Friction, adhesion and durability and influence of humidity on adhesion and surface charging of skin and various skin creams using atomic force microscopy

Abstract

Skin cream is commonly used to improve skin health and create a smooth, soft and moist perception by altering the surface roughness, friction, adhesion, elasticity and surface charging of skin surface. In this study, we present the first systematic study on friction, adhesion, durability and influence of humidity on adhesion and surface charging of skin and various skin creams using atomic force microscopy. Skin is subjected to various daily activities with time, and the durability is closely tied to product compositions. Durability of various skin creams was studied by repeated cycling tests. In order to better understand the frictional behaviour, the dynamic viscosities of various skin creams were measured. Skin cream thinly coats the skin surface and can cause drastic changes in the mechanical properties. In addition to mechanical properties, adhesive force is one of the important factors in determining the tactile perception of skin cream and is directly affected by the film thickness. Because the environmental dependence of skin and skin cream is of importance, the influence of humidity on adhesive force, film thickness and Young's modulus mapping were measured using force distance technique. The health and feel of skin are significantly affected by its surface charging, the surface potential of skin and various cream-treated skins was measured using the Kelvin probe method.