Building Pneumatic Actuators With 3D Printed Molds

Pneumatic actuators offer interesting perspectives in applications like soft robotics and interaction design. [Aidan Leitch] makes his own pneumatic actuators from silicone rubber. His actuators contain embedded air channels that can be filled with pressurized air and completely collapse to a flat sheet when no pressure is applied.

pneumatic-actuators-animationThe process is based on the research work of Kevin C. Galloway et al. on “Zero Volume Air Chambers”. The team found that they could pour a thin layer of silicone rubber into a flat mold, then selectively apply a pattern of mold release to the surface of the cured layer using a laser-cut mask, and then pour a second layer of silicone on top. The mold release prevents the two layers of silicone from bonding together, leaving inflatable air channels behind that require close to zero volume when unpressurized.

To replicate their results, [Aidan’s] wrote an OpenSCAD script that generates 3D printable molds from black and white images. The molds include the mask for the release agent, whereas white regions in the image define the embedded air channels and black regions define solid silicone. Enjoy the video below where [Aidan] demonstrates his process!

Thanks to [Jean] for the tip!

11 thoughts on “Building Pneumatic Actuators With 3D Printed Molds

  1. Cool technique. With a little research into/ quantization of how the level thickness,shape, and material properties/parameters affects its end properties and this could be extremely useful.

    1. You can design a set of those parts and use Boolean operations in OpenSCAD to combine them to whatever inflatothing you are currently working on. No that is not a word, I made it up, would you rater bubbleoid?

  2. It’s worth noting other papers by Kevin Galloway et al shown how by embedding/attaching other materials to the silicone you can significantly change their performance. I was especially intrigued by one actuator that had aramid fibers embedded on one side. This meant that side was effectively restrained and the actuator curved about it. Presumably you could combine the expansion pneumatics shown here and something that contracts like the VAMP and create something with some antagonism and the ability hold a pose with more accuracy?

  3. Genius .. I have used “lithography-like” techniques for fabrication before, but never made the connection that I was using lithography. Now I have a whole new fabrication “vocabulary” at my disposal.

    This kind of thing is exactly why I read Hackaday regularly. Thanks!

  4. this could make for some interesting interface choices, perhaps placing a tactile button switch under it (discourages pressing the button while inflated) or hooking up a sip/puff switch to the air channel(s) and selectively inflating them to present contextual choices to press.

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