Soft Robots: Making Robot Air Muscles

Picture of Soft Robots: Making Robot Air Muscles
Pneumatic robot air muscles can be easily made using Oogoo. These flexible, silicone artificial muscles have the advantage that they are inexpensive and can be easily molded to fit almost any robot body.

The intro pic shows a six segment elbow muscle, a three segment actuator muscle, and a single segment muscle under low air pressure. The thumb pic shows the artificial muscles with no pressure.

You can see a robot arm and gripper that was made using this type of artificial muscle, here:
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Step 1: How artificial robot muscles Work

Picture of How artificial robot muscles Work
These artificial robot muscles are made by laminating thin layers of Oogoo which is a silicone rubber that can be cast in any thickness. For info on Oogoo see here:

An artificial muscle segment is cast in two layers with a thin piece of plastic between the layers to allow for air expansion. This creates a simple air bladder that can glued together in many segments with spacers to create curving or straight robot muscles.

The step one pic shows a 3d illustration of a six segment silicone robot muscle. Ideally, an artificial robot muscle like this could be directly printed in one piece. I have not found a 3d printer service that can print silicone or rubber at an affordable price. So, for now, I can only do the illustration and must use hand techniques to create the muscles. I am looking into the 3d printing of plastic molds that could be used to cast the Oogoo robot muscles in one step.

123D was used to create the illustration.

Step 2: Materials

Picture of Materials
The step 2 pic shows the pieces that were cast to make the six segment robot muscle.

Corn starch
100% silicone caulk
plastic cups
plastic bag

1/16" thick plastic sheet. I used phenolic sheet that I had, but polycarbonate, acrylic or any other plastic sheet material could be used.

6"x6" plywood

Spray Lacquer from hardware store.

12 volt air/vacuum pump from:

12 volt solenoid air valves from:

Aquarium air hose from:

Raintree drip irrigation fittings from
jlyvers7431 year ago
A very clear instructable and an awesome idea! My mind is in overdrive thinking of the many possible applications of your muscles!
Awesome, I love this! On step 3 you could use a 2" hole saw and cut all six segments in the plastic so you could screed an entire muscle in one shot.
danzo3211 year ago
This is wonderful. Would it help if each muscle segment was more the shape of an orange segment? I think I could rotocast silicone rubber.
mikey77 (author)  danzo3211 year ago
I have only tried a dozen different shapes for Oogoo air muscles. I have by no means found the optimum configuration. I suspect there could be several hundred useful forms of silicone air muscles. Lots of room for experimentation.

Roto-casting the Oogoo is a good Idea. It could make for some unique hollow shapes. I think some commercial silicone bellows are made that way.

Have you roto-casted before? I would be interested in trying it.
roliop2 years ago
Another neat Oogoo app !

You mention glueing the air-hose to the muscle: does Oogoo stick to the hose, or did you find another glue ?


mikey77 (author)  roliop2 years ago
Oogoo glues extremely well to set up Oogoo and to some kinds of silicone hose. The 1/8" hose I used that worked best is very supple and almost sticky to the touch.

Unfortunately, the less expensive, smooth and stiffer, silicone hose that they sell for aquariums does not glue well enough to easily hold air pressure.
old.bodger2 years ago
Could you give any details of the air valves - manufacturer - source etc? I've been trying to find some with no success. Thanks
Now I read it carefully and see that you have! Thanks Sorry!
I will try to mow an raise version. Don't ask me how.
WWC2 years ago
Very cleaver. If you said what the green " hinged " pieces were i could not find. What are those?
mikey77 (author)  WWC2 years ago
I have updated the step 1 pic and added to the step 4 explanation.
I hope that helps.
WWC mikey772 years ago
It does. Thank You very much!
agis682 years ago
that is really genious!
fjalex2 years ago

anyone have a video of this instructable?

I got excited over this! Thanks for sharing! Muhahahaha!
micraman2 years ago
That is AWESOME! I really need to perfect my oogoo mixing!
drkocher2 years ago
Thats a realy great and easy way to make your own air muscle.

Look at the following links. These guys make quite nice soft 3d printed Robots.
caitlinsdad2 years ago
Interesting, never thought that bladders are cast in one piece. Reminds me of the replicant detector machine in Blade Runner.
ehudwill2 years ago
Great idea. Thanks for sharing.