Self-Healing Electronic Circuits Created
December 21, 2011 by UPI - United Press International, Inc.
CHAMPAIGN, Ill., Dec. 20 (UPI) — U.S. researchers say they’ve develop self-healing electronic circuits that could extend the life of electronic devices and batteries.
As electronic devices evolve and circuits get ever smaller, manufacturers are packing as much density onto a chip as possible, but that raises reliability problems, such as failure stemming from fluctuating temperature cycles as the device operates, researchers said.
“In general there’s not much avenue for manual repair,” University of Illinois materials science professor Nancy Sottos said. “Sometimes you just can’t get to the inside. In a multilayer integrated circuit, there’s no opening it up. Normally you just replace the whole chip. It’s true for a battery too. You can’t pull a battery apart and try to find the source of the failure.”
The Illinois researchers had previously developed a system for self-healing polymer materials and adapted their technique for conductive systems.
They disperse tiny microcapsules on top of a gold line functioning as a circuit, and as a crack develops, the microcapsules break open and release the liquid metal contained inside.
The liquid metal fills in the gap in the circuit, restoring electrical flow.
A failure only interrupts current for mere microseconds, researchers said, before the liquid metal immediately fills the crack.
Nearly 90 percent of their samples healed to 99 percent of original conductivity even with a small amount of microcapsules, they said.
The self-healing system has the advantages of being localized and autonomous, Sottos said.
“In an aircraft, especially a defense-based aircraft, there are miles and miles of conductive wire,” she said. “You don’t often know where the break occurs. The autonomous part is nice — it knows where it broke, even if we don’t.”