’s online edition on June 20.

The researchers confirmed that this method can create colors across the entire visible spectra, and that the shape and size of images can be adjusted.

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