Oil and water drive display

Researchers from Extreme Photonix and the University of Cincinnati have combined water and oil in a technology that promises bright, energy-efficient displays.

The researchers' prototype is a combination of the researchers' previously developed lightwave coupling technology, which channels violet light from within a sheet of plastic or pane of glass to individual pixels, and an electrowetting device that turns each pixel on and off.

The electrowetting device contains water and oil that compete for placement on a surface. The surface is hydrophobic, or water repellent, which leaves the oil covering the surface. This is the pixels' "on" state. Applying a voltage to the surface attracts the water, which displaces the oil to turn the pixel off. The pixel can switch on or off in ten thousandths of a second, which is fast enough for video.

The oil film contains lumophores, or organic molecules, that emit red, green and blue light when they absorb violet light provided by light-emitting diodes.

The method could be used in signs, to make bright energy-efficient displays in cell phones, handheld computers and laptops, and eventually in screens designed to provide a lower-cost alternative to high-definition television.

The researchers method could be used in signs within two years. The method could be used in practical computer displays in five to ten years, according to the researchers. The work appeared in the January 3, 2005 issue of Applied Physics Letters.