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Hardware Science

Liquid Metal Capsules Used To Make Self-Healing Electronics 135

MrSeb writes "A crack team of engineers at the University of Illinois has developed an electronic circuit that autonomously self-heals when its metal wires are broken. This self-healing system restores conductivity within 'mere microseconds,' which is apparently fast enough that operation can continue without interruption. The self-healing mechanism is delightfully simple: The engineers place a bunch of 10-micron (0.01mm) microcapsules along the length of a circuit. The microcapsules are full of liquid metal, a gallium-indium alloy, and if the circuit underneath cracks, so do the microcapsules (90% of the time, anyway — the tech isn't perfect yet!). The liquid metal oozes into the circuit board, restoring up to 99% conductivity, and everything continues as normal. This even works with multi-layer printed circuit boards (PCBs), such the motherboard in your computer, too. There's no word on whether this same technology could one day be used by Terminators to self-heal shotgun blasts to the face, but it certainly sounds quite similar. The immediate use-cases are in extreme environments (aerospace), and batteries (which can't be taken apart to fix), but long term we might one day buy motherboards with these self-healing microcapsules built in."
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Liquid Metal Capsules Used To Make Self-Healing Electronics

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  • Not such a good idea (Score:5, Interesting)

    by ka9dgx ( 72702 ) on Wednesday December 21, 2011 @02:40PM (#38452018) Homepage Journal

    I know it would be an alloy... but Gallium isn't such a great thing to be shipping around in airplanes, this youtube video of gallium eating an aluminum can [] for an idea why.

  • Doesn't add up (Score:5, Interesting)

    by Asic Eng ( 193332 ) on Wednesday December 21, 2011 @03:31PM (#38452624)

    The article states this technology is intended to automatically repair integrated circuits via "microcapsules, as small as 10 microns in diameter". Being charitable and going with 90 nm geometries (which we still used in our company last year - we are a bit slow) that's too large by a factor of 100. Interesting for PCBs, but not for integrated circuits.

    The article also states that the technology would fix things "so fast that the user never knew there was a problem" and then explains that "a failure interrupts current for mere microseconds".

    The summary corrupts that somewhat into the claim that "operation can continue without interruption". It's far too slow for that. Let's assume a rather slow 33 MHz bus - that gives us a clock period of 30 ns - so we'd miss at least 33 clock cycles in this scenario. This interruption might not be noticed by the user, if an error correcting protocol is used on the bus and the system retransmits. Otherwise you would get wrong data, and you have to assume that will be noticed sooner or later.

    Interesting technology on PCBs or communication wires, I could see it being used in safety-critical applications. On integrated circuits it doesn't seem feasible. Basically you make the transistors and wires on ICs already as small as you can. To repair the wires on the IC you now need to insert capsules into the wires to do the automatic repair - so they would be way smaller than the wires. If you could manufacture these structures you'd make the wires smaller though and then you'd lose your ability to insert the microcapsules ... there is no way to win that race.

  • by jank1887 ( 815982 ) on Wednesday December 21, 2011 @03:43PM (#38452792)

    traces don't break. they suffer from electromigration []. I.e., where the constant collision of electrons with the metal lattice eventually creates voids in the metal. Becomes more of a problem with higher power processors and narrower conductors. some metals are more susceptible as well. (aluminum more than copper, i think).

    And similarly, they would get hot (due to the high current density in the near break) before they break, and this heat could trigger the liquid metal release. There are applications for high-reliability electronics. I think the automotive sector is the one that most easily comes to mind for the consumer market. Long use equiment, like medical equipment maybe too.

    Also, don't forget, the equipment you have is designed to operate as long as necessary without the types of failures this would solve. Given this tool, could they be designed differently? More efficiently? Smaller? Maybe.

  • Re:Crack Team? (Score:4, Interesting)

    by elewton ( 1743958 ) on Wednesday December 21, 2011 @03:57PM (#38452992)

    I don't know about *MOST* users lives. Most the people I know who use cocaine seem to do so infrequently, and as part of a balanced diet. That seems to be representative of coke users in general; problem users seem to represent 5%-15% of the population, similar to a lot of drugs, though the problematic effects are fairly severe, as is dependence.

    Crack cocaine is also a very different drug from base cocaine.

    I don't use either, and don't want to.

"There is nothing new under the sun, but there are lots of old things we don't know yet." -Ambrose Bierce