If just a single circuit in a complex integrated electronics chip fails, an entire device can be rendered useless. But what if a chip had the ability to heal itself and restore the device to full capacity? A team of engineers at the University of Illinois have come up with a way to make that possible.
The innovation — the latest in the quest for self-healing electronics — centers on the use of tiny microcapsules of liquid metal called gallium-indium, which has a high conductivity and low-temperature melting point. When a circuit breaks and electrical conductivity is disrupted, the microcapsules — each as small as 10 microns in diameter — release their liquid metal payload. The metal fills in the gap in the circuit within microseconds, restoring up to 99 percent of the original conductivity.
The team's paper, Autonomic Restoration of Electrical Conductivity, was published online Dec. 20 in the journal Advanced Materials.
Microcapsules like this have previously been used with self-healing polymers developed by the same team.
"What’s really cool about this paper," said co-author Scott White in a prepared statement, "is it's the first example of taking the microcapsule-based healing approach and applying it to a new function. Everything prior to this has been on structural repair. This is on conductivity restoration. It shows the concept translates to other things as well."
Another author, Nancy Sottos, said this technique will make many currently common electronics repairs unnecessary. "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 says the self-healing properties could be applied to consumer electronics such as computers or mobile phones — thereby reducing e-waste — or to even more complex systems, such as defense systems or space vehicles, where repair opportunities are extremely limited. Since the system would repair itself, it would also make timely diagnostics a thing of the past.
"In an aircraft, especially a defense-based aircraft, there are miles and miles of conductive wire," Sottos 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."
In tests, the team monitored circuits that had been repaired by the microcapsules for four months and found no further loss of conductivity.