Self-healing circuits fix themselves after damage

Posted by Kate Taylor

University of Illinois engineers have developed a way of automatically restoring electrical conductivity to a cracked circuit in less time than it takes to blink.

With chip density increasing all the time, reliabilty is becoming more of an issue - there's simply more to go wrong. But the new material means that when a circuit cracks or fails, the chip can simply fix itself.

"In general there's not much avenue for manual repair," says materials science and engineering professor Nancy Sotto.

"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 team dispersed tiny microcapsules, just 10 microns in diameter, on top of a gold line functioning as a circuit. As a crack propagates, the microcapsules break open and release the liquid metal contained inside. The liquid metal fills in the gap in the circuit, restoring electrical flow.

After a failure, the current is interrupted for just a few microseconds, as the liquid metal immediately fills the crack. In tests, 90 percent of samples healed to 99 percent of their original conductivity.

"In an aircraft, especially a defense-based aircraft, there are miles and miles of conductive wire," says Sottos. "You don't often know where the break occurs. The autonomous part is nice – it knows where it broke, even if we don't."

Next, the researchers plan to check out whether their microcapsule-based self-healing system could be applied to batteries, improving their safety and longevity.