Abstract
Geckos can cling to almost any surface using dense arrays of microscopic hierarchical hairs called setae. The flat, regular, terminal branches of the setae adhere by the van der Waals dispersion force, and the mechanics of the gecko attachment scheme are a current topic among biologists and researchers in smart materials for adhesion. We studied the friction behavior of natural gecko arrays. Our experiments demonstrate the presence of velocity strengthening dynamic friction over the range of velocities from 5×10−4 to 158 mm/s and a range of specimen elastic moduli from 1.1 to 3.6 GPa. From these dynamic experiments, we calculate low-v activation volumes between 1500 and 3000 nm3. Since these volumes are 3 orders of magnitude larger then are typical for bulk materials, we conclude that there is weak coupling between individual sliding contacts in the gecko system.
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Acknowledgments
This work was supported by the United States National Science Foundation under awards NBM 0900723 and IOS 0847953.
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Puthoff, J.B., Holbrook, M., Wilkinson, M.J. et al. Probing Friction Forces Using Gecko Materials. MRS Online Proceedings Library 1465, 39–43 (2012). https://doi.org/10.1557/opl.2012.1047
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DOI: https://doi.org/10.1557/opl.2012.1047