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Biotech Robotics News

Nanotube Muscles Are Strong As Steel, Light As Air 103

Al writes "Scientists from the University of Texas at Dallas have created nanotube-based artificial muscles that are light as air and work even under extreme temperatures. The 'muscles' expand width-wise by about 200 percent when a voltage is applied, but are stronger than steel lengthwise. The nanotubes within the fiber naturally stick together. Applying a voltage makes them obtain a charge and repel one another. The researchers created them by stretching bundles of entangled carbon nanotubes into long threads. Several cool videos show the strange stuff in action. Some experts, including one from NASA, believe that the nanotube muscles' ability to withstand extreme heat and cold could make them suitable shape-shifting materials for future space missions."
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Nanotube Muscles Are Strong As Steel, Light As Air

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  • Little bit hyped. (Score:5, Informative)

    by zymano ( 581466 ) on Saturday March 21, 2009 @04:28AM (#27277639)

    From Article -

    However, electroactive polymers generate up to eight times as much force per unit area as the nanotube sheets. "For artificial muscle, you need a large change in force coupled with a large change in length," Hunter says.

    Polymer actuators also need just a few volts to contract. The ribbons, in contrast, require three to five kilovolts, which Hunter says is too high for use in humans and higher than ideal for robotics.

    • Re: (Score:2, Insightful)

      Good point, but I am sure that they can shrink those energy requirements... Didn't computers use to be the size of a room and take up a hell of a lot of energy....
      • trying to recreate muscular movement seems more similar to using amplification of low signal levels to drive loudspeakers than to reducing thousands of pcb's to a few ic's to make a pc

    • Re:Little bit hyped. (Score:5, Interesting)

      by Instine ( 963303 ) on Saturday March 21, 2009 @06:50AM (#27277963)
      I think you're right that this will never produce the forces required for most 'muscle' purposes.
      However if it holds its charge it could be very exciting in terms of capacitance!
      I've been playing with synthetic muscles, and I believe magnatism id the only likely way forward. But that Nanotubes are the solution. Esspecially if submerged in ferro fluids, or paramagnetic liquids (e.g. liquid oxygen, though that would not be great re safety). I've already had a bash at simply using thin wire: see vid of lego coil maker [youtube.com] and seen here [talklets.info] for brief comments.
      • Your magnetic field strength will be limited. What use is a robotic hand that can't use metal tools?
      • Re: (Score:2, Funny)

        by osvenskan ( 1446645 )

        I've been playing with synthetic muscles

        Is that you, Barry Bonds?

      • by owndao ( 1025990 )

        It appears to me that the fibers are repelled from one another by their electric fields just like some person with long hair touching a high-voltage, low current source like a Van de Graaf generator. Some equations that might be of interest are:

        force x distance = work so yes, in order to perform work a muscle must be capable of applying a force over a distance. Either the force or the distance can be large as long as the sum of their product over the distance moved ends up large. The electric field force i

  • What wasn't apparent to me is whether these "muscles" are exerting force along the axis of their attachment points; are they pulling against the "bones" to which they're attached as they expand laterally, perpendicular to the axis of attachment?

    If they're not, I don't see how these structures can be described as muscles.

    • by ortholattice ( 175065 ) on Saturday March 21, 2009 @05:24AM (#27277755)

      What wasn't apparent to me is whether these "muscles" are exerting force along the axis of their attachment points; are they pulling against the "bones" to which they're attached as they expand laterally, perpendicular to the axis of attachment?

      All three articles are confusing and lacking information needed to make any sort of meaningful conclusion. It seems the people writing them don't bother to think, but just string together random fact snippets that sound cool and generate hype.

      One puzzle is that on the one hand, "carbon nanotubes are highly conductive", yet on the other hand need "three to five kilovolts" to contract. If the resistance were say one ohm, that would be 9 to 25 megawatts of power! A robot with 50 muscles might consume the entire output of a power plant, not to mention burn up instantly.

      They also confuse the force exerted lengthwise (large) and the force exerted width wise (possibly very small, since it seems to be due to electrostatic repulsion - the videos do not show the width-wise force being measured or demonstrated).

      Possibly the 1% lengthwise contraction could be amplified, to say 30% by wrapping it around a set of 30 pulleys.

      • Single wall carbon nanotubes can be coated with various chemicals (I forget the details), to make them act as batteries/capacitors. When you charge the nanotubes they also change shape at a molecular level. This helps with the power requirements, since at least some of the energy would be recovered as well.

        I can't be sure, but this is how I've always assumed artificial muscles would be made if they used nanotubes.

      • by vix86 ( 592763 )
        I looked at the actual article in Science magazine and there were a number of formulas mentioned for showing the amount of energy that has to be applied to this. I'm not a physicist so some of these don't make much sense to me, but maybe it'll interest someone.

        The article mentions that Epsilon_w (Strain?)= the change in Width / initial Width_0. The change in E_w increases quadratically(V^2) with voltage applied, but at higher voltages the increase in E_w increases with V^(2/3). They mentioned that to get
      • by owndao ( 1025990 )

        "One puzzle is that on the one hand, "carbon nanotubes are highly conductive", yet on the other hand need "three to five kilovolts" to contract. If the resistance were say one ohm, that would be 9 to 25 megawatts of power! A robot with 50 muscles might consume the entire output of a power plant, not to mention burn up instantly."

        That assumes that there is no imaginary component involved. I think that the should have a non-zero self-inductance similar to a wire so high AC voltage would not conduct as re

    • by Quothz ( 683368 )

      What wasn't apparent to me is whether these "muscles" are exerting force along the axis of their attachment points

      Plenty of force, but not much distance:

      The hardness comes in because this material is inelastic along its length. Whenever the material stretches in width or thickness, it contracts in length, but only by a few percent. It can't stretch in length because it's extremely rigid in that axis and can generate an isometric stress (isometric means without changing shape) of 3.2 MPa, which is 32 times more than the sustainable maximum for skeletal muscles.

      • by macraig ( 621737 )

        Ah... so then in practical use as "muscles" this material would have to be attached MUCH closer to the joint than would a human muscle, and perhaps the joints would have to sized disproportionately; attaching it closer to the joint effectively amplifies the effect of its more limited degree of elasticity. I think.

    • by owndao ( 1025990 )
      I believe that the fibers are repelling one another as I stated above. Other evidence that they pull while puffed out is that their relaxed state they appear to not repel one another as is shown when the long strands are pulled from the spool. Ever stacked a bunch of disk magnets? they tend to want to form a rod and are very difficult to pull apart lengthwise but bend easily. I suspect the stacked carbon rings behave similarly.
      • by macraig ( 621737 )

        That's a good analogy, if true. It won't matter much beyond the curiosity value of it, of course, until I can buy my first affordable nanotube exosuit.

  • Very interesting technology.. but the article doesnt talk about how it can be used for artificial limbs (the 'muscle' in the name).

    It would make for more flexible artificial arms than the current available robotic limbs, given the flexible nature of the nanotubes. Not to mention very powerful.

    • Re:Human body uses? (Score:5, Informative)

      by oneirophrenos ( 1500619 ) on Saturday March 21, 2009 @05:05AM (#27277713)
      Real muscles contract by myofilaments sliding past each other, shortening the overall length of the muscle. In this case no sliding past occurs, and the overall length of the nanotube "muscle" doesn't diminish, so I can't see how this technology could be used to replace actual muscles.
      • by ardor ( 673957 )

        Easy: replace the entire arm.
        Though it would look weird when your arm has "made in china" written on it.

      • Re: (Score:3, Interesting)

        by vikstar ( 615372 )

        Real muscles contract by myofilaments sliding past each other, shortening the overall length of the muscle. In this case no sliding past occurs, and the overall length of the nanotube "muscle" doesn't diminish, so I can't see how this technology could be used to replace actual muscles.

        It can be used to replace muscles due to something called Poisson's ratio [wikipedia.org], which is very high for the nanotube muscle. This effectively does allow it too shorten the overall length.

  • Where's my Battlemech?

  • Why almost everything is needed to aim for space or war? Okay, those two areas has most of the money for development. But be a real, this kind technology could help humans. Old people, paralyzed people and those who has lost their limb.

    And think how much this would help in the situations where you can have a "suit" like for construction sites etc, helping for heavy lifting. I believe many is now thinking "Crysis nanosuite" but it would not be a far away from truth what to get, not just for wars but for in r

    • Re: (Score:1, Insightful)

      by Anonymous Coward

      You are comparing space and war? Space technology helps humans. In some cases it may only pay off in the far future, or only pays in knowledge of the universe (if you don't think that's a worthy goal, go back to Westboro), but there is plenty of space tech that's fundamental to the modern life. Satellites of all kinds, without them forget about communications, weather satellites, geologic survey satellites, etc.

      • by Fri13 ( 963421 )

        Yes, Space technology helps humans. But you do not need to move all technology to space first before it can help humans on earth.

        Lots of different kind things is invented in space. And some only in space. But same thing is for war. Somethings are only invented on war times, like nuclear power.

        We could just focus these developments for daily usage, without need to spend so much money and time to fight each other or dream how to help to build a "camp" on the Mars etc.

        In this case, why this technology should o

    • by emilper ( 826945 )

      Let it to the army ... imagine hordes of grumpy old senile gramps walking through walls in their armored ('cause you'll need armor with muscle strength * 32) power suits, squishing unruly babies and going to vote ...

  • by wisebabo ( 638845 ) on Saturday March 21, 2009 @05:16AM (#27277733) Journal

    The fact that it is "strong as steel" and "light as air" seems to me like it could be made into a (very) big net that, when launched into orbit could capture space junk. Hopefully the fact that it stretches 200% could mean that it would have enough elasticity to absorb some of the kinetic energy of the space junk.

    As long as the space junk didn't make holes in it, it would slow the junk enough so that they would fall out of orbit quickly. (Maybe the impact of a lot of junk would require periodic re-boosting of the net, I don't know.)

    Another idea would be to use AEROGELS. This super lightweight material has already been proven to slow down hyper velocity objects (admittedly just particles) in the spacecraft "Stardust". The main problem with aerogels would be launching it into orbit, although it is very light the necessary volume required would be huge. However, if it could be manufactured in space then just a small amount of raw material could make a gigantic volume of the stuff.

    • by spazdor ( 902907 ) on Saturday March 21, 2009 @05:42AM (#27277809)

      If the net is light as air, then how exactly is it going to absorb the junk's momentum?

      More reasonable guess: space junk hits net and continues along its previous trajectory, but now with a virtually massless net trailing from it.

      • Re: (Score:3, Interesting)

        by wisebabo ( 638845 )

        The net, overall will be very large and weigh thousands of kilograms or more and will definitely absorb the smaller fragments with impunity These little fragments could otherwise be the hardest to "catch" in a reasonable fashion because they are so numerous and multiplying the quickest after every collision. Also, if you slowly spin the net, it will remain open and not wad up.

        You are right about the really large "fragments" (boosters, complete satellites) however they are relatively few in number and coul

      • Re: (Score:1, Insightful)

        by Anonymous Coward

        More reasonable guess: space junk hits net and continues along its previous trajectory, but now with a virtually massless net trailing from it.

        ...Or given the speed most "space junk" travels, it'll just:
        - make a nice hole in the net
        - explode into even more, smaller, and harder to track objects
        - and keep going

        "Stronger than steel" doesnt mean anything at 16000mph

        • Who knows? I don't, I'm neither a physicist nor do I know anything about the material's properties (or whether they can be improved upon sufficiently). I wish someone more qualified would point out the "holes" in my suggestion!

          What about my aerogel idea? Again, if you could put a really huge block of it in space (it would have to be able to be manufactured there) wouldn't that work as well or better?

    • How about using that net for solar sails? Maybe take advantage of the material to provide solar energy to the spacecraft (the material is supposed to be conductive)?
    • Screw that. I want my memory cloth Batman cape!

  • I see the threads aren't perfect individual nanotubes, but still, good enough for a tether maybe?
  • How long until it's in hobbyist hands?

    I want one of these: http://www.sarna.net/wiki/Marauder [sarna.net]

    Failing that, how about http://www.sarna.net/wiki/Turkina [sarna.net] or http://www.sarna.net/wiki/Dire_Wolf_(Daishi) [sarna.net]
    But a http://www.sarna.net/wiki/Locust [sarna.net] or http://www.sarna.net/wiki/Kit_Fox_(Uller) [sarna.net] would be fun too.

    Any way, new toys for robotics are always fun.

  • This means i could... like... get a nano-internet jammed in my arm or leg?
  • Hair also repels one another when given a voltage:
    http://images.google.com/images?q=hair%20static%20electricity

    How is this different, and how will it make a muscle? It didn't seem to make anything shorter in the direction where it's actually strong.

  • Story look like Battletech Myomer development

    http://star-league.org/myomer.html [star-league.org]

  • Now instead of rogue nasa 100K floating toolboxes, we can have rogue 10M floating toolboxes! Great, I'll enjoy the all those cool I-can't-reach-it-is-floating-away videos;)

  • seems like all the pieces to a crysis nano suit are coming together, invisibility and strength in japan, armor in us :/
  • by Anonymous Coward on Saturday March 21, 2009 @07:07AM (#27278015)

    ...as asbestos when inhaled...

    • The artificial muscle was not designed for rapid continual surface abrasion. Not without a proper external protective sheath.
  • What is strength? (Score:4, Insightful)

    by Anonymous Coward on Saturday March 21, 2009 @08:09AM (#27278221)

    Pure tungsten is about eight times as strong as mild steel -- the stuff that your car, refrigerator, and computer case are made of -- in terms of tensile strength. It's also very tolerant of high temperatures.

    But because of its brittleness, it's useless as a structural material. Why do these articles always refer to strength, without describing what kind of strength that is? Tensile, compression, shear, torsional, etc.

  • The writer confuses 'stronger' with 'higher strength to weight ratio'. Steel is still stronger. And since this is an artificial muscle, 'tensile strength' as a material property has nothing to do with muscle force.

    Carbon nanotubes are only strong with tensile forces. Compression and lateral forces causes them to quickly buckle and bend.

    That being said, 2x extension change is pretty impressive!

  • Myelon Fibers?

  • by Animats ( 122034 ) on Saturday March 21, 2009 @10:38AM (#27279119) Homepage

    From the article: The new actuators, on the other hand, expand by up to 200 percent but generate small forces per unit area, making them less than ideal for many applications, including robotics.

    What is it with these crap materials science articles? We keep seeing articles about some new material with interesting properties, but not good enough to be useful, touted as a major breakthrough expected to show up in products Real Soon Now. This crap keeps showing up in MIT Technology Review and in Science, which used to be respected publications. It's fine to publish the materials-science results, but not with the press-release hype.

    The "robot muscle" problem is well known, and many attempts have been made to address it. There's no good equivalent of biological muscles. There are several materials that are promising in theory, but not useful in practice. Electrorheological fluids [wikipedia.org] have been tried, but none of them work well enough. Shape-memory alloys used to have a fan club, but they don't change shape by much, and the electrical power inputs are high for the mechanical energy out, because the power is used to heat up the material and cause a phase change.

    Robots still use pneumatics, hydraulics, and electric motors, with the occasional magnetic-particle clutch.

  • The 'muscles' expand width-wise by about 200 percent when a voltage is applied, but are stronger than steel lengthwise.

    We don't make sense, but we sure like pizza!

    I know this is Slashdot, and everyone's busy scripting a botnet or something - but why do so many submissions fail to demonstrate even basic English competency? This is a mistake the average fourth grader wouldn't make. Plus - shouldn't the "editors", oh I don't know, edit these submissions?

    • i'm not sure i see the problem w/ that sentence. i agree the semantics are fuzzy, but the sentence structure seems fine. you mean the apples-to-oranges comparison of expansion in one dimension and "strength" in another ?

  • Well, I for one welcome our new Carbon Nanotube strong-arm robotic overlords.

Keep up the good work! But please don't ask me to help.

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