Tribological properties of sandfish skink's scale under micro loads - Observation of micro structure and tribological properties under μnload

Sandfish (Scincus scincus), which is kind of reptile living in desert, can move in sand like swimming. It is thought that since sandfish has a low friction scales, it is able to do that. However, the mechanism of the low friction property of the scales is not yet known. In this study, a micro structure of sandfish's scales was investigated, and their tribological properties under (IN loads were measured. Cuticle-like structure, which is observed on human hairs, appeared on the scales. Detected elements on the scales were O, C, N, and S. Ca and Si, which are elements of hard shells and bones, were not detected. A contact angle of sandfish's scale was around 90°, and polytetrafluoroethylene (PTFE) and polyimide (PI) had contact angles of approximately 110° and 60°, respectively. However, an adhesion force of sandfish's scales was lower than those of PTFE and PI. With the exception of a few frictional conditions, a friction force of sandfish's scales was lower than those of PTFE and PI, which would result from the low adhesion force of sandfish's scales.