Flexible Electronics One Step Closer With New Circuits

December 15, 2005

New silicon circuitry can bend and stretch like rubber, without losing its ability to function.

Flexible circuits could give electronic devices—including digital cameras, iPods, and TVs—a host of new and improved capabilities.

And manufacturers might someday be able to add electronics to the surfaces of devices that currently lack them (think heart monitors built into surgical gloves or artificial limbs with "skin" that can sense touch).

"These concepts are technically feasible," said electrical engineer Sigurd Wagner of Princeton University, who was not part of the research team. "But none of them is yet practical."

University of Illinois materials scientist John A. Rogers masterminded the innovation. "Silicon is intrinsically a brittle material, and you're not going to get around that," he said. "But you can come up with tricks to avoid that problem."

Engineers can already make electronics that flex without snapping, such as the superthin microprocessors in smart cards.

Smart cards are small plastic cards that store and process data and records. The most common examples in the United States are credit cards that house their microprocessors under small, square, gold contact pads.

"Smart cards have very small integrated circuits," Princeton's Wagner said. Each circuit "is so thin that when you sit on your wallet [the microprocessor] doesn't break."

The field's ultimate goal, experts say, is to make circuits that can conform to a curved surface or that can change shape as they function.

Making Waves

"Bendability and stretchability are different mechanical characteristics," said Illinois's Rogers. For example, paper can bend but not stretch.

To create stretchable electronics, Rogers and his colleagues first made ribbons of silicon using a standard method.

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