Microtribology of biological materials

This paper presents a study on friction and indentation of attachment pads of the great green bush cricket, using a system involving a biological mate rial and a flat surface. The pads are evolutionarily optimized frictional d evices that are adapted to attach the insect to a variety of natural surfac es. The attachment pads of both living and dead insects were tested and eva luated using several analysis techniques. These techniques included frictio n analysis by microtribometry, microindentation, scanning electron microsco py (SEM), histologic sectioning, and shock freezing. Microtribological anal ysis showed that the friction between pad and surface is anisotropic. The a nisotropy increases with increasing normal force. Microindentation revealed that the pads respond very flexibly to applied loads leading to an optimiz ed morphology with respect to contact area. All results make clear that the microtribological properties are a perfect combination of surface structur e, lubrication and active interface control.