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Joule Heating Actuated Artificial Muscles

Using nickel plated nylon covered in hydrophilic graphene oxide it should be possible to finally make these work as intended.

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Using conductive additives and heat pipes I aim to make nylon artificial muscles usable in real world applications.

This is easier said than done, but I have got most of the failures out of the way and learned loads during the journey.

The challenge is to get a conductive elastomer to stick to nylon 6,6 artificial muscles and coat that with hydrophillic graphene oxide. The hyrdophillic layer will assist in wicking water up the muscles as they actuate and heat causing the water on them to evaporate. This will be accomplished by placing the muscles inside a 24 inch of mercury vacuum evacuated silicone tube. On the inside of the tube there will be a large surface area using macro morphology and hydrophobic pristine graphene nanoribbons. The silicone will have a very high loading of conductive silver, diamonds, and graphene to enable fast thermal transport. The exterior will also have a high surface area and use passive air cooling to remove heat from the muscles.

The difficulties are paramount, I have been at this for about 2 years now with very little luck. I have tried almost everything under the sun but am nearly there with graphene nano-ribbons, silver coated copper, and polyurethane. The trick is to make the coating conformal, consistent and very thin via- a dip coating process.

The main issue I will be having as I have always had is localized areas of high resistance that heat too quickly and destroy the muscle. Placing the muscles in the "heat pipe" should help alleviate some of this issue.

The biggest issue I have had is funding, I have slowly been trying every conductive paint/glue I can get my hands on and have determined I have to make my own.

The next issue is the cost of platinum cure silicone, industrialdiamonds, CNT, graphene, and silver but if I can snag some of that research money I should finish much faster as I can make iterations without having to eat just beans and rice (the flatulence gets old.)

This documentation describes Open Hardware and is licensed under the CERN OHL v. 1.2. You may redistribute and modify this documentation under the terms of the CERN OHL v.1.2. (http://ohwr.org/cernohl). This documentation is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN OHL v.1.2 for applicable conditions

  • 1 × Precipitated Silver Powder
  • 1 × 300 Mesh Copper Powder
  • 1 × 300 Mesh Nickel Powder
  • 1 × Polyurethane
  • 1 × Nickel Acetate Solution for electroplating

View all 15 components

  • New Plating Setup Does the Job in Minutes

    MECHANICUS05/07/2016 at 03:13 0 comments

    You can see the copper creeping around the coil, it is the white colored stuff over the black.

    This setup takes about 20 minutes to completely plate a muscle, whereas it took days before.

    The electrolyte is copper sulfate and h2so4 with a copper pipe that the muscles are wrapped around to stretch them out allowing plating between coils. The copper pipe goes to the negative terminal.

    The positive terminal is just some copper foil.

    The 8-track player box was repurposed to house my 3d printed stir plate contraption thingy.

    A stir bar was made using a piece of ptfe tubing a neodymium magnet and some silicone.

    The voltage reads zero for some reason but current set to 100 mA and voltage set to .9 volts before hooking it up works the best.

  • The difficulties are immense with this one.

    MECHANICUS03/22/2016 at 00:13 0 comments

    The graveyard of failed muscles grows daily.

    What I have learned is that sanding the line before twisting with 400 or 600 grit sandpaper vastly improves the adhesion and toughness of the conductive coating.

    Silver may not be necessary Nickel powder seems to have the same resistance when used with a polyurethane binder.

    Graphene sucks and is highly overrated it generally is much to resistive to be used in this application.

    Homochiral and heterochiral twists are pretty much uncontrollable with this 150lb test, I may have to switch back to the 80lb test for the prosthetic hand as it seems to work so much better.

    A different twist morphology can give less power but longer actuation distance and may be the way to go for a prosthetic hand. I discovered this by accident as twisting these things only goes correct about 75% percent of the time and the other 25% you get side coils. However these side coils can be made on purpose and when given a quaternary twist pattern actually have a longer retraction distance and can be made conductive much more easily as there is more surface area.

    I will be focusing on anything goes for the 2016 HAD prize for this small project as I am 99% of the way there. I also need this to work very well for the final HAD prize segment of assistive technologies.

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Zach Smith wrote 04/27/2016 at 00:57 point

I VERY briefly looked into this. I thought of putting a single very thin conductor inside extruded acrylic and coiling it. The conductor would be made of Kanthal A1 wire. I stopped working on it because I couldn't find a supplier that sold resin pellets for extruded acrylic with a high enough thermal expansion coefficient.

Aside from using paraffin wax extruded acrylics boast a very high thermal expansion coefficient which allows for a highly efficient artificial muscle. After getting a few coils to work in parallel for combined strength a means of quickly cooling the muscle would be required.

The chase scene in the movie "I-Robot" comes to mind where Detective Spooner (Will Smith) shoots Sonny. You see a blue liquid leaking from the gunshot wound. I imagine this would be the "coolant" as it were.

P.S. I may be interested in teaming up. XD

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MECHANICUS wrote 04/27/2016 at 04:23 point

Thanks for the comment, I have been pulling my hair out over this for almost 2 years now. I tried everything from extruding nylon 6/6 with carbon nanotubes to 100 dollar a bottle copper/silver paint. 

I think I have it figured out now with copper plating of a graphite coating, then graphene oxide hydrophilic coating on top of that.

Then the whole thing goes into a diamond, graphene oxide nanoribbon silicone composite sleeve that has reduced atmospheric pressure and a hydrophobic coating on the inside.  The coolant liquid will be a graphene oxide water suspension. This will function like a CPU heat pipe. 

I have the chemistry and mechanics of it all worked out, however, I could definitely use some help on the EE and computer programming side of things. I just got an arseduino in yesterday and my relay board in today.

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zaalexander wrote 12/11/2015 at 13:23 point

Cool! I remember reading about this a couple of years ago when the research first came out. I'm excited to see what you come up with.

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MECHANICUS wrote 12/11/2015 at 13:30 point

Yes I have been smashing my head against a brick wall for over a year on this trying all sorts of stuff like extruding nylon 6/6 with carbon nanotubes, ferro fluids, etc.

I think I have it finally figured out and its fairly simple.

  Are you sure? yes | no

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