Many publications have online editions nowadays, but taking your laptop to bed is just not quite as cozy as snuggling up with a magazine or a good book. Engineers are working on a solution: electronic displays that look and feel like a sheet of paper. In today's Proceedings of the National Academy of Sciences USA, researchers from Bell Labs and E Ink Corporation describe a promising plastic prototype. It cannot display much more than a few words, but it is as thin as cardboard and bends like real paper.

The 5-by-5-inch plastic sheet carries 256 organic transistors, each of which can switch the color of a pixel roughly the size of a key on a computer keyboard. Pixel color is determined by a layer of tiny capsules filled with charged white pigments in a black fluid. An activated transistor creates an electric field that causes the pigments to move up or down in the capsules. When they drift to the top, the pixel appears white; when they sink to the bottom, it looks black.

Obviously, the pixels on such a sheet will have to become much smaller to accommodate entire pages of text. But the authors of the article are confident that the techniques they used to create the electric circuits will also work on a smaller scale. Imagine rolling an encyclopedia under your arm.