Would repeated stretching and relaxing not induce an electro-magnetic field which can be tapped for energy? That way, novelty t-shirts with flashing led's or that respond to or play music wouldn't need batteries, or at least require smaller batteries that would last a lot longer.

one challenge needs to be addressed before the wires can be considered for popular products: how to minimize leakage of the metal if the wires are severed.

Perhaps they could compound the liquid metal alloy directly with the elastomer, using a High let-down-ratio (LDR), and then inject this resulting composite into the elastomer extrusion (tube)? The core will then be a "gel", which will not leak,.. while maintaining the physical properties of the tube.

"one challenge needs to be addressed before the wires can be considered for popular products: how to minimize leakage of the metal if the wires are severed"

maybe mix the liquid metal with something so it solidifies in contact with air

I'm guessing this could be useful in robotics by allowing wiring that flexes better.

Electronic biomimickry is a field where "synthetic muscles" and other robot structures are made to pattern animal behavior at the nano-scale to produce more flexibility. Having flexible and even extendable wiring could potentially solve lots of problems.

I could conceive of something like this for the power supply cables for actual skeletal muscles in a robot or a prosthetic device, although you'd want to coat it in a way that would be safe for the body in the case of implants.

Great concept but mass producing products, like headphones, with rare earth metals may not be the best application. Robotics or specialized medical products may be the wiser route.

Since the resistance of the wire is dependent on the cross-section area and lenght, which changes when you pull on it, you can use it as an excellent sensor for stretching and strain over much greater distances than other strain gauges.

That's extremely useful, because you no longer need sliding contact potentiometers or elaborate digital encoders to detect e.g. the angle of a limb. You could incorporate the wire directly into an analog PID feedback loop and do away with a lot of processing.

Nope, it wouldn't. Why the deform of metal should lead into electromagnetic field? Not quite accidentally, you were upvoted for it with three people already.

(wish I could flag you for bad English)

Why, indeed. First: this is not the place to instruct you in the basics of electromagnetic induction - that knowledge is assumed for anyone responding to the article, and is, incidentally, quite obviously not there in your case. Second: people "upvoted" me because I have given them ideas, and you can assume that they do actually know what I am talking about. But, why "quite accidentally"?

Because the PO is increasingly flooded with naive kids, who A) don't understand physics and B) who expect huge exploitation of every silly result of basic research regardless its actual price. Just such silly publics enables the lazy incompetent scientists to survive.

Because the PO is increasingly flooded with naive kids, who A) don't understand physics and B) who expect huge exploitation of every silly result of basic research regardless its actual price. Just such silly publics enables the lazy incompetent scientists to survive.

Does that mean that the aether flat water wave model is no longer applicable to non moving electrons?

But in this case he's correct. Simply waving a piece of metal about (or stretchig/compressing it or tying it in knots or whatever) doesn't induce anything....UNLESS you do it relative to a magnetic field which has at least some component at right angles to the (loop of) wire.

But if you're now thinking of using the Earth's magnetic field then that is so weak that the induced current is utterly negligible.

The rare metals are just being used in the lab because of how easy they are to work with. I am sure they will find liquid alloys for abundant metals in short order.

Yep, sodium/potassium alloy...

Simply waving a piece of metal about doesn't induce anything

But if you're now thinking of using the Earth's magnetic field...

Speaking of which, I understood that the earth's magnetic field is due to the motion of molten metal in the outer core. At sufficient speeds and configurations, bits of moving metals can and do become self-excited dynamos that amplify any existing magnetic field, however small.