A Canadian start-up has developed a new form of electronic ink that changes colour according to the applied voltage. Displays using the ink, called P-ink, are like paper in that they rely on reflected light.

P-Ink makes use of photonic crystals, known confusingly as PCs, that can be used to modulate the passage of light rather as semiconductors like silicon are used in electronics. PCs occur naturally and causes some of the light effects in opals.

The P-ink from Toronto-based Opalux uses a synthetic opal comprising crystals that stretch or shrink with the applied voltage so that they reflects different colours.

Opalux says it can be tuned to the entire visible spectrum and requires " minimal" power when the image is static. Emerging e-paper displays using technology from the US company E-ink require no power when the image is static.

Chief technology officer Andre Arsenault said in an email that P-Ink can match the resolution of LCD displays. "The switching speed is not sufficient for video and may not be for a while. [But it is] sufficient for e-books and e-paper."

P-ink will initially be targeted for use in large information and advertising displays. But Arsenault says this is because, "unlike the great majority of display technologies", it can be used in large sheets; but it can also be used in small displays.