Contribution of stratum corneum in determining bio-tribological properties of the human skin

The present study deals with the impact of stratum corneum (SC) on the human skin bio-tribological properties. First, the nano-indentation and nano-friction tests were realised ex vivo onto isolated SC. The results showed that isolated SC behaved as a gradient material in the deepest direction. Furthermore, we demonstrated that the mechanical properties of SC differ markedly from those of whole skin. The in vivo tribological tests were realised with an original tribometer (indentation and friction), specially developed for the soft materials. These results were confirmed in vivo by the removal of SC from human skin (by successive tape-stripping), which showed principally an increase of the adhesion force between the probe and the skin surface and a decrease of the lateral stiffness in absence of SC. In conclusion, we showed that SC comprises a friction adhesion component which influences the overall frictional skin behaviour.