Wrinkle Characteristics Analysis of Human Skin with Age-Related Alteration of Mechanical Properties

Abstract

Human skin consists of epidermis, dermis and hypodermis, and their constitutions and mechanical properties are quite different. From the biomechanical standpoint, we have proposed a five-layered skin model and an aging model, where the elastic constants and thicknesses alter linearly with aging, and found that the specific buckling mode switches from the stratum corneum buckling to the epidermis buckling in the aging process. The buckling mode switch (BMS) causes a sudden enlargement of wrinkles and an increase of mechanical damages, and consequently leads to a rapid formation of permanent aged wrinkles. In this study, we used a three-layered skin model for further investigation on the validity of BMS, since the upper three layers were enough to investigate the BMS. We first clarified the buckling characteristics of multilayered structure and the mechanism of BMS, and next showed the occurrence point of BMS and its possibility through a parametric study on the specific buckling mode within the feasible range of the elastic constants and thicknesses. Moreover, we confirmed that our aging scenario with the BMS was consistent with the actual age-related changes in the material parameters, and found that the aging process of skin may cause the BMS.