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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."
Just asking.
Their they're doing there hair.
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.
so shouldn't this alter the conductivity of the 'wire'? http://en.wikipedia.org/wiki/Electrical_resistance_and_conductance#Relation_to_resistivity_and_conductivity
...to a manufacturer near you. Spaghetti wiring to complement their existing spaghetti code.
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.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
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.
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?
http://www.youtube.com/watch?v=JHHI2Lk79cY
So, a network made from this type of wire really would be a series of tubes?
It's unlikely you could pinch it thin enough to do what you're describing. This is electron flow, not simple liquid pressure that you can cut off by pinching a hose.
File under 'M' for 'Manic ranting'
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.
The tube would likely kink quite easily, squeezing out the liquid from the middle - thus stopping the electron flow - or reducing the diameter so much as to greatly alter the resistance of the wire. Something like this image: http://hostedmedia.reimanpub.com/TFH/Step-By-Step/FH10SEP_BUYHOS_01.jpg.
Moved to http://soylentnews.org/. You are invited to join us too!
why, so you can fuck up your headphone jack even more?
Hey, I just made stretchable ice!
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
No, it would not stop electron flow. It would reduce the cross sectional area, and could thus marginally increase the resistance in the wire, but it would not stop electrons like it would a flow of liquid. Electrons are *REALLY* tiny... far tinier than what it would take to simply make a seal tight against even single molecules of liquid.
File under 'M' for 'Manic ranting'
So you can say "Get off the cord ; I cant't hear the music"?
If the tube is crushed flat there would be no liquid metal there for the electrons to flow through. Sorry but electrons flow from atom to atom. If the pinch is wide enough the electrons will not be able to jump the gap. The electron flow needs a continuous conductor. if the pinch creates a gap of 1/4 of a mm in the liquid the flow of electrons will be stopped.
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.
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. ;-)
As you approach that pinching point the increased resistance creates heat, you'd likely melt the wire if you pinched it down and it didn't stop the electron flow. Imagine the melted wire ends leaking electrically conductive puddles that then have hundreds of tiny contact points, not to mention ground. Could be very dangerous -- The wire busts and electrocutes people. Also, too many electrons flowing in too small a wire (or even between two small a path between conductive puddles) are how electrical fires start. The whole electrical code falls under the NFPA for this reason (National Fire Protection Agency).
First of all, I don't think you appreciate how tiny that gap would have to be.
Second of all, to even started to approach that requisite size would require *FAR* more work than pinching it with your fingers, or even folding it in half like a tube. You'd need many times more force, and more than likely that amount of pinching force would end up cutting the wire completely long before it would simply halt the electron flow with the insulation intact (unless the insulation itself were as ductile as, say.... gold, which can be pressed to thicknesses on the order of only a handful of atoms across). And the scale of how tiny a gap we're talking about here is small enough that the electrostatic repulsion between electrons is going to be a dominant force, and is going to actively push things away, keeping an almost infinitesimally small gap open, and I'd dare say would require many tons per square inch of pressure to achieve.
Long before you get to this point, the reduced cross section of wire would increase the resistance in the wire enough to cause any ordinary insulation around the wire to start to melt. If the issue of preventing leakage of the fluid can be addressed (which, admittedly, it has not been so far), then that level of abuse (because in practice, it would probably take deliberate abuse to create the scenario where that much force is acting on it, and not something that happens coincidentally) would be about as serious as if the wire had simply been cut. And in general, that kind of pinching force acting on the wire would tend to break it anyways, unless it is made out of some extraordinary material.
File under 'M' for 'Manic ranting'
Finally we can get rid of all that copper wiring and replace it with tubes of liquid metal, as it should have been!
The point you miss is that electrons do not flow through air very well; that would be called a spark. The sides of the tube do not have to be close enough to cut off the flow of electrons; it just has to be small enough to separate the liquid conductor. If there is a gap in the conductor there will be no electron flow.
As for melting the insulation, that would require a lot of power to push the electrons against the resistance to create enough heat. Most headphones do not have enough power to do that as electron flow would just stop. Another point is that if the tube is crimped quickly it will act like a switch and there will not be enough time for heat to build up.
As for the scenario; did you look at the picture in a previous post? It does not take a lot of force. All it requires is a loop and pulling the ends a bit to create a pinch in the tube much like is done to crimp off a water hose. There is a point at which the sides are close enough to stop water flow. That same kind of crimp is enough to separate the liquid conductor. Remember that the tube elongates 8 time that means it is pretty elastic. That means that it would crush pretty easily. I bet I could crush the tubing with my fingers enough to separate the conducting fluid.
Melting would only occur if there was enough power in the wire to create the heat. Headphone work at low voltage and low amperage. The most powerful headphones I found were 200mW. That is far from enough power to melt plastic. Sure if it was being used for household current it might occur but that is not what this device is designed for.
Which I am asserting that no normal amount of pressure could hope to achieve without actually breaking the wire in the first place.
Yes, I looked at the picture of the hose... but we're not talking about stopping liquid flow, we're talking about stopping electron flow.
Enough to stop the liquid from flowing through the gap, yes... not enough to stop it from conducting electricity.... at least not without creating sufficient pinching force that you actually cut the wire.
File under 'M' for 'Manic ranting'
Which I am asserting that no normal amount of pressure could hope to achieve without actually breaking the wire in the first place.
A plastic tube that is malleable enough to stretch 8 times its length is malleable enough to be crushed flat without "breaking". Take some rubber tubing, fill it with water and crimp it like the picture. That is exactly what this device is. It is not a wire with a solid core; the core is liquid and will move out of the way of a crimp.
Enough to stop the liquid from flowing through the gap, yes
This shows how little you understand the concept. The liquid does not flow at all. The electrons cascade through the liquid. Where there is no liquid, as in a pinch, there is no electron flow. If the sides of the tube are touching each other what atoms are exchanging electrons so the charge moves? It isn't the tubing as that is an insulator. Electrons do not flow. They jump from one atom to another. If two atoms of the liquid metal are not touching there will be no electron flow. With enough energy electrons can cross short gaps. That is called a spark and takes a lot of voltage to accomplish. That is far beyond the voltages in a headphone wire.
You don't account for the sutface tension. If you squeeze the tube thin enough, the liquid may gain energy by breaking up.
Think of water running out of a tap. The stream gets thinner and thinner as it falls and then breaks up into separate droplets.
Avantslash: low-bandwidth mobile slashdot.
Half right. Where there is no liquid there is no electron flow. However, your faulty assumption is assuming that there wouldn't be any of the conductor inside a pinched area.
There's a handful of reasons why this is so, not the least of which is the fact that this isn't like a hose where the liquid you displace by pinching can flow out of either end... it's a flexible container, but it's closed on either end... and it's also *FILLED* with liquid that doesn't compress, and not merely partially filled, leaving much compressible gas inside, so pinching it doesn't leave the liquid with anywhere to really flow to. The container is flexible, but all it can do is stretch to accommodate the change in the cross sectional area of the wire. The amount that the wire would have to stretch to be pinched to such thinness to make room for all of the displaced liquid would, again, tear apart the wire itself unless it were made out of an abnormally ductile substance (which rubber is not). In the end, any amount of nominal pressure pinching would not accomplish this. No matter what mechanism you used to pinch it, the effect would be exactly the same as if you took scissors to the wire, which also accomplishes its effect by simply pinching.
I can't really assert that you couldn't possibly pinch it this tightly at all, only that if you were to, the result would also be a severed wire, and that such high amounts of stress are not liable to happen in practice.
Bearing in mind also that nowhere in this article does it even imply that this kind of wire would be applicable to industrial situations where such forces would have a moderate chance of occurring. The power levels implied by the article are on the order of what you'd get in a set of headphone wires, and not what you'd be using to run power to appliances.
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There's a handful of reasons why this is so, not the least of which is the fact that this isn't like a hose where the liquid you displace by pinching can flow out of either end... it's a flexible container, but it's closed on either end.
Yes it is but it is also a flexible container that can change it cross section. If you press one part of the tube another part of the tube can balloon out and accommodate the liquid.
The amount that the wire would have to stretch to be pinched to such thinness to make room for all of the displaced liquid would, again, tear apart the wire itself unless it were made out of an abnormally ductile substance (which rubber is not).
The tube is very ductile. It can elongate 8 times it's original length. Say one has a 5" long wire and 1/2" is pinched flat. The rest of the wire would have to accommodate .5/59.9= 8% more liquid. That would mean that the rest of the wire would have to increase its diameter by 1.6%. That would not be difficult for a material that can elongate by 800%.
Industrial situations are not the problem. All it takes is a loop in the wire, a closed door or someone stepping on the tube. I think what may be causing the issue is that you are thinking of large tubes while I am thinking of tubes around 1/8" which would replace headphone wiring.
When it is free to do so, yes... if you are pinching it, then it *ISN'T* free to elongate along the region that you are pinching it. The result is a shearing force that will almost certainly sever it just as certainly as scissors would.
File under 'M' for 'Manic ranting'
if you are pinching it, then it *ISN'T* free to elongate along the region that you are pinching it.
So what? My point is that if it can elongate it can also bulge and the liquid displaces from the pinch will be accommodation by deforming the rest of the tube.
The result is a shearing force that will almost certainly sever it just as certainly as scissors would.
Yes scissors would be a shearing force but what I am talking about is a crushing force. Take the tube, put it into a C clamp and tighten. The tube will collapse long before it cuts. That is a crushing force. You really need to learn some physics. A shearing force is high pressure over a very narrow area. A crushing force is also high pressure but over a much larger area. Shearing forces cut while crushing forces generally cause deformation but do not cut. I have some silicone tubing that is about 1/8" outside diameter. It is very stretchy and probably would accommodate the liquid conductor quite well. I can elongate it quite far and I can crush it closed with my fingers without cutting it..
But when it elongates, the cross sectional area also reduces... The inside volume remains constant. It doesn't magically create more volume for the liquid core to seep into and liquid dont compress very easily like gasses do. The net result is that there won't be any place for the liquid you are trying to displace by pinching it to go to
File under 'M' for 'Manic ranting'
The cross section reduces because the fluid has a place to go in the longer tube. If one pushed the fluid up to one end of the tube the cross section would get bigger and the wall thickness thinner.
Take a long thin balloon and fill it with water. Hold both ends and pull. It will elongate. Grab the middle and squeeze. The ends will bulge which will accommodate the liquid. There is no magic about it. It is simple elastic physics. Anything that can elongate can also bulge.
A balloon's elasticity is such that it's volume can be increased considerably past a point of normal inflation. As you stretch the balloon, the thickness of the skin changes, and it doesn't necessarily have to get skinnier in another dimension like this wire does. With this wire, as you stretch it, the cross sectional area decreases, so the internal volume stays constant. The volume of liquid that you would be trying to squeeze out of the space where you are pinching would have nowhere to go... and the section itself that you are reducing the cross section of won't expand to accommodate the liquid because you are pinching it and preventing that section from lengthening.
File under 'M' for 'Manic ranting'
It is simple. the section one is not pinching will expand to accommodate the liquid. The liquid from the area being pinched goes into the area not being pinched which bulges to accommodate the liquid. It is called elasticity. Whether it is lengthened or not is irrelevant. The fact is that if the tube can lengthen means it can also bulge. You can't constrain an elastic material to only lengthen in one direction. If the tube can lengthen it can also increase circumference. The tube can increase circumference to accommodate the liquid displaced by the pinch. I am not talking about pinching the whole tube flat as that is impossible. As I stated, if one pinched 5% of the length of the tube flat there is plenty of elasticity to accommodate the shift in fluid.
No... not at all. It *CAN*, but that is not the same thing as meaning that it would. And in fact, for something like wire insulation, it probably *wouldn't*, because taking a vertically running wire, for instance, the ability it to bulge would cause it to bulge out at the bottom end of the wire, leaving relatively little conductive liquid near the top, and creating an inconsistent conductivity across the wire.
File under 'M' for 'Manic ranting'
If you are such a materials expert how can one allow the tube to elongate but constrain it from bulging? You can't. The scenario you propose is only a problem it it bulged easily like a latex balloon. It is not a problem if it takes a reasonable amount of pressure to bulge. The couple of ounces of liquid metal in a tube will create a few psi in the bottom end of a vertical wire. Now say you put 30PSI on a small section of the wire. That small section will flatten and the rest will bulge slightly. Look at the math I showed you in previous posts. To accommodate a 1/2" pinch in a 5' wire it would have to bulge by less than 2%. Not a big deal in a tube that can elongate 800%.
Have you ever played with elastic tubes? I doubt it. So how are you such an expert in their properties? I have in my possession some silicone tubing that would work quite well for this application. It has a thick wall to resist bulging due to the weight of the liquid, will elongate quite well and will also bulge without breaking if enough pressure is applied. Have you looked at a real piece of tubing or are you just guessing? The advancement is not the tubing it is the alloy in the conductor.
So far you have been incorrect in how electron charge flows (the electron themselves do not), You have no idea how elastics work (if the can elongate along a tube they can also elongate around the circumference causing bulges). You have no idea how to tune elastics (the tube can be stiff enough to support the weight of the liquid but still deform under enough pressure). You have shown that you can not differentiate shearing force and crushing force. You have no concept of how small a change in the tube would be required to accommodate a crimp. So far you have shown no understanding of electricity, mathematics, physics or materials science and no desire to learn therefore this will be my last post. I am tired of talking to a brick wall.
First of all, try the following experiment: Since you evidently have silicone tubes to work with, take an 18" long or so silicone tube, and completely fill it with water completely seal both sides, and making sure that there is no air inside the tube. Once you've done this, you will note that the pressure required to flatten it with liquid inside is *DRASTICALLY* larger than it is when it is just air... or even if the liquid inside has someplace else to go, such as what you get with a hose that is experiencing only modest amounts of pressure from one side, such as what you get with a water hose, and not something that you're liable to experience in a non-industrial setting.
But to actually cut off electricity, assuming a conductive liquid core, you are going to have to squeeze it so tightly that not even a single molecule of thickness exists inside the body of the tube across the gap you are squeezing. This is quite a bit thinner than what you need to stop water pressure for a garden hose, and is a *LOT* harder than you might think... since even solid objects that appear to be touching on a macroscopic scale are not *REALLY* physically in contact with eachother at an atomic scale - rather, the electrostatic repulsion between their atoms' electrons will push to keep the substances separated by an distance which is *EASILY* wide enough for electrons which are being drawn by an opposite charge in a conductive material to pass But of course. in general, the level of force required to even get the material to this stage would probably cut the material.
But assuming that it could survive those forces, then the resistance of the wire would rise so sharply as that tiny a cross section was approached, that the heat would melt the insulation, and with a liquid core, it would render the wire just as useless as if it had been physically cut.
Finally, there's also the fact that at these kinds of scales, there's not a whole lot of difference between conductor and insulator, even the best insulators will not prevent electricity from flowing some small distance, and over the gap that you are trying to squeeze the liqud out of, even if you were to actually separate one side of the tube from the other, keeping the tube itself intact, across the gap itself between the two sides of the tube and where the tube is being squeezed, there would be many millions or even billions of isolated pools of the conductor that, themselves, would be close enough to eachother that electricity could effectively arc between them through the insulative material, while still being far enough apart that nominal amounts of macroscopic pressure, such as what you experience in a water hose, would not actually push through.
File under 'M' for 'Manic ranting'
Sorry but you are a moron.
I've attempted to describe to you what would happen at the very tiny scales that would be easily wide enough for electrons to pass, while still being far too tiny for the surface tension of the liquid to permit the formation of droplets that would allow macroscopic flow. Again, everyday experience with the macroscopic, such as what you'd get with a water hose and blocking water by crimping it just doesn't translate very well to scales as small as what you need to actually block electron flow.
However, if you're convinced that I'm a moron, then there's not much point in continuing this. But for the record, resorting to ad hominems doesn't exactly strengthen your position.
File under 'M' for 'Manic ranting'
Perhaps you might want to read a little on how electrical current flows. The crimp does not stop the flow of electrons it separates the conductor so that there is no conductive material for the charge to flow through. Electrons to not flow through air except at very high voltages. Outside of a conductor dielectric breakdown must occur for current to flow.. You keep concentrating on the width of the crimp but ignore the length. If I can create a gap in the conductor fluid 1/2 mm long no matter how thick the gap no electrical charge will flow. The potential needed to jump a mm of air is about 3kV. A 5V charge would not make it. It is even worse when there is not enough space for air to be so there is no possibility if ionization. You can not seem to get it through your head that electron flow is not separate from the atoms that they make up. Electrons are not tiny bits of matter that flow like water. They are charges that move from atom to atom in material that readily accepts and releases charges, conductors, and is stopped by materials that do not exchange charges well, insulators, What you continue to ignore is that if there is no conductor, at the voltages we are talking about, there is no charge flow.
It's this point that you're wrong about. You'll get an inkling of what I'm talking about if you try the experiment I described with a tube full of water and two sealed ends.
File under 'M' for 'Manic ranting'
How does electric charge flow when there is no conductor? If the tube is crimped so that the sides are touching there is no space for the liquid. You stated that yourself. Then you stated that there is enough room for "electrons to flow". If two attoms of the conductive fluid are more that 1/2mm apart the charge will not transfer between them. If a crimp is string enough to stop water at 50 psi it is strong enough to separate conductor under no pressure.
As for your experiment, I do not have the equipment to prove that there is no air in the tube so any results would be suspect at best. You still have not described how a n elastic material that can elongate 800% can't bulge by less than 2%.
you are going to have to squeeze it so tightly that not even a single molecule of thickness exists inside the body of the tube across the gap you are squeezing. This is quite a bit thinner than what you need to stop water pressure for a garden hose,
If the crimp is tight enough to stop molecules of water under pressure the why is it not tight enough to stop molecules of metal under very little pressure? Since it is stopping the liquid metal, the pinch would separate it.
There are two points you repeatedly get wrong;
1. Electrons do not flow outside of a conductor.
2. Elastic materials stretch in all directions.
Go to a high school or university and ask a physics instructor. They will explain it much better so that you can understand basic physics.
The former is caused by electrostatic repulsion between droplets of liquid, whose minimum size is determined by the surface tension properties of the liquid. But even these tiny droplets, which are on the order of only about a nanometer or two in size, are still about another order of magnitude larger than the molecules that liquid itself is made of.
File under 'M' for 'Manic ranting'