• (none of my text posted that was after the link above, sorry)

    I bought some fishing line and was playing around with this last night. It is legit. I'm going to make some weird moving art with it. I also plan to play with it in a solar/gravity motor experiment that won't work. But on to the biohacking applications...

    Besides muscle, this could be useful in temperature sensitive feedback projects. I am confused about the thermodynamics involved here though. In the setup where heat causes the line to shorten and lift a weight, am I right in thinking that heat is being converted into work? If so, could this have any significant use in heat absorption? 
  • @directorX do you know what temperatures it responds to? And have you tried the silver coated nylon thread yet?
  • I did the annealing process with a hair dryer, so it doesn't require too much heat. After that, the line responds in relation to the amount of heat applied. So to get back to the original annealed shape I need to get it at least as hot as the hair dryer. It responds to much less heat, of course. Applying a little bit of heat will cause it to bend half way, a little more heat gets you to 3/4, etc.

    I have annealed pigtail lines that scrunch up when warmed and also straight lines that straighten out when warmed. Maybe I'll try to make a video tonight.

    I didn't do the silver. I was planning on just painting some of them black today so they could soak up some heat from the sun. I'm going to put a pigtail line with a weight through a vertical pipe. The bottom of the pipe will be open so the weight can drop out of shade. Hopefully the sun can then heat up the line and cause the weight to raise back into the shaded area, which cools and starts the process over again. 

    The article mentions infrared light, and I'm wondering if they are coating in something that reflects everything except for ir light to get that response. If so it could be used for a lot of cool sensors maybe.
  • @DirectorX the basic idea of heat beeing converted into work is right. The process is still limited to the Carnot cycle limitations. So the energy you can get out of it is rather low compared to what you have to invest into heat. But if heat is available in huge amounts, like from the sun, it can make an ok converter from heat to mechanical energy.
    I ordered some thicker nylon for higher power applications. It should arrive soon.
  • Ok, that makes sense. How thick is the nylon you ordered? Also, do you think the annealing temperature is much higher on the thicker line?
  • The nylon i ordered is about 0.7 mm diameter. Thicker options are available and if i get it to work, i'll give them a try as well. The temperatures should be depending on the material itself, not the thickness. So you may need to hold the temperature for a longer time so the material heats up to it throughout.
  • Superstrong versatile muscles made out of standard fishing line!? Just how many falling stars did you wish on, @DirectorX ?

    Any updates on projects using these? I might suggest them to my flatmate (an architecture student) who has access to a workshop for making his models, if you've got any suggestions on the best way to do this.

    Also, the article seemed a bit vague on whether they could be triggered by other things than heat (or electricity producing heat), since that's not the best thing to be varying wildly if anyone develops something implantable.

  • @Nightgaunt I gave it a test run with different materials I had around. the 0.7mm Nylon I mentioned turned out to not have a perfectly round, which made coiling it up pretty difficult. But with a lot of manual coiling, it worked out. Made several smaller coils and run a quick test on them and it turns out they work pretty well.
    Biggest drawback is that only are triggered by heat only (no matter where it comes from). And the only real way to get them act in a fast way is by submerging them in hot/cold liquids.
  • Hmmm...  I wonder the maximum temp allowable. I doubt a nichrome wire would work, but maybe at low voltage? Or alternatively, copper tubing carrying either gas or fluid? I think we'd need to check out the operating temperatures before failure before proceeding further. Too cold = brittle, Too hot= melt/failure.

  • So this stuff is just straight up monofilament fishing line? Nothing fancy for the basic concept? 
  • Also, what is the length of extension and retraction occuring? Are we talking an inch or a foot? Can we convert that to cm/degree C or something? We'd need to check out the angle which would still allow for contribution to movement. When you wrap a rope for example a few times around a limb, it no longer works as a pulley r/t friction. Think of your joints - your elbow for example - Bicep Brachii originates up by the scapula and inserts somewhere down by the Radius. What is that? A foot? 2?  (Varies by individual). My point is that if you place your finger on the aproximate insertion point and then flex your elbow, you can figure out around how much actual contraction of muscle length going on. If we can't achieve something similar, we'd need something like a pulley or angled approach to achieve similar movements.
  • @TheGreyKnight correct. The basic concept also work with a variety of different polymers and is not even limited to monofilaments. Even tho monofilaments appear to maximize the effect.

    For electrically activated , high-temperature-range muscles you should look out for carbon-nano-tube . It seems that simmilar mechanism also work with those, except it acts a lot faster.
  • edited May 2014
    @DirectorX You mentioned annealing the line. Could you describe how you did that? And did the mono-filament want to uncoil after you annealed it? 

    Also, looking at the original article, I saw other configurations for the muscle fibers. Has anyone here tried these out? Or have we all stuck with the coil config? 

    I found a couple of good resources that have a bit more data on the concept as well.

  • The journal article:

    Artificial Muscles from Fishing Line and Sewing Thread

    has been added to the community whitepaper folder
  • Sorry for the late replies.

    @TheGreyKnight Annealing was basically just using a hair dryer. I made a video but it sucked and I deleted it, sorry. To make the coiling I just attached it to a drill and slowly wound it up until it pigtailed. Then I used the hair dryer to anneal it. I've since read other things on annealing that call for multiple heatings to maximize the effect, but it seems like it was dependent on what kind of material you were using. The coiling relaxed a bit after it was annealed, but a weight was used to straighten it out again. Same was true when I annealed the line straight.

    @Cassox As far as the ratio of length goes, it does contract quite a bit using just a standard single pigtail. I'd guess 3:1, possibly more. The amount of weight it can lift is not so encouraging though. A few house keys maybe from a single line.

    It is fun to play with and definitely worth the $3 investment. Somewhere on the interwebs I found an experiment involving fishing line used in series vs parallel configurations that was interesting and I've been thinking of playing with that but haven't really got around to it yet.
  • Not to be a thread-necromancer.. 
    But i kinda want to know if anyone had some success with these?
    I have, kinda.. But im having problems with heating/cooling fast enough..

  • My tip would be to not use a heat based artificial muscle system when you need fast actuation.
    Electrostatic, carbon nanotube based ones are currently state of the art. They are not quite as easy to build at home and require high operating voltages but they are fastest and super strong.
    Electroactive polymers may be a good choice for you to play with. Most still require high voltage but you have to bite one bullet anyway.
    Then there are gel-based types. They tend to wear down faster but work based on current rather than high voltages. 
    The world of actuators is big, worth exploring.
  • I'll second that. the fishing line stuff is super disappointing. And really slow. good for passive systems or something that doesn't need to move quickly. Which don't get me wrong is still cool, but for anything like a prosthesis you need nanotube wire
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