The principle of contact splitting is mainly used to explain the impressive capabilities of geckos, spiders and some insects to adhere to and to run on walls and ceilings. Those animals have instead of a large continuous contact hundreds to billions of tiny hairs called setae under their feet. Those micro- and nano-structured setae can form intimate contact with the substrate. Based on these findings, many attempts to mimic such adhesive systems were made and a new class of adhesives has emerged: bio-inspired microstructured adhesives. Although some convincing examples have shown their usefulness in some real life applications, a reliable alternative to conventional bonding strategies is still lacking. However, our recent works on the hairy adhesive systems in insects have revealed two important features within individual setae which allow for robust and reliable reversible adhesion: (1) the presence of a material gradient along the setae leads to an enhanced adaptability to rough surfaces and prevents clusterization of setae and (2) the presence of joint-like elements within setae further enhances the adaptability and allows for robust adhesion. |