Mechanisms of Adhesion in GeckosΡΡΠ°ΡΡΡ ΠΈΠ· ΠΆΡΡΠ½Π°Π»Π°
ΠΠ½Π½ΠΎΡΠ°ΡΠΈΡ: The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (π) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (WGS) is in fact proportional to \(\sqrt{(1\ {+}\ cos{\theta})}\) β , and only for π > 60Β°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 ΞΌm displacement yielded a very large adhesive force of 200 microNewton (ΞΌN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30Β° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.
ΠΠΎΠ΄ ΠΈΠ·Π΄Π°Π½ΠΈΡ: 2002
ΠΠ²ΡΠΎΡΡ: Kellar Autumn
ΠΠ·Π΄Π°ΡΠ΅Π»ΡΡΡΠ²ΠΎ: Oxford University Press
ΠΡΡΠΎΡΠ½ΠΈΠΊ: Integrative and Comparative Biology
ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ»ΠΎΠ²Π°: Adhesion, Friction, and Surface Interactions, Force Microscopy Techniques and Applications, Insect and Arachnid Ecology and Behavior
ΠΡΡΠ³ΠΈΠ΅ ΡΡΡΠ»ΠΊΠΈ: Integrative and Comparative Biology (PDF)
Integrative and Comparative Biology (HTML)
CiteSeer X (The Pennsylvania State University) (PDF)
CiteSeer X (The Pennsylvania State University) (HTML)
PubMed (HTML)
Integrative and Comparative Biology (HTML)
CiteSeer X (The Pennsylvania State University) (PDF)
CiteSeer X (The Pennsylvania State University) (HTML)
PubMed (HTML)
ΠΡΠΊΡΡΡΡΠΉ Π΄ΠΎΡΡΡΠΏ: bronze
Π’ΠΎΠΌ: 42
ΠΡΠΏΡΡΠΊ: 6
Π‘ΡΡΠ°Π½ΠΈΡΡ: 1081β1090