Low-cost artificial muscle fibre fishes for applications

Fibre such as this could have applications in robotics, prosthetics or even in clothing that automatically adjusts to fit.

Nylon artificial muscle fibres appear to have a property that has so far eluded other artificial muscle fibres: they can reproduce the bending motion of fingers and limbs. Moreover, the fibre can do this alone, with no need for extra mechanical pulleys or wheels.

The key to the properties is the way the fibre is shaped and heated. In a paper in the journal Advanced Materials, Prof Ian Hunter and Seyed Mirvakili, a PhD student, describe how they found and developed the specific properties of nylon fibre. Previously, artificial muscle fibre research had used nylon in twisted and coiled filaments to mimic the basic linear activity of muscles; contracting and expanding in a straight line. The systems could not bend, however. Fibres capable of reproducing bending motion tend to use "exotic materials to do the job, and they are very difficult and very expensive to make," Mirvakili said. These materials include carbon nanotubes fibres, which are too expensive for widespread use, and shape memory alloys, which break after relatively few expansion-contraction cycles.