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Future Robotic Muscles Could Be Made of Nylon

MIT researchers have figured out that by selectively heating parts of nylon fibers, they make fine-tuned movements.

Oftentimes engineers take cues from nature for inspiration. The researchers at MIT creating nylon muscles are one such example of that.

This video by MIT's Melanie Gonick, describes how artificial muscles—used in robotics, aviation, and automobile industries—mimic the intricacies of real muscles. However, these artificial muscles can also be expensive and limited in their capabilities.

In looking for a material that can reproduce the bending motions that natural muscles do regularly, MIT researchers, have found a solution in nylon fiber. When nylon, like some other polymer fibers, is heated, it shrinks in length, but expands in diameter. "The cooling rate can be a limiting factor," said doctoral candidate Sayed Mirvakili. "But I realized it could be used to an advantage." Therein lies the idea of heating only a certain side of the fiber, so that only one side contracts faster than heat can get through the other side, hence causing a bending motion.

They found that when modifying the shape of the fiber and heating it selectively on one side can force it to bend. And by heating certain areas of the fiber in a sequence, they found they could get it to perform more complex movements.

For example, the researchers used this technique to make the fibers move in circles and figure eight motions, or a circular pattern and lissajous pattern. Various heat sources were used on the fibers to achieve this, including chemical reaction heatings, electrical resistance heating, and laser beams that shine on the filament.

Using this technique, the researchers say the heating up nylon fiber can be used to make various biomedical devices, including robotic grippers and machine components. "These new bending actuators could have immediate application," said professor at Australia's University of Wollongong Geoffrey Spinks.

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