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Researchers Create Ultrastretchable Wires Using Liquid Metal

Posted by samzenpus on from the keep-it-stretching dept.

hypnosec writes "By using liquid metal researchers have created wires that can stretch up to eight times their original length while retaining their conduction properties. Scientists over at North Carolina State University made the stretchable wires by filling in a tube made out of an extremely elastic polymer with gallium and an indium liquid metal alloy."

19 of 94 comments (clear)

  1. Are they worried about leaks? by fotoguzzi · · Score: 2

    Just asking.

    --
    Their they're doing there hair.
    1. Re:Are they worried about leaks? by Anonymous Coward · · Score: 2, Informative

      Researchers [...] have stressed that work needs to be done to address one critical aspect of the wire though – leakage of liquid metal in case the wire is severed.

    2. Re:Are they worried about leaks? by Anonymous Coward · · Score: 5, Informative

      metallic gallium is not considered toxic
      Wikipedia on Gallium
      Pure indium in metal form is considered nontoxic by most sources.
      Wikipedia on Indium

    3. Re:Are they worried about leaks? by Anonymous Coward · · Score: 2, Informative

      i would imagine airlines would frown upon gallium anywhere near their aircraft through.

    4. Re:Are they worried about leaks? by mirix · · Score: 4, Informative

      When they ditched mercury thermometers due to toxicity / envrionmental hazards, the replacement is galinstan - gallium, indium, and tin. So it is considerably less toxic.

      Unfortunately it wets to glass, unlike mercury which beads up, and is more expensive.
      The way around that is to coat the glass with something - I don't recall what now, but I think it was some gallium compound.

      On the more expensive front - I'd think both gallium and indium are a couple orders of magnitude more expensive than copper, so don't count on that going away any time soon. (Not to mention copper itself is 'expensive' [~$5/kg, it varies], and manufacturers are cheaping out on it. 12 AWG booster cables?! What kind of sick joke is that?)

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    5. Re:Are they worried about leaks? by fufufang · · Score: 3, Informative

      metallic gallium is not considered toxic

      Wikipedia on Gallium

      Pure indium in metal form is considered nontoxic by most sources.

      Wikipedia on Indium

      Yes, but if it ever leaks out, Gallium might cause structural failure of anything that's made of aluminium. And certainly I don't want to have conductive liquid in my electronic devices, when the cable breaks.

    6. Re:Are they worried about leaks? by tofarr · · Score: 2

      Also copper thieves would have a field day - no need to haul anything away - just cut the cable near the bottom and watch the metal flow into a bucket

  2. Arnold won't be happy by Metabolife · · Score: 3, Funny

    Here comes the upgrade.

  3. Add campaign... by The+Grim+Reefer · · Score: 3, Funny
    I can see it now.

    John Connor: These wires are made of what?

    The Terminator: A mimetic poly-alloy.

    John Connor: What the Hell does that mean?

    The Terminator: Liquid metal.

    1. Re:Add campaign... by davester666 · · Score: 3

      No we didn't.

      We just launched SkyNet into orbit. We have teams working on autonomous robots with the ability to identify and kill human targets. We have other teams working on making better CPU's, image processing, faster wireless networking, better materials for constructing robots, as well as ongoing creation and testing of new and improved weapons on humans.

      Things are progressing on schedule. We appreciate your cooperation.

      --
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  4. Coming soon... by SwampChicken · · Score: 5, Funny

    ...to a manufacturer near you. Spaghetti wiring to complement their existing spaghetti code.

  5. Today's news at 5 by skitchen8 · · Score: 2, Funny

    A local contractor severed a wire today, killing 5 from heavy metal poisoning.

    1. Re:Today's news at 5 by viperidaenz · · Score: 3, Informative

      Good thing Indium and Gallium aren't toxic or heavy metals then eh

    2. Re: Today's news at 5 by skitchen8 · · Score: 3, Funny

      Yeah, okay, someone mod me down :( I tried to be funny, can't fault a man for trying.

  6. Re:The cross section changes by icebike · · Score: 3, Interesting

    so shouldn't this alter the conductivity of the 'wire'? http://en.wikipedia.org/wiki/Electrical_resistance_and_conductance#Relation_to_resistivity_and_conductivity

    One would think so.

    But you could design for that, simply by using the smallest diameter as your critical dimension when selecting wire size.

    Of course it also allows for some new circuit elements, those that can measure stretch via voltage drop, which might be very useful in robotics or prosthetics.
    In short it might not be as much of a detriment as it is an advantage.

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  7. In a good way, balancing diameter by raymorris · · Score: 2, Informative

    From TFA, the changing cross srction reduces resistance as it stretches. At the same time, stretching increases resistance due to reduced diameter. The two effects tend to cancel one either, so they could be designed for no change when stretched, if it mattered to the application. In 99% of cases, it doesn't matter. You simply want "low resistance" and don't care if it's 0.012 ohm or 0.015 ohm.

    1. Re:In a good way, balancing diameter by hankwang · · Score: 3, Informative

      "From TFA, the changing cross srction reduces resistance as it stretches. ... they could be designed for no change when stretched"

      Well, that's not quite what TFA writes: "As expected, electrical measurements show that the fibers increase resistance as the fiber elongates and the cross sectional area narrows. Fibers with large diameters (~600 [micrometers]) change from a triangular to a more circular cross-section during stretching, which has the appeal of lowering the resistance below that predicted by theory."

      The abstract doesn't mention how the circular/triangular transition would affect the resistance - with conservation of volume it shouldn't matter. But I don't read here in any way that this effect would be able to cancel the resistance increase due to stretching.

      Note that in first approximation, resistance would scale as L^2 for a wire with length L (both diameter decrease and length increase affect the resistance). With stretching up to a factor 10, i.e. 100x increase in resistance, a small effect due to the shape of the cross section would be negligible.

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  8. Isn't this 30 year old technology? by Anonymous Coward · · Score: 4, Interesting

    This sounds exactly like an indium-gallium strain gauge, which in turn is an evolution of the mercury-in-rubber strain gauge used for at least 30 years in medical measurements. These are rubber tubes filled with liquid metal, just like the "wires" described in this article. Their resistance increases as they are stretched, and they've been used for everything from monitoring respiration (wrapped around the chest) to monitoring blood pressure. A quick search on "Strain Gauge Plethysmography" will produce some relavent pages.

    Thus this seems like a just a new use for an old technology. Am I missing something?

  9. That's one way to do it. by SuricouRaven · · Score: 2

    Wouldn't it be simpler to just take a spring and put an insulating plastic jacket around it? Higher resistance, but no leak hazard, could be cut to length as required, and easily made on existing production lines.