Gecko Adhesion as a Model System for Integrative Biology, Interdisciplinary Science, and Bioinspired Engineering: Video 5

A video from the 2014 review by Kellar Autumn, Peter Niewiarowski, and Jonathan B. Puthoff, "Gecko Adhesion as a Model System for Integrative Biology, Interdisciplinary Science, and Bioinspired Engineering," from the Annual Review of Ecology, Evolution, and Systematics.

Video 5 shows how gecko setae adhere when preloaded and dragged along the direction of curvature of the setae (this is in the same direction geckos use when they climb). In the lower left, the normal force (blue  line) is compressive initially during the load step, but immediately following the drag step, strong adhesion occurs (negative normal force) and the setae are drawn into tension. Notably, adhesion is sustained even as the setae slide across the substrate. The lower right plot illustrates frictional adhesion: Adhesion is coupled to friction, and the resultant force angle is approximately 30°. Adhesion is controlled by the shear force. During the pull step, shear force decreases, and adhesion returns to zero without the tacky behavior common to conventional adhesive tapes.