Toronto: that’s not the first city you would think of when discussing E-paper, but this city is leading the way in the use of photonic crystals for improved flexible device displays: (From technologyreview.com) Crystal light: Photonic crystals made out of silica beads (shown as gray balls) measuring 200 nanometers across are embedded in a spongy electroactive polymer and sandwiched between transparent electrodes. When a voltage is applied, an electrolyte fluid is drawn into the polymer composite, causing it to swell (shown as yellow in the middle image). This alters the spacing of the crystals, affecting which wavelengths of light they reflect. When the spacing is carefully controlled, the pixel can be made to reflect any color in the visible spectrum. Credit: Nature Photonics