Mechanics of robust and releasable adhesion in biology: Bottom–up designed hierarchical structures of gecko

Gecko and many insects have evolved specialized adhesive tissues with bottom–up designed (from nanoscale and up) hierarchical structures that allow them to maneuver on vertical walls and ceilings. The adhesion mechanisms of gecko must be robust enough to function on unknown rough surfaces and also easily releasable upon animal movement. How does nature design such macroscopic sized robust and releasable adhesion devices? How can an adhesion...