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Self-healing circuit at work  (Source: university if Illinois)
Tiny capsules of liquid metal keep things chugging along

There are numerous reasons why a circuit inside a gadget or electronic device might break. The result of a broken circuit inside a device is generally the device won't function properly or won't work at all. A team of researchers at the University of Illinois has discovered a cool and seemingly easy way to allow the damaged circuit to repair itself before the user knows there is a problem.
The researchers include Scott White, an aerospace engineering professor, Nancy Sottos, a materials science and engineering professor, and Jeffrey Moore, a chemistry professor. The team have taken a normal circuit and placed tiny capsules along its length that are about ten microns in size. Inside those little capsules is a liquid metal. When the circuit breaks, the capsules do too. The liquid metal then leaks out into the crack and the circuit is healed in microseconds. The repaired circuit has 99% of the conductivity of the original.
“It [the liquid metal polymer capsules] simplifies the system,” said chemistry professor Jeffrey Moore, a co-author of the paper. “Rather than having to build in redundancies or to build in a sensory diagnostics system, this material is designed to take care of the problem itself.” 
The idea of the self-healing capsules is for repairs in circuits that are hard to access for normal repairs. The researchers see potential for the self-healing circuits in aviation and spacecraft. The material may have used in automotive applications too. Hints have been dropped at self-healing properties similar to this for paint on vehicles in other research. This sort of self-repair would also be a great help for flexible electronic devices that are prone to have circuits break over time. 
"In general there’s not much avenue for manual repair,” 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."
In the past, the team developed a similar system for polymer materials repair and then adapted that system for conductive systems. “What’s really cool about this paper is it’s the first example of taking the microcapsule-based healing approach and applying it to a new function,” White said. “Everything prior to this has been on structural repair. This is on conductivity restoration. It shows the concept translates to other things as well.”


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Short Circuit?
By rickon66 on 12/22/2011 3:35:36 PM , Rating: 3
I would be concerned about the liquid flowing the wrong direction and hitting another circuit trace.

By drycrust3 on 12/22/2011 2:16:03 PM , Rating: 2
and the circuit is healed in microseconds.

A thought was that if the liquid metal was able to be controlled, e.g. by magnetic fields, then you may be able to create a microscopic "olde fashioned" relay, where, the two sides of the "break" in the electrical conductor were used as a set of electrical contacts, and when the liquid metal was shifted into the gap a "make" condition was achieved, and when the metal was moved out of the gap and then the electrical circuit "break" condition was achieved.
Maybe this could be used in very low voltage logic gates.

Cost and manufacturing?
By jahinoz on 12/22/2011 10:47:13 PM , Rating: 2
The application of this technology is appealing but it makes me wonder what the cost to manufacture it on a commerical scale would be. I can't imagine it would be cost effective (much like many other nanotechnologies at the moment) so it almost eliminates use in all industries except aerospace until a cheap way to manufacture can be found.

Download the original paper
By materialsdave on 12/27/2011 2:47:18 AM , Rating: 2
If you want to learn more, you can download the original Advanced Materials paper for free from .

Dave Flanagan, Advanced Materials

"If they're going to pirate somebody, we want it to be us rather than somebody else." -- Microsoft Business Group President Jeff Raikes
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