Advances in the contact mechanics theory and applications of biomimetic artificial adhesives inspired by biological multiscale hierarchical structures

Living organisms, such as geckos and insects, exhibit excellent climbing ability on various complex surfaces due to the hair-like hierarchical adhesive systems of their attachment devices. Over the past few decades, an increased understanding of the mechanisms of multiscale hierarchical adhesion systems and the continual improvement of theoretical modeling have promoted the rapid advancement in the design and application of biomimetic artificial adhesives. The modeling of biomimetic artificial adhesives has been developed from simple structures to complex constructions with multilevel hierarchical properties. A review of advances in developing these contact mechanics models is presented here. Adhesion and friction models considering multiscale hierarchical structural forms are discussed, focusing on multiscale hierarchical models based on the development of the Cantor-Borodich profiles. Finally, the most recent developments in studies of artificial setae having spatula-like ends, both axisymmetric and non-axisymmetric, are reviewed.