Mushroom-shaped geometry of contact elements in biological adhesive systems

It is well known that geometry of contact element is an extremely important factor affecting adhesion. Comparing various biological adhesive systems, we find that mushroom-shaped geometry of contact elements is widely spread in nature. Based on experimental data obtained with an artificial model system implementing a mushroom-shaped geometry of contact element, we discuss the principles responsible for particularly strong adhesion in this type of contact. Finally, we draw a general relationship between functional types of different biological adhesive systems and geometry of contact elements.