For a project, I need a transparent ball that is rigid, but under application of a voltage changes it's size, like a self-inflating balloon. Because it's rigid, however, and thus would break when expanded manually, I need to find a material that expands itself when the voltage is applied. I though about heating and about piezoelectric materials, but the changes are always too small, staying within a few milimeters of the original size. I've heard of electroactive polymers, but those aren't rigid. Shape memory polymers also seem to be an option, but I don't really know how well they work, and where to get them, etc. So, if anyone knows a material that can expand this way, or if someone finds a material that expands well enough when heated, please respond.

  • $\begingroup$ If all you need is the ball to shatter then consider electrical detonation of a small explosive charge. Or, electric release of a manually wound spring-loaded mallet. There's also shape memory alloy which you did not list, but frankly all the options you did list are exotic, cost a bundle and probably won't work. $\endgroup$
    – DKNguyen
    Dec 21 '20 at 23:31
  • $\begingroup$ No, exactly that's what I don't want to happen. It's a rigid ball that needs to change size without shattering. I'm sorry, maybe I worded that wrong in the question. $\endgroup$
    – Mat NX
    Dec 21 '20 at 23:46
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    $\begingroup$ You never defined how much movement you need other than "a few mm" is too small, but a few mm is MASSIVE for what is available. I do not believe the material you are searching for exists, let alone a transparent one. What is your budget anyways? Because anything of a size where you could casually call it a ball would costs many thousands if made out of piezoelectric materials. Make sure you're not chasing a pie in the sky idea. $\endgroup$
    – DKNguyen
    Dec 21 '20 at 23:48
  • $\begingroup$ No, yeah, I did realize that a piezoelectric materials wouldn't cut it, which is why I'm asking for other materials. I did experiment with dielectric polymers (As in electroactive polymer) for a bit, which were fairly promising, 2 domes that would both "buldge out", but unfortunately, they are elastic materials. $\endgroup$
    – Mat NX
    Dec 22 '20 at 0:06

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