MIT Engineers Develop Nylon Fibres Used To Make Artificial Muscle

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MIT Engineers Develop Nylon Fibres Used To Make Artificial Muscle

MIT mechanical engineers have developed an easy and cheap method of creating artificial muscle fibres. In the new study, published in the journal Advanced Materials, the scientists used nylon fibre to replicate natural muscle fibres. Artificial muscles are materials or devices that contract & expand in response to an external stimulus like voltage, pressure or temperature.

Researchers have previously shown that artificial muscles could extend and retract further than normal muscles. Artificial muscles are an emerging technology that have many uses from biomedical robotics to the aviation and automobile industries.

Nylon is cheap and easily accessible, and scientists have previously used twisted coils of nylon to create artificial fibres. The advancement of the new study lies in the ability of the nylon to reproduce the bending motions of muscle fibres.

When heated, fibres shrink in length but increase in diameter. To turn that quality into a bending motion would previously have required a pulley and other extraneous mechanical parts. But the new study uses nylon heating to their advantage. The team figured out that they could produce a bending motion by using voltage to heat one side of the fibre.

They began by modifying the cross-section of nylon fishing line fibres, changing its shape from round to square. Then they tried controlling from which direction they heated the fibre. Depending on the direction, one side would begin contracting before the heat could reach the other side, producing a bending motion. They were able to make more complex motions with the fibres, including figure eights and circles.

"The cooling rate can be a limiting factor. But I realised it could be used to an advantage," Seyed Mirvakili, a Ph.D. student at MIT and the lead on the study, said in a press release.

In the past, scientists have used materials that were very expensive and very difficult to make.

The materials should also be long-lasting and able to go through many contraction cycles. Researchers have tried to use carbon nanotubes, which are incredibly long-lasting but are very expensive. Others have tried using shape-memory alloys which do not last very long. Nylon is both long-lasting and can expand and contract quickly.

According to Ian Hunter, a mechanical engineering professor at MIT, the fibres might be used to make self adjusting shoes that tighten when you put them on or change in shape and stiffness as you walk.