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Science Technology

Fishing Line As Artificial "Muscle" 111

brindafella writes "Researchers have made what they describe as an 'almost embarrassing' discovery, that twisted nylon fishing line can form a 'powerful, large-stroke, high-stress artificial muscle' capable of lifting as much as 100 times more weight than human muscles. They twisted the fishing line, then heated it to 'set' the shape-memory. The scientists are from the Australian Research Centre of Excellence for Electromaterials Science at the University of Wollongong, and the University of Texas. The findings are published in Science magazine."
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Fishing Line As Artificial "Muscle"

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  • by Anonymous Coward

    I could have told them that, but I was too busy fishing.

  • They took a material with high tensile strength, coiled it, and annealed it into shape - and now it resists tension! Call Isaac Newton!

  • If you can prevent a person from overheating, you can keep them working 2-4 times longer. Muscles are bathed in blood, what coolant will be used for nylon? I suppose automotive stuff would be acceptable.

    • Heat isn't the limiting factor here, it's what causes the fibre to actuate.

      • Heat isn't the limiting factor here, it's what causes the fibre to actuate.

        Yes, but they will have to be cooled in order to de-actuate. The rate of thermal transfer is going to limit the working rate. It's fascinating stuff.

        • at this scale getting heat and coolant around the wire will be easy.
          • Sure, for a single strand. But actuators will be built up of multiple twisted strands, just like actual muscles.

            • by tmosley ( 996283 )
              He's saying that since the "muscle" is so much stronger, you need much less of it, so there is plenty of room for coolant. You only need 1% of the "muscle" mass as you would for regular muscle.
              • He's saying that since the "muscle" is so much stronger, you need much less of it, so there is plenty of room for coolant. You only need 1% of the "muscle" mass as you would for regular muscle.

                Nylon isn't as dense as muscle, and we'll want to do more work than a human muscle can do in many conditions.

                • Which - based on the implications, would require 1/100th of the muscle just to seek parity with a normal human muscle. So, it sounds like this should be quite easy to have it do much more work than a human muscle.

                • This is going to compete with hydraulic cylinders and pumps or winches and cables, not human muscles. Generating 220C for even moderate sized masses inside a living body is problematic to say the least.

                  Imagine an artificial heart made of this goo. It might pump blood well. But it would denature the protein in the blood while pumping.

                  • This is going to compete with hydraulic cylinders and pumps or winches and cables, not human muscles.

                    No, it won't. One of the nice things about hydraulics is that when you get the load where you want it, just shut the valve and it stays right there. And cables are easy to secure with a simple brake. This thing, on the other hand, requires you to keep pumping heat - and actively regulate it - to stay at the desired length.

                    There might be use for this thing, for example in a mechanically simple heat engine, b

                    • There might be use for this thing, for example in a mechanically simple heat engine, but it doesn't even remotely compete with hydraulics.

                      In those applications where hydraulics / winches and cables work - sure - but what about where they're a poor substitute for something that acts like natural muscle - like say - robotics?

                      Collaborator Professor Geoff Spinks says it is a much-sought breakthrough that could open the door to the use of artificial muscles in clothing and prosthetic manufacture, robotics, and as a green energy source.

                      - from TFA.

                      Notably - the article claims that the reaction is nearly as fast as human muscle - which could be interesting. Also, most of the practical applications listed in the article take advantage of the fact that the fiber responds to heat - which can include ambient temperatures, to automate the opening and closing

                    • I didn't say it would compete successfully in a general sense. Niche's at best.

                      It will not be embedded in biological systems. No artificial muscles, hearts etc.

                    • I think the key is that this has to potential to be much lighter weight and possibly less bulky than hydraulic systems. Prosthetic limbs and exo skeletons being a prime possibility for this kind of stuff. The only issue I can see is that they are talking about temperatures that would be dangerous for people. I believe those temperatures though are the point at which the material contracts to 50% of it's normal length. I suspect working with lower temperatures would work so long as you don't need that 50% ch

                • Perhaps but it would be near perfect for prosthetics. I doubt the control could be like a regular body part but for an amputeee, automatically bending a leg at the knee of folding the forearm in order to hold something while opening the door or whatever could make a dramatic difference for some.

            • Engines have been dealing with cooling and heating for years. Wear and tear on moving parts expanding and contracting should be ok.
              Values, joints and seals will break at the wrong time and leak over something they shouldn't.
              I found this - [] Role it up, stick it in concertina piping and run hot and cold air / water / oil / tea / beer/ over it.
        • Oh, I see. I assumed the original was asking how they'd ditch waste heat. So the real question is, how do you efficiently cycle it.

          • Easy. You add some double heat sinks. If those take up too much space try to make the reactor stronger so you can put some in there.

            Sure, it gets a tad more complicated if you want to build a brawler with triple-strength muscles or a high-output laser boat but if you keep track of your loadout's heat generation and maybe err on the side of cooling your 'mech should work beautifully even during heated engagements. (Pun intended.)

            Well, until you run into someone packing flamethrowers, of course. Or plasma
    • by Dunbal ( 464142 ) *
      [citation needed] I'm calling BS on this one. Heat is certainly not the limiting factor in human muscle contraction.
      • by Anonymous Coward

        He never said it was the limiting factor in contraction (power). He said it was a limiting factor in the duration of heavy work.

  • Mechanism (Score:4, Insightful)

    by symes ( 835608 ) on Friday February 21, 2014 @09:14AM (#46303175) Journal

    If I read this right - they coil the line, stretch it and then use heat to return it back to the original coiled state. This then provides lift. I am wondering how much heat is required though. If you have enough of these filaments in an artificial muscle arrangement could you, while lifting your car or running for the bus, spontaneously ignite? That to one side, though, I really love these unexpected breakthroughs.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      There are broadly speaking 2 varients mentioned in the paper, Nylon and Polythene. The Nylon was heated between 20C and 240C for full contraction, and the Polythene between 20C and 130C.

  • by BitZtream ( 692029 ) on Friday February 21, 2014 @09:20AM (#46303199)

    I've been using this property to tie flies since I was 5-7 years old ... 30 years ago. It wasn't new then. Admittedly, I never thought about using it or controlling it, but heat treating monofiliment isn't exactly new. Want a tight fly? Heat treat it, then give it a pinch to hold its shape after its good and warm. Use your fingers, not a tool that will nick the line and make it weak, as the heat treating already weakened its tensile strength considerably.

    Mono hasn't been around that long so I suppose fly fishermen hasn't been doing it that long either, but still, this property is well known.

    If only we had better search tools to be able to find things like this without rediscovering it. Its not wasted research by any means, but it sure does seem like we could make much more progress if we could benefit from the sum of human knowledge rather than the little bit we have domain specific knowledge of and trying to shoehorn everything else into it.

    • by Sockatume ( 732728 ) on Friday February 21, 2014 @09:43AM (#46303295)

      Suffice to say the process they used is a bit more nuanced than that; I can't link to the paper's figures because of the paywall, but they developed complex hierarchical microstructures of the filaments, and different ones for different applications. (E.g. one structure gives you a fabric with pores that open as it warms up.)

    • Monofilament fishing line [] has been around since 1939 and the most popular type that is used today has been on the market since 1959. Considering all of the uses it has been repurposed for in the last half a century, I wouldn't consider it new, except in a geological timeframe.

      Things like this discovery always make me laugh. People will make comments about how obvious this was. But it wasn't until the first time someone figured it out. Otherwise it should have happened sometime in the last fifty yea

      • I'm sure someone figured it out long ago and I'm sure fishing line has probably already been used for this purpose. This is just the first time someone was willing to swallow their pride and publish it in a scientific journal. I'm sure there are scientists and engineers out there saying "no duh" and "thanks captian obvious" to this article.
        • I'm sure someone figured it out long ago and I'm sure fishing line has probably already been used for this purpose.

          Why are you so sure?

          This is just the first time someone was willing to swallow their pride and publish it in a scientific journal.

          What pride? It's a legitimate discovery. With all of the dumb shit that gets patented these days, I'm sure someone would have rushed to the USPTO with it

          I'm sure there are scientists and engineers out there saying "no duh" and "thanks captian obvious" to this article.

          Why? With all of the research going into this field, you really think that something that works well and is cheap would be completely ignored? I think it's more likely that people had the knowledge that mono-filament line had these properties. But never thought that it would have the capacity to contract and relax with the amount of for

    • I don't think they rediscovered it. More likely someone is aware of it from fly fishing and they just decided to rigorously test it, and then take credit for discovering it. It's just good science.
    • I suspect this will become an increasing problem as the need for in-depth specialisation increases with the advance of the sciences.

    • by arielCo ( 995647 )

      Do you mean that the treated nylon re-twisted spontaneously upon heating? I already know that to make a tight knot on a stiff material you can soften it with heat, but this is about "shape memory" - twist, heat, relax; then it will coil up actively when heated:

      Spinks says they attached the fishing line to an electric drill and applied tension to the thread.

      As it twists, the fibre forms tight coils in a spring-like arrangement. Once heat is applied to the coils it permanently fixes that spring-like shape.

      Spinks says to use these springs as artificial muscles heat is again applied, causing the whole coil to contract.

    • So you would place humanities needs before the needs of Intellectual Property Lawyers?
    • by ceoyoyo ( 59147 )

      Heating plastic to make it shrink or hold a new shape isn't new. Getting it to cycle from shrunken to unshrunken and back is.

      • I don't think it cycles back. I didn't see that in the article. Just that in the lab you stretch it under heat. wait to cool, then when reheated it can shrink again, one time (or perhaps more if you take it back to the lab and repeat the stretch/heat). I got the impression that once it cools after it has contracted it is then set at the contracted length.
        • by ceoyoyo ( 59147 )

          The article describes heating the filament to set it, stretching it back out, then heating it again to contract. Fly fisherman (and kids with hairdryers) only do the first part. In the paper they describe:

          A coiled nylon 6,6 muscle delivered over 1 million cycles during periodic actuation at 1 Hz (Fig. 3B), raising and lowering a 10-g weight producing 22 MPa of nominal stress. This actuation was powered by applying a 30 V/cm square-wave potential (normalized to coil length) at a 20% duty cycle. Although th

    • But they haven't measured and documented it. So it wasn't science, it was hearsay.
      There are a lot of truths out there that science hasn't gotten to yet. Heck only a few years ago they calculated how scotch tape rips.

    • How did you reheat the fly to 220C while casting? And why?

      You're not referring to just softening the plastic to shape it, are you? That's not what the article is talking about. The article is talking about setting it up so that it moves back and forth based on temperature. You heat it up, it shortens. When you stop applying heat it lengthens.

      • Heat monofiliment, it shrinks, twisted or not. Twisting it just means you can make more of it shrink in a smaller space. When wrapping a fly, you get it nice and tight, then heat it to get it to shrink and be even tighter. I pinch it at this point as it seems to hold its shape better.

        I'm not claiming I'm doing something special, its just sad to see that this was 'discovered' by someone, when humans already KNEW about it, its just the information wasn't transferred from the people who know about it to th

  • "So tell us again, Lefty, how you got that friction burn on your pecker."

  • "...we're not just JUST about FTP servers anymore!"
  • Strain and exposure tends to destroy nylon from my experience, when a muscle fiber is broken it gets replaced by one or more new fibers, how would you efficiently replace broken coils on a artificial limb?
    • Just order a new artificial muscle replacement pack on line. The huge break through here is that the materials area already commonly available and ridiculously cheap in the form needed. $5 for 1Kg of fishing line. Most of the stuff people have been testing for this kind of application are only really workable on tiny scales and use exotic and hence expensive materials.

  • by MobyDisk ( 75490 ) on Friday February 21, 2014 @10:31AM (#46303551) Homepage

    Most artificial muscles work by applying electric current along the muscle. When the current is removed they snap back to their original shape. Using heat sounds very limiting. Presumably you cool it to get it back to the original shape, but the ABC article is light on details.

    • Using heat sounds like it won't work very well in different environments. What happens when you try to use your artificial limb in subzero temperatures?

      • by Anonymous Coward

        Using heat sounds like it won't work very well in different environments. What happens when you try to use your artificial limb in subzero temperatures?

        You've probably got that backwards. It's easier to heat an object than to dissipate heat. A cold environment would make cooling more efficient, but a hot environment would reduce that efficiency. In extreme cases where the ambient temp is at or above the max operating temp of the fiber you'd never be able to get it to change back to neutral shape.

        • Yes, but being able to heat that object properly in a very cold environment depends on having very good insulation so that the heat isn't dissipated to the environment too quickly. Then moving the artificial limb to a hotter environment, with all that insulation still present, means you need to have an active cooling system for it to continue working, meaning the whole thing is now pretty complicated. Finally, generating heat in a precisely-controllable manner (given these challenges of insulation and coo

    • by ceoyoyo ( 59147 )

      Actually, a lot of artificial muscles use heat. The heat is often provided by running an electric current. You could do the same with these. Electric heating wires for contraction, liquid cooling capillaries for relaxation.

    • I thought most of the electric muscles worked by having the electricity heat part of the alloy? Sounds like the same mechanism, they just need to find an easy way to do the heating outside of a lab (muscles sealed in a tube of fluid may work).
  • And therefore cannot be any sustained energy output. Oh sure, there's doubtless energy in the taught cables... but not enough to call it a muscle.

    What they have here is a plastic spring. It can hold large weights? Amazing... Fishing line does that especially if you use a lot of it.

    Am I missing something here? It seems like its just a spring to me. A spring is not a muscle.

    • Heat is the input energy. It takes heat to actuate the muscle. After it cools it stops resisting the tension. My guess is that heat is applied through nichrome wire. Although being able to actuate at 130c makes me think you could use polyethylene coils to make a waste heat recovery engine via a reciprocating pull on a flywheel

      • ah, that makes more sense. So you heat the wire and it relaxes... cool it and tightens up?

        • I might have gotten it wrong, but my reading of the article was that heating is actually what causes the spring to retract back into it's coiled shape, when it cools it relaxes.

  • Funny, if you happen to be Russian and of that generation - this is pretty much how "bioplastic" drive was described in a sort-of-science-fiction book about "Neznaika in a sunny town" :) Here is the relevant page:

    I've been waiting for this one for a while.

  • by PPH ( 736903 ) on Friday February 21, 2014 @12:21PM (#46304335)
    Gone fishin'^H^H^H^H^H^HThermo-mechanical materials property researchin'
  • News Alert: Fishing supply stores across the world are being mobbed by crowds of fidgety nerds buying up all the fishing line their moms' will let them buy.

  • One of my personal long standing predictions has been that when we finally get really cheap "good enough" robot muscles, personal robots will take off much like PCs did, even if the muscles have significant problems to be worked around.

    I presume that with use these muscles will stretch and lose strength. But that's OK - just pair them with control software that adapts automatically. If the muscles get too weak, replace them. The main question will be how fast they degrade. If they could last in an int

    • It seems to me that the bigger barrier is computer vision and AI issues, and I would say that as some of these things are getting closer to solved robots are very close to the "take off" point... it's arguable that it is already happening. Servos and electric motors are pretty damn good (and cheap!) and easy to control - artificial muscles have a lot of improving to do to match that. That said, the kind of uber-flexible humanoid robot that most people envision might be easier to realize if artificial muscle

Computers are unreliable, but humans are even more unreliable. Any system which depends on human reliability is unreliable. -- Gilb