Gecko setae

Gecko setae stick more strongly the faster they slide. This is because friction between dry, hard, macroscopic materials typically decreases at the onset of sliding, and as velocity increases, friction continues to decrease because of a reduction in the number of interfacial contacts, due in part to wear. Gecko setae did not exhibit the decrease in adhesion or friction characteristic of a transition from static to kinetic contact mechanics. Instead, friction and adhesion forces increased at the onset of sliding and continued to increase with shear speed from 500 nm/s to 158 mm/s.

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(Rate-dependent frictional adhesion in natural and synthetic gecko setae, by Gravish et al)