A synthetic material that mimics the qualities of an iridescent opal may have wide-reaching technological applications, its creators say. With the application of an electric current the material can rapidly change to any color of the spectrum, and the developers, who said they’re ready to sell the technology today, added that their ‘photonic ink’ (P-Ink) material could soon be used in electronic books or advertising displays [ZDNet].
The synthetic material can be likened to an opal, a mineral that owes its variety of colours to its layered structure: regions with a high refractive index, in which light travels slowly, are interleaved with regions with a low refractive index. Light waves with a wavelength – or colour – similar to that of the space between layers are scattered in a way that gives opal its iridescent sheen [New Scientist]. The synthetic material has a similarly layered structure, but with the addition of a little voltage the space between the layers swells or shrinks, allowing for fine-tuned control of what color of light the material scatters.
News of the invention was published in the journal Angewandte Chemie [subscription required], and its creators believe that it one-ups the current technologies being used in the first electronic books. Electronic inks are already used in commercial products such as Amazon’s Kindle reader. Most current technologies use an electric field to manipulate drops of oil or pigment particles. The presence or absence of a voltage makes pixels on the display appear light or dark, and most displays are confined to monochrome. P-Ink, however, can display any colour without using pigments [Nature News].
One of the researchers, Andre Arsenault, has founded a company called Opalux to develop and market the material. “Given the current switching speeds, an ideal first product may be something like full-colour electronic paper,” he says. Although a pulse of voltage is needed to shift the colour, maintaining it in a given state requires no energy at all. And because the material’s colour comes from the way it scatters light that falls on it, rather than emitting light like a conventional display, it could be perfectly readable in bright light [New Scientist].
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