Electrowetting to Make Real Paper Act Like Displays

University of CincinnatiWired: Electrical Engineering professor Andrew Steckl and his team at the University of Cincinnati is working on making real paper act like a display. The technology he is using is electrowetting. What is electrowetting? Electrowetting is a microfluidic phenomenon that modifies a liquid’s surface tension on a substrate using a voltage. The voltage modifies a hydrophobic surface to become hydrophilic. Liquavista:

Without a voltage, the colored oil forms a continuous film and the color is visible to the consumer. When a voltage is applied to the display pixel the oil is displaced and the pixel becomes transparent.

Current prototypes have been limited to about 8.5 inches but theoretically there is no limit to how large a display based on electrowetting technology can get. Electrowetting-based displays are scheduled to hit commercial production in 2011.

Companies like Plastic Logic and Liquavista have used electrowetting to make prototype displays but use glass or plastic substrates. Steckl and his team is using plain paper. The benefits of paper over glass or plastic are substantial: there is greater flexibility and cost is lower. Steckl:

Nothing looks better than paper for reading. We hope to have something that would actually look like paper but behave like a computer monitor in terms of its ability to store information. We would have something that is very cheap, very fast, full-color and at the end of the day or the end of the week, you could pitch it into the trash.

Let’s hope not. I would like to see additional technology that allows for reuse of something like a real electronic paper.

Steckl and Duk Young Kim, a University of Cincinnati’s Nanoelectronics Laboratory graduate student presented Kim’s doctoral dissertation in the October issue of the American Chemical Society’s ACS Applied Materials and Interfaces journal. Kim wrote:

One of the main goals of e-paper is to replicate the look and feel of actual ink on paper. We have, therefore, investigated the use of paper as the perfect substrate for EW devices to accomplish e-paper on paper.

Wired:

For maximum performance, the process involves a specific grade of paper with a particular surface coating, roughness, thickness and water uptake and a carefully controlled contact angle at which the electrowetted material is applied to the paper support. Electrowetted glass e-readers may appear sometime next year, but you’re unlikely to see disposable paper screens in newspapers or posters for at least three to five years.

Although paper-based electrowetting displays might be years away, glass-based electrowetting display products can show up on e-readers. Electrowetting displays consume less power and seem to be compatible with existing LCD manufacturing processes, which is key to getting to volume production and lower prices. One main benefit of electrowetting is its fast response time allowing for long battery life for an e-reader as well as being able to show video, without flicker.