E ink can be used on many of the same surfaces as regular ink. For example, e ink might be applied to a piece of thin plastic containing many small cells. The cells are connected to microelectronics in the sheet, and the ink covers the entire surface of the sheet. The microelectronics create a positive or negative charge in each of the capsules. A negative charge beneath a capsule causes the particles in the ink to go to the top of the capsule, covering its top surface and making it appear white. A positive charge attracts the particles to the bottom of the capsule, allowing the dark ink to show and making the capsule take on the color of the ink.
One obvious use of this technology is digital books. Digital books could be displayed with e ink, allowing readers to store many books on a single device while creating a reading experience that is very similar to reading regular ink printed on regular paper. E ink could also be used for newspaper subscriptions, displaying records and files in offices, or for a variety of other uses. An advantage of e ink displays over the backlit displays of cell phones, PDAs, and similar other electronic devices is that they consume much less energy because they require power only when the display is changed. In addition, they are easier on the human eye because backlighting strains the reader's eyes.