P-Ink - Billboards inspired by Butterflies

Researchers in Toronto have developed a new form of display inspired by butterflies, they call it P-ink.

Most displays today, whether that are conventional TV's, LCDs or big LED billboards work by emitting light. This is great at night but during the day they tend to look dull and washed out because the daylight is so strong. Glowing also requires a lot of energy.

Dr Andre Arsenault and colleagues at Opalux in Toronto have come up with a neat solution. Many iridescent butterflies and beetles produce really bright colours without using pigments at all. They rely on a phenomenon called structural colour - they have tiny repeated structures, about the wavelength of light in size, which produce colour in a similar way to reflections in a CD, a layer of oil on water or in an opal.

Opalux are using a similar effect by putting lots of tiny silica beads in a polymer. This makes colours in the same way as the beetle, but the clever bit is that by changing the distance between the beads by using a voltage, they can changes the colour that the beads reflect - and so change the colour that you see. By building up a grid of pixels like this and using a computer to calculate the distances, you can make a display. So far, the refresh rate isn't good enough to use for video, but it works well enough for billboards or e-books.