From robotics to prosthetics, creating materials that mimic the actions of human muscle tissue are in great demand. Researchers at the University of Texas at Dallas have developed a technology that creates threads that can contract on demand, which could open the door to a wide range of applications.

The technique involves twisting fibers into tight coils. The researchers have tried a range of materials, from carbon fiber to ordinary nylon thread and plastic fishing line. The result is a material that works like an “over-twisted rubber band.” By heating the threads, they contract. When cooled, they relax and return to their original length. This approach turns out to be quite powerful; fishing line “muscles” can lift 100 times more weight than human skeletal muscle of the same length and weight. By arranging these fibers into spirals, they can lie flat when contracted, which increases the amount by which they can shrink when activated.

These fibers could be woven into textiles that can expand and contract as needed. They have been demonstrated to work in normal sewing machines and weaving looms. The technology could be used not just to provide actuators for robots and powered prosthetic limbs, but could also be incorporated into “smart” clothing that could augment the wearer’s strength.