Biological adhesion for locomotion: basic principles

Surface roughness is the main reason why macroscopic solids usually do not adhere to each other with any measurable strength; even a root-mean-square roughness amplitude of approx. 1 μm is enough to completely remove the adhesion between normal rubber (with an elastic modulus E ≈ 1 MPa) and a hard nominally flat substrate. Strong adhesion between solids with rough surfaces is only possible if at least one of the solids is elastically very soft. Biological adhesive systems used by insects, tree frogs and some lizards for locomotion are built from a relatively stiff material (keratin-like protein with E ≈ 1 GPa). Nevertheless, strong adhesion is possible even to very rough substrate surfaces by using non-compact solid structures consisting of thin fibers, plates and walls. In order to optimize the bonding to rough surfaces while simultaneously avoiding elastic instabilities, e.g., lateral bundling (or clumping) of fibers, Nature uses a hierarchical building principle, where the thickness of the fibers (or walls) decreases as one approaches the outer surface of the attachment pad. Some lizards and spiders are able to utilize dry adhesion to move on rough vertical surfaces, which is possible due to the very compliant surface layers on their attachment pads. Flies, bugs, grasshoppers and tree frogs have less compliant pad surface layers, and in these cases adhesion to rough surfaces is only possible because the animals inject a wetting liquid in the pad-substrate contact area, which generates a relative long-range attractive interaction due to the formation of capillary bridges.

[1]  K. Kendall,et al.  Surface energy and the contact of elastic solids , 1971, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[2]  David Tabor,et al.  The effect of surface roughness on the adhesion of elastic solids , 1975, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[3]  K. Johnson.  Contact Mechanics: Frontmatter , 1985 .

[4]  H. W. Levi,et al.  Systematics and Evolution of Spiders (Araneae) , 1991 .

[5]  P. Gennes,et al.  Dewetting of a water film between a solid and a rubber , 1994 .

[6]  Robert N. Fisher,et al.  A comparative analysis of clinging ability among pad‐bearing lizards , 1996 .

[7]  J. Shea,et al.  Sliding Friction-Physical Principles and Applications , 1998, IEEE Electrical Insulation Magazine.

[8]  Stanislav N. Gorb,et al.  The design of the fly adhesive pad: distal tenent setae are adapted to the delivery of an adhesive secretion , 1998, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[9]  F. Brochard-Wyart,et al.  Dewetting at Soft Interfaces , 1998 .

[10]  J. Barbera,et al.  Contact mechanics , 1999 .

[11]  B. Persson.  Theory of rubber friction and contact mechanics , 2001 .

[12]  M. Scherge,et al.  Biological micro- and nanotribology , 2001 .

[13]  F. Brochard-Wyart,et al.  Dewetting Nucleation Centers at Soft Interfaces , 2001 .

[14]  Stanislav N. Gorb,et al.  Ultrastructure of attachment specializations of hexapods (Arthropoda): evolutionary patterns inferred from a revised ordinal phylogeny , 2001 .

[15]  S. Gorb.  Attachment Devices of Insect Cuticle , 2001, Springer Netherlands.

[16]  R. Full,et al.  Evidence for van der Waals adhesion in gecko setae , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[17]  B. Persson,et al.  Adhesion between an elastic body and a randomly rough hard surface , 2002, The European physical journal. E, Soft matter.

[18]  U. Schwarz,et al.  Chemical composition of the attachment pad secretion of the locust Locusta migratoria. , 2002, Insect biochemistry and molecular biology.

[19]  Stanislav N. Gorb,et al.  The effect of surface roughness on the adhesion of elastic plates with application to biological systems , 2003 .

[20]  A. Volokitin,et al.  Role of the external pressure on the dewetting of soft interfaces , 2003, The European physical journal. E, Soft matter.

[21]  S. Gorb,et al.  From micro to nano contacts in biological attachment devices , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[22]  Bo N. J. Persson,et al.  On the mechanism of adhesion in biological systems , 2003 .

[23]  Zum Haftproblem der Gecko-Füsse , 1967, Naturwissenschaften.

[24]  B. Persson,et al.  Dewetting at soft viscoelastic interfaces. , 2004, The Journal of chemical physics.

[25]  Bo N. J. Persson,et al.  Squeeze-out and wear: Fundamental principles and applications , 2004 .

[26]  B N J Persson,et al.  Contact area between a viscoelastic solid and a hard, randomly rough, substrate. , 2004, The Journal of chemical physics.

[27]  K. Shull,et al.  Deformation behavior of thin, compliant layers under tensile loading conditions , 2004 .

[28]  S. Gorb,et al.  Evolution of locomotory attachment pads in the Dermaptera (Insecta). , 2004, Arthropod structure & development.

[29]  Giuseppe Carbone,et al.  Adhesion between a thin elastic plate and a hard randomly rough substrate , 2004 .

[30]  B N J Persson,et al.  The effect of surface roughness on the adhesion of solid surfaces for systems with and without liquid lubricant. , 2004, The Journal of chemical physics.

[31]  Ralph Spolenak,et al.  Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurements. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[32]  B. Persson,et al.  Crack propagation in rubber-like materials , 2005 .

[33]  K. Autumn,et al.  Evidence for self-cleaning in gecko setae. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[34]  B. Persson,et al.  Crack propagation in viscoelastic solids. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[35]  R S Fearing,et al.  High friction from a stiff polymer using microfiber arrays. , 2006, Physical review letters.

[36]  Frédéric Caupin,et al.  Cavitation in water: a review , 2006 .

[37]  Huajian Gao,et al.  Mechanics of robust and releasable adhesion in biology: bottom-up designed hierarchical structures of gecko. , 2006 .

[38]  Yu Tian,et al.  Adhesion and friction in gecko toe attachment and detachment , 2006, Proceedings of the National Academy of Sciences.

[39]  W. Barnes,et al.  Wet but not slippery: boundary friction in tree frog adhesive toe pads , 2006, Journal of The Royal Society Interface.

[40]  W. Briscoe,et al.  Boundary lubrication under water , 2006, Nature.

[41]  Walter Federle,et al.  Why are so many adhesive pads hairy? , 2006, Journal of Experimental Biology.

[42]  B. Persson.  Contact mechanics for randomly rough surfaces , 2006, cond-mat/0603807.

[43]  Heinz Schwarz,et al.  Material structure, stiffness, and adhesion: why attachment pads of the grasshopper (Tettigonia viridissima) adhere more strongly than those of the locust (Locusta migratoria) (Insecta: Orthoptera) , 2006, Journal of Comparative Physiology A.

[44]  B. Persson,et al.  Biological Adhesion for Locomotion on Rough Surfaces: Basic Principles and A Theorist’s View , 2007 .

[45]  Bharat Bhushan,et al.  Adhesion analysis of multi-level hierarchical attachment system contacting with a rough surface , 2007 .