54. Biological Fibrillar Adhesives: Functional Principles and Biomimetic Applications

Specific mechanisms of adhesion found in nature are discussed in the chapter Bioadhesives (Chap.​ 53). One of the most discussed biological systems in the last decade is the so-called fibrillar adhesive of insects, spiders, and geckos. These systems are adapted for dynamic adhesion of animals during locomotion and, therefore, have some extraordinary properties, such as (1) directionality, (2) preload by shear, (3) quick detachment by peeling, (4) low dependence on the substrate chemistry, (5) reduced ability for contamination and self-cleaning, and (6) absence or strong reduction of self-adhesion. In the present chapter, we review on functional principles of such biological systems in various animal groups with an emphasis on insects and discuss their biomimetic potential. Data on ultrastructure and mechanics of materials of adhesive pad materials, movements during making and breaking contact, and the role that the fluid plays in the contact between pad and substrate are presented here. The main goal was to demonstrate how a comparative, experimental approach in studying biological systems aids in developing novel adhesive materials and systems. The micro-structured adhesive systems, inspired by studies of biological systems of insects, spiders, and geckos, are also shortly reviewed.