Citation link:
Publisher DOI: https://doi.org/10.1007/s00359-009-0457-0
https://media.suub.uni-bremen.de/handle/elib/5716
Publisher DOI: https://doi.org/10.1007/s00359-009-0457-0
Friction ridges in cockroach climbing pads: anisotropy of shear stress measured on transparent, microstructured substrates
Authors: | Clemente, Christofer J Dirks, Jan-Henning Barbero, David R Steiner, Ullrich Federle, Walter |
Abstract: | The contact of adhesive structures to rough surfaces has been difficult to investigate as rough surfaces are usually irregular and opaque. Here we use transparent, microstructured surfaces to investigate the performance of tarsal euplantulae in cockroaches (Nauphoeta cinerea). These pads are mainly used for generating pushing forces away from the body. Despite this biological function, shear stress (force per unit area) measurements in immobilized pads showed no significant difference between pushing and pulling on smooth surfaces and on 1-microm high microstructured substrates, where pads made full contact. In contrast, on 4-mum high microstructured substrates, where pads made contact only to the top of the microstructures, shear stress was maximal during a push. This specific direction dependence is explained by the interlocking of the microstructures with nanometre-sized "friction ridges" on the euplantulae. Scanning electron microscopy and atomic force microscopy revealed that these ridges are anisotropic, with steep slopes facing distally and shallow slopes proximally. The absence of a significant direction dependence on smooth and 1-microm high microstructured surfaces suggests the effect of interlocking is masked by the stronger influence of adhesion on friction, which acts equally in both directions. Our findings show that cockroach euplantulae generate friction using both interlocking and adhesion. |
Keywords: | adhesion; tribology; Biomechanics; direction dependence; lithography | Issue Date: | Sep-2009 | Publisher: | Springer | Journal/Edited collection: | Journal of comparative physiology / A | Issue: | 9 | Start page: | 805 | End page: | 814 | Volume: | 195 | Type: | Artikel/Aufsatz | ISSN: | 0340-7594 | Secondary publication: | no | Institution: | Hochschule Bremen | Faculty: | Hochschule Bremen - Fakultät 5: Natur und Technik |
Appears in Collections: | Bibliographie HS Bremen |
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