Electro-active Polymers

What’s that you say? You’ve got rigid materials that change their shape when exposed to electric current? Sign us up for some! Although the fabrication process looks a bit daunting, we love the results of working with electro-active polymers. These are sheets of plastic that can flex by contracting in one direction when the juice is turned on. It has an effect very similar to muscle wire but distributed over a larger area.

From what we saw in the video after the break it looks like this is not the most resilient of materials. Several of the test shots have broken panes, but we’re sure that will improve with time. It looks like there is some info out there about fabricating your own EAP but the processes seem no easier than what’s going on at the research level. We might stick to building our own air muscles until EAP is easier to source for projects.


[Thanks Kristoph]

22 thoughts on “Electro-active Polymers

  1. If made as a bunch of strips it may work as “muscle” fabric … not sure what the strength and power requirements are though… but looks very interesting one application I can see is possibly to alight solar cells to the sun for best extraction…you would use the provided energy to keep the alignment but again not knowing how much it takes its hard to tell if added efficiency is worth it.

  2. good for energy-harvesting from a flag flapping in the wind? would obviate the need for complicated windmill setups (surely for smaller power requirements).

  3. well I guess that for the moment since it’s hand made with “fragile” materials it won’t likely be able to lift anything but I’m more interested in how fast can it move…
    dragonflies-like drones anyone?

    hope this gets further studying

  4. That’s a good concept but this implementation look fragile and doesn’t look like the material is going to last long..

    And did I read well?? 4000 V? This discard pretty much every application I thought off..

  5. Some places use a ‘.’ rather than a ‘,’ to mark thousands… It’s hard to say for sure what voltage there is. I assume if it was just 4 volts there wouldn’t be the need for 4 significant digits…

  6. Yes, it really is 4kV.

    It’s basically a capacitor, where the electrostatic pressure between plates causes physical deformation in the insulator in a predictable direction.

    They can be stacked and run in parallel to move some very heavy loads. They have a good power to weight ratio. They can move incredibly fast. And since it’s a capacitor, stored charge can even be partially recycled.

    A few years back I spent some time trying to imagine how you could DIY robot muscles with these. You’d need three things:

    1) Flexible electrodes. I did figure out a possible simplification here. Conductive graphite-loaded grease is available and cheap. It conforms and clings. While it has a relatively high resistance, it’s not such a big issue at these high voltages, and should work well; assuming of course the next item is not degraded by it…

    2) Very thin, defect free sheets of silicone or some other elastomer. The thinner the sheet, the more responsive the actuator is at lower voltage. But the thinner it is, the higher the possibility of any defect (like an air bubble) leading to an arc-through. I have some experience solvent thinning common silicone, and figured it might be possible to create a sheet composed of multiple very thin layers; doing it this way prevents any defect from going all the way through. Essentially the same technique used by tesla coil builders in making high-voltage caps with multiple layers of polyethylene. But I never got around to testing this, because you also need…

    3) A high-voltage driver capable of charging or discharging the actuator to any DC voltage from zero to 2-4kV. Good luck with that. :) Even if you can build one to experiment with, building several to make a real project like a robot arm/hand would be quite expensive, bulky, and possibly unsafe.

  7. Seems to me they could achieve the same by using tubes that are filled with pressurized air/gas.

    This does however confirm my theory that I need a team of 6 people to make my hacks for me, a team that has things like lasercutters :)

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