Alchemist's Ink

What alchemy makes images on paper move? The secret, Jerome Rubin explains, in in the ink ...

What alchemy makes images on paper move? The secret, Jerome Rubin explains, is in the ink: "an ink that will enable you to turn any surface you coat it on--paper, plastic, fabric--into the equivalent of a computer screen.

"Imagine a huge number of microcapsules," he says, "maybe 40 microns in diameter, each half-filled with tiny particles of titanium dioxide, which are white, and half-filled with dye--black, blue, whatever. Then you have an electric charge on the surface, provided, typically, by a thin film transistor. The electric charge rotates the capsules, depending on whether it is positive or negative. Normally the white sides are up and you have what looks like a piece of white paper. When a new charge draws the black sides to the surface, you get an image, a pattern of letters and drawings.

"The tricky thing about developing true electronic paper is developing a flexible back-plane--which would probably sit on a piece of plastic about the thickness of a sheet of plastic wrap. Some coating might be necessary to protect the ink, but the whole thing probably wouldn't be much thicker than a piece of coated paper in a magazine.

"An electronic book with electronic paper would have multiple sheets, 40 or 50, so you could read multiple pages and flip around. Inside the spine, you'd have a tiny microprocessor that would deliver instructions to the separate pages. You could receive the texts either over the Net or by wireless--of course, the Net will probably be wireless in 10 years, anyway--or you might have some flash memory to slip into the spine of the book. That way you can go on a holiday with 50 books loaded onto your card."

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