A hard material is impregnated with microcapsules that burst when the material cracks, releasing a stored liquid that hardens on contact with the air, thus repairing the crack ... it's a system that we've recently seen used in a number of applications, including self-healing concrete and polymers. Now, a research team from the University of Illinois is applying it to electronics. They have already created a system that automatically restores conductivity to a cracked circuit in just a fraction of a second.
The scientists started with microcapsules as small as 10 microns in diameter, that were filled with a liquid metal. These were spread along the top of a line of gold, which was serving as an electrical circuit. When a crack formed in the gold, the capsules burst and instantly filled the crack with liquid metal, restoring the circuit within microseconds. Ninety percent of the samples were healed to 99 percent of their original conductivity, even when relatively small numbers of the microcapsules were used.
Such a system has several advantages over a traditional circuit, besides the obvious fact that it simply doesn't need to be fixed as often.
For one thing, it can often be very difficult to determine where a fault has occurred in an extensive electrical system, such as the miles of wiring inside an aircraft. With self-healing electronics, the break would be autonomously repaired where it occurred.
It would also be easier and less expensive to build electronics, as redundancies and sensory diagnostic systems wouldn't be nearly as important.
Finally, cracks could be healed on circuits located in areas that couldn't be accessed by hand. Ordinarily, when breaks occur in such places, the entire chip (or even the entire device) is just thrown away. By prolonging the lives of electrical systems, the self-healing technology would cut down on the amount of electronic waste entering the environment.
A paper recently published in the journal Advanced Materials details the University of Illinois research. Previously, scientists from that same institution were developing self-healing electronics that incorporated microcapsules filled with conductive nanotubes.