Photograph courtesy of Heiko Jacobs/University of Minnesota
Wouldn't it be nice if someday you could roll up your computer monitor, stuff it in your back pocket, and then unroll it so you could browse an online newspaper in a café or read e-mail off your palm-top computer? Heiko Jacobs, an electrical engineer now at the University of Minnesota, has been experimenting with flexible assemblies of LEDs that could possibly do just that. The invention grew out of his work in the laboratory of Harvard University chemist George Whitesides, a pioneer in using chemical interactions to self-assemble small structures. Recognizing that such interactions could eliminate many tedious steps in manufacturing common electronics, a team led by Jacobs developed a bendable LED screen that builds itself. The researchers fabricated a pattern of copper wires onto a half- inch- wide flexible plastic sheet, which they dipped in solder that sticks only to metal and then dunked into a water-filled vial. Next they threw in gold-coated LEDs, sealed and heated the vial, and gave it a good shake. The LEDs stuck only to the solder. Attaching a second pre-wired sheet, which functions as the top electrode, created a working display (above) in just a couple of minutes. The simplicity of the process means such displays could be both rugged and cheap, opening a wide range of applications. "You could have a screen wrapped around a pen that uses a built-in miniature cell phone to constantly change the display," Jacobs says.