Friction in nature

Nature has found a number of ways to efficiently tackle friction problems. It has solutions to provide ultra low friction in the case of lubricated systems, ultra high friction in the case of adhesives or in some cases even controlled adaptable friction performance. Frictional surfaces can be found on different scales in nature from a nanometre scale to a macro scale. From a wide variety of natural systems synovial joints have probably attracted more research attention than other systems and this is fully justified as they are examples of ideal synergy between lubrication process and materials technology. Other examples include shark skin riblets for drag reduction, hierarchical structures for maximum adhesion or mucus and slime for an improved slip. In this contribution a summary of natural frictional systems is presented. Several examples of the successful use of biomimicry for the manipulation of the interface to provide the desired functions are presented here. Finally directions of further exploitation of a biomimetic approach in tribology are discussed.