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Researchers Create Ultrastretchable Wires Using Liquid Metal
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."
Here comes the upgrade.
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.
...to a manufacturer near you. Spaghetti wiring to complement their existing spaghetti code.
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.
Sig Battery depleted. Reverting to safe mode.
Good thing Indium and Gallium aren't toxic or heavy metals then eh
metallic gallium is not considered toxic
Wikipedia on Gallium
Pure indium in metal form is considered nontoxic by most sources.
Wikipedia on Indium
Yeah, okay, someone mod me down :(
I tried to be funny, can't fault a man for trying.
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?
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?)
Sent from my PDP-11
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.
"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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