Tribological properties of femur–tibia articulation of lubber grasshopper

This study focuses on the tribological properties of femur–tibia articulation of grasshopper (Romalea guttata) leg joints. It was found that the coefficient of friction for the articulation was very low, 0.052±0.001 and 0.037±0.002 under dry and squalane lubricated conditions, respectively. A synergistic combination of a unique joint morphology and internal nanostructure of grasshopper joints were found to be responsible for their exceptional frictional and mechanical properties. Overall, given the exact mechanism by which insect joints reduce friction and wear is still unknown, this original study reveals the main characteristics of the insect joints responsible for their efficient operation and improved tribological properties.

► This work is the first to study the tribological properties of insect leg joints. ► The friction coefficient was very low under dry and squalane lubricated conditions. ► The mechanical properties were superior to most natural articulations. ► Internal and surface nanostructures play important roles in tribological behavior.