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Researchers Create Ultrastretchable Wires Using Liquid Metal 94

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."
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Researchers Create Ultrastretchable Wires Using Liquid Metal

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  • by fotoguzzi ( 230256 ) on Wednesday December 19, 2012 @10:06PM (#42343873)
    Just asking.
    • Re: (Score:2, Informative)

      by Anonymous Coward

      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.

    • by Anonymous Coward on Wednesday December 19, 2012 @10:54PM (#42344197)
      metallic gallium is not considered toxic
      Wikipedia on Gallium []
      Pure indium in metal form is considered nontoxic by most sources.
      Wikipedia on Indium []
    • by mirix ( 1649853 ) on Thursday December 20, 2012 @12:53AM (#42344839)

      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?)

      • by Skapare ( 16644 )

        I believe that coating is gallium oxide.

      • by tofarr ( 2467788 )
        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
  • by Metabolife ( 961249 ) on Wednesday December 19, 2012 @10:08PM (#42343881)
    Here comes the upgrade.
  • by The Grim Reefer ( 1162755 ) on Wednesday December 19, 2012 @10:08PM (#42343883)
    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.

    • by Jetra ( 2622687 )
      It seems we skipped the sentient AI and killer robots.
      • It seems we skipped the sentient AI and killer robots.

        Like that's a bad thing?

      • 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.

        • You mean like the robotic weapon that killed nine people and wounded 14 in October 2007? That was only news because it killed the wrong people. Bad Robot! Bad Robot! Unlike the Obama administration that targets rescuers at sites of drone missile strikes and mourners at the funerals of its victims. US military parlance for this double tapping. Bad President! Bad Policy! But not news because it's killing the right people, the innocent that live with the guilty.

    • by icebike ( 68054 ) on Wednesday December 19, 2012 @10:47PM (#42344159)

      so shouldn't this alter the conductivity of the 'wire'? []

      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.

      • by Guppy ( 12314 )

        Of course it also allows for some new circuit elements.

        Could be an interesting way to improve some variable/tunable elements that currently suffer from issues with contact wear or reliability issues. I'll bet designs even exist already, but have since become environmentally impractical due to being based on mercury.

      • That does not address the fact that the summary states that conductivity does not change as the wire is stretched.
        • by icebike ( 68054 )

          That does not address the fact that the summary states that conductivity does not change as the wire is stretched.

          The summary states no such thing.
          It states that conductivity reduction changes are offset by other changes that reduce resistance.
          However that offset is limited to a very small range of current and voltage. Mostly it works for voltage and amperage that would be
          found in signaling, not power transmission.

          One can not negate the basic laws of electrical transmission that huge amperage can not be carried on tiny wires.

    • unless the stretching of the wire alters the cross sectional conductivity

    • 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.
      • by hankwang ( 413283 ) on Thursday December 20, 2012 @03:01AM (#42345343) Homepage

        "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.

    • by Anonymous Coward

      Yes, and the resulting change in resistance in this kind of liquid-metal wire has been used for years in the medical field for 3 decades:

    • It's all in the game, yo.
  • by SwampChicken ( 1383905 ) on Wednesday December 19, 2012 @10:38PM (#42344093) a manufacturer near you. Spaghetti wiring to complement their existing spaghetti code.
    • well, vaccuum tubes *are* making a come-back. at least in terms of snootyphile audio systems.

      • by mcgrew ( 92797 ) *

        Vaccuum tubes never went away for guitarists, because overdriven transistors distort differently than overdriven tubes. Many guitar players will have a small tube amp with a microphone in front of it feeding a solid state amp -- the tube amp is for distortion, the solod state amp for amplification.

        If you look at it on an oscilloscope, when driven to distortion levels ("clipping") the transistors will produce square waves that are actually square, while the tube amp's waves are rounded at the corners and fla

  • What is the practical application of being able to freely apply even more jack/plug torsion exactly?

  • A local contractor severed a wire today, killing 5 from heavy metal poisoning.
  • ...are finally finding something besides how to hack into some software.

  • by Anonymous Coward on Wednesday December 19, 2012 @11:07PM (#42344255)

    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?

  • Now when i bill a customer for "topping off their network fluid" it can actually be true?
    • I know it will be hard, but we'll just have to make sure we don't leave excess amounts of molten gallium on our aluminum based products for prolonged periods of time.

  • So, a network made from this type of wire really would be a series of tubes?
  • Hey, I just made stretchable ice!

  • by SuricouRaven ( 1897204 ) on Thursday December 20, 2012 @03:27AM (#42345459)

    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.

    • Metals that make springs make poor conductors. There is also the fact that springs have a stress limit. Pull to hard and they stay straight. For a spring to elongate it takes a large diameter spring relative to the diameter of the wire. The article states 8 times. That means the coil must be at least 2.5 times the diameter of the wire. Factor in double that so that the wire does will return to a coil makes it 5 times. The 1/8" wire would be a coil over 1/2" in diameter. Not so great for portable headphones.

  • Like, for example, knives...and stabbing weapons?
  • Sounds like a great idea for speaker cables. You can stretch the cable to whatever distance you need!

    Is it oxygen-free? I hate how oxygen ruins the timbre of my cables. ;-)

  • Finally we can get rid of all that copper wiring and replace it with tubes of liquid metal, as it should have been!

The wages of sin are high but you get your money's worth.