The fibers can range from just a few micrometers in thickness to a few millimeters, and they can be hundreds of meters of long. You can weave other elements into the fiber, too, such as nanowires (as researchers did to measure tension), electrodes or optical fibers. A robotic limb wouldn't need external, bulky heat sources to activate the fibers. And if you bundle the fibers, they could provide automated, precise control.

While this is still a lab experiment, there's a lot of potential. Tiny medical robots could work on your body from the inside, while larger bots could be brawny, speedy or both. This could be particularly vital for prosthetic limbs, where hydraulics and other machinery can bog them down. An artificial limb could not only feel more natural, but offer a more comparable response time.