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."

Comments

Re:Are they worried about leaks?

[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.

Re:Today's news at 5

[viperidaenz]

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

Re:Are they worried about leaks?

[Anonymous Coward]

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

In a good way, balancing diameter

[raymorris]

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.

Re:In a good way, balancing diameter

[hankwang]

"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.

Re:Are they worried about leaks?

[Anonymous Coward]

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

Re:Are they worried about leaks?

[mirix]

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?)

Re:Are they worried about leaks?

[fufufang]

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.