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Advances in Artificial Muscles Using Plastic
pinglej writes "According to this story on MSNBC, Scientists at SRI have made some advances in muscles made using strained plastic that are more responsive than natural muscles. Has lots of neat applications from speakers to artificial limbs. " I think the best idea is to make me the strongest man alive - it'll be better than cybernetic body armor!
" I think the best idea is to make me the strongest man alive - it'll be better than cybernetic body armor!
Except that you'll snap your bones like dry twigs or pull of bone chips at the attachment points.
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It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Materials like this exert force because they try to maintain an approximately uniform density, so an electric potential squeezes it into a different shape. The trouble with using this to do mechanical work -- like the "artificial muscle" this is being hyped as -- is that you can't exert very much force before the material starts to compress, or else you overwhelm the electrostatic forces. This is sort of the converse of the problem that piezo-based transducers have always had: the electrostatic potentials cause the crystalline lattice of a piezo to expand with considerable force ... but only for a few hundreds of microns, at best. Which makes them good for speakers, or ultra-fine positioning, but not so good for doing work.
As far as I can tell, the most promising avenue for these materials would be to use them rather like small, agile hydrolic pumps that have large dynamic range but little pushing power and even less pull. The comment in the article about an artificial butterfly could be insightful with respect to what you could do with these. As far as artificial limbs go, unless they can dramatically increase the force they can put out, they might be a major breakthrough for actuating the fingers of a prosthetic hand, but they'll be no good at all for replacing the wrist flexors, never mind a bicep.
I would suggest that researchers look for a way to turn this effect around, allowing the material to pull rather than push. Such plastics almost invariably have greater tensile strength than resistance to compression, and it's much easier to engineer around, too.
Quantum mechanics: the dreams that stuff is made of.
Yeah - the 'perfect' speaker cone/dome/panel is infinitly light and infinitly rigid. I have trouble picturing a flexible substance with that kind of rigidity(word?). The sound producing substance is not usally the magnetic part (paper/kevlar/aluminum), there's usually a coil of wire surrounding a magnet... the coil is attached to the non-magnetic substance, which then moves and produces the sounds...
I agree, though... can a piece of plastic/sillicone really exhibit these characteristics (especially with flat response throughout the audible band)? It's hard to say... it just doesn't seem that the electric response would be the same over those frequencies...
"It's tough to be bilingual when you get hit in the head."
So we must be about two years away from implanting a weapon directly into people.
We are getting too close to BORG time in my opinion.
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Granted, artificial limbs would be a great application for this, but even better would be to enhance our own abilities, like the japanese mechs. We can either be encased within a sheath of the stuff, complete with high strength artificial exoskeleton, actuating the robot with our own movements, or we could (gasp!) actuate remotely.
We would create strands of this stuff, bundle them together into an artifical muscle which can then be wrapped with a material live Kevlar, which will protect it, and has some flexibility. We could then add tough armor outside of it to protect it from direct damage.
if we were not the peace-loving people that we are, we could create an army of these, send them over to any hostile area, and destroy the crap out of people, and never risk the life of a single American soldier (which the American public always gets all worked about).
Or, we could use it to build prostheses for veterans who may have lost their limbs in battles because they had to be there in person.
Recently I've been wondering about the possiblilty of using a chained array of solenoids as an artificial muscle. The shaft of the solenid could pull on the chassis of the one infront of it, providing muscular pull. The ones I've spected on some of the web sites have a pull of about 5 lbs. A quad can push 350+ Lbs.. so to make a leg strength musclce would require 60-70. Expensive but do-able. The best parts is the solenoids are responsive to varying amounts of currents.
Anyone with more electronics knowledge care to comment
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My first contact with the concept of an artificial muscle started when Prof. Jonathan W. Mills from Indiana Univ. gave an IEEE talk at my college around 1992. When he demonstrated the foreshortening of a small nickle-titanium (nitinol) heat actuated leg all the geeks in the auditorium were impressed. (College profs included)
We had a small lab session where we made the legs from materials he brought and did a Q&A session. I still have that device around played w/ it 2 nights ago. Didn't have a battery around to run current through the nitinol wire to actuate it (the electrical resistance generates enough heat to contract it), so I held a lighter about 6" underneath to test it out. Still worked like a charm.
If you are interested in looking into this thing, I'd suggest hitting
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The reason that speakers nowadays use magnets is because its the easiest way to convert electrical energy into mechanical (vibrational, ie. sound) energy. The electrical signal passes through a coil that is in a magnetic field... this causes the coil to become magnetically charged and get attracted or repelled by the magnet, moving the cone (this happens at high frequency, causing a back and forward movement of the coil (which is attatched to the cone... which moves the air at that frequency ... which makes you hear the sound))!
Now... back to the plastics. If we could us a plastic to move a cone (or just itself) in response to an electrical current, then we eliminate the costly, heavy and bulky parts of a speaker (the coil and magnet). SO... yes this can be used to make potentially high quality speakers!
i wont even bother to comment on your "30Khz point" because it is completely illogical.. you would want it to vibrate at different rates, ranging from a few times a second to nearly 20000 times a second in order to cover all sounds that the human ear can hear.
1) I read some guy saying "Plastics melt" (among other "weaknesses")- ok, we're not talking saran wrap or the stuff they make pens out of here... the word of the day was "Acrylic"... some polymers can be made to withstand tremendous heat/strain/environments...
2) When they say "muscle"... it doesn't necessarily mean they've got to put it in a human body. They could mean for use in a machine - and muscle is the best word to describe how it works... (Robots, exoskeletons, automatic door closers...)
3) If they were developing it for the human body, it would have to be developed in a tested and controlled fashion. Allowances for added stress would have to be made (re-enforcements to skeletal structure) as part of the design/engineering of the product. Otherwise, the muscle would need be developed to not exceed the strength of the skeletal structure. (beyond the fact that I seem to remember that when bones are stressed they emit a small electrical signal - which would cause these "muscles" to stretch and relieve the tension...)
Don't just look for nay saying ways to FUD the product... any idiot can point out problems... if you were really smart, when you found the problem, you would make a suggestion on how to fix it.
BlackNova Traders
Gee, I'd like to hear speakers that really sing.
After all, how often do body builders break bones? I mean, it happens, but it's pretty darn rare. In fact, muscle tears are far more common than broken bones, and that risk would go away.
... you could use a screw and drill it all the way in
Body builders build bone as well as muscle. The skeleton is an amazing adaptive system -- heals in bone such as at an old fracture point are stronger than virgin bone. When you engage in weight bearing excercise and you create microfractures in your bones that heal into a network of stronger bone. This way, the skeleton adapts to actual patterns of use, becoming strong as needed while remaining light as possible.
Stress fractures happen when you don't give bone time to heal or when there are hormonal problems. Thus, somebody who is taking steroids to reduce his recovery time for muscle building may risk getting stress fractures, as well as women who exercise to the point where they stop menstruating.
In any case, since you won't be perceiving any muscle strain or pain from exercise, there's an excellent chance that even if the bone can bear the force initially, that you'll be getting some stress fractures pretty soon. The secret of exercise is that the benefits come from the rest that follows.
The stresses around the screw would be terrific; perhaps if you slowly ramped up the force the bone could adapt, but it is unlikely to be as strong as something which left the bone intact, like some kind of artificial tendon.
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To a certain extent, you could do it by "reversing the plugs" -- for example, have the bicep-replacement recieve the signals intended for the tricep, and vice-versa. Of course, relaxing both muscles would cause a double pull instead of a double relax, so it'll be a lot more sensible (at least during early stages) to use it in artificial limb replacements instead of for augementation of existing limbs.
As a heart replacement, logically one would also embed a pacemaker-like device either to control or convert singnals so it would pump correctly...
(just don't let Microsoft install Universal Plug & Play on the thing...)
Steven E. Ehrbar
Get away. They're in it together. In fact it's probably the same guy arguing with himself, I've seen it before on Slashdot only recently. In fact, it's probably YOU!
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but, ha ha ha ha, your reply *did* make me laugh out loud.
Consciousness is not what it thinks it is
Thought exists only as an abstraction