digital ink

A new technology currently under development, digital ink will theoretically make it possible to create electronic books that have the look and feel of today's dead tree versions. The concept involves using "pixels" that are actually magnetically-flippable capsules--black on one side, white on the other--that can be changed by electrical impulses. The technology is still in its infancy, and has only been used for things like window signs so far...but it is expected to be in general public use within several years at most.

Another technology currently being researched for digital ink uses titanium dioxide chips suspended in colored opaque oil.
This is encapsulated in tiny spheres: under an electric field, the titanium dioxide chips move to the sphere surface and make it white. When the electric field is removed, the color of the oil shows.

digital ink technology, when coupled with flexible circuitry, forms digital paper or E-paper.

Digital (or as it is more popularly known, electronic) ink combines the strengths of paper with the strengths of electronic displays, while reducing, and in some cases eliminating, their respective weaknesses.

Paper is easy to read, inexpensive, and malleable-- but static. Electronic displays, on the other hand, can change their content as needed. Currently, however, electronic display technology is hard on the eyes, and flat-panel displays are fragile, expensive, and consume large amounts of power.

E-ink is made up of very tiny microcapsules filled with negatively charged pigment chips suspended in a liquid. The ink is sandwiched between thin, flexible electrodes. When the top electrode has a positive charge, the pigment chips are attracted to the top of each microcapsule, making them appear lighter by reflecting ambient light. When the charge is reversed, the chips are repelled, making the capsules look dark.

The text created requires power only when the display changes. This is called bi-stable behavior, and means that e-ink-based displays draw very little power compared to other display technologies, which must be constantly refreshed to maintain their image.