PerspectiveMaterials Science

Fibers Do the Twist

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Science  21 Feb 2014:
Vol. 343, Issue 6173, pp. 845-846
DOI: 10.1126/science.1250471

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Summary

In a rubber band–powered airplane, a pretwisted band untwists when the hook used to initially balance its torque is released (see the figure). Such an actuation is based on the elastic recovery of the stretched polymer chains. The material has to be mechanically retwisted to operate but the method is simple and efficient, because the rubber band delivers almost as much energy as needed to twist it. Unfortunately, soft rubber cannot easily provide large stress and cannot be used in modern applications such as robotics, artificial muscles, smart textiles, and new medical devices. But as Haines et al. show on page 868 of this issue (1), the concept of twisted fibers can nevertheless be useful in demanding actuator applications.