A super-coiled polymer (cxSPA) actuator is an alluring idea. Instead of having a simple string being pulled by an electric motor, why not embed the actuation mechanism in the material itself? Just like animal muscles.

Making coaxial super-coiled polymer actuator (cxSPA) cheap and accessible

Of course, with almost no budget, I wouldn’t get far without thinking of how I could repurpose something affordable and accessible for a regular hacker on a budget. After all, these Coaxial Super-coiled Polymer Actuators (CoSPA) should be possible to make in a home lab setting.

Rough Plan

I plan on tweaking a 3D printer extruder a little bit by inserting a tiny syringe needle (or some centering mechanism) in the center of an extruder nozzle and feed a nichrome wire through it, with melted nylon flowing/extruding from around it throught the nozzle, pulling the wire with it and embedding it in the core of the newly extruded nylon fiber.

Mechanical/thermal property implications of remelting and drawing of nylon fiber

Twisting setup

DSC08511 DSC08504 DSC08500 DSC08495 DSC08493 DSC08484 DSC08483 DSC08481

Tests

IMG_20190322_100229 IMG_20190318_193056 IMG_20190318_193032 IMG_20190318_172618 VID_1 VID_2

VID_3

VID_4

VID_5

VID_6

VID_7