Harvard University Division of Engineering and Applied Sciences Kavli Institute School of Engineering and Applied Sciences Department of Organismic and Evolutionary Biology Harvard University
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    Biomimetic Ratchets

    The creeping, crawling, and slithering gaits of worms, snails, and snakes show how organisms are able to adapt to and exploit certain environmental and ecological niches. Because these gaits involve the continuous interaction of long flexible bodies with a solid substrate, they are qualitatively different from the more commonly studied modes of animal locomotion such as walking, swimming, and flying (1). In these gaits, periodic pulses of muscular defor mation are rectified by one or more symmetry-breaking mechanisms, just as in a mechanical ratchet. Inspired by these locomotory behaviors, we study the motion of a lubricated rod of a hydrogel on a soft substrate. We show that it is possible to mimic observed biological gaits by vibrating the substrate and by using a variety of mechanisms to break longitudinal and lateral symmetry. Our simple theory and experiments provide a unified view of the creeping, undulating, and inchworming gaits observed in limbless locomotion on land, all of which originate as symmetry-breaking bifurcations of a simple base state associated with periodic longitudinal oscillations of a slender gel.

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   Last Updated: January 31, 2018

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January 31, 2018