%0 Journal Article
%T Contribution to the Determination of In Vivo Mechanical Characteristics of Human Skin by Indentation Test
%A Marie-Ang¨¨le Abellan
%A Hassan Zahouani
%A Jean-Michel Bergheau
%J Computational and Mathematical Methods in Medicine
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/814025
%X This paper proposes a triphasic model of intact skin in vivo based on a general phenomenological thermohydromechanical and physicochemical (THMPC) approach of heterogeneous media. The skin is seen here as a deforming stratified medium composed of four layers and made out of different fluid-saturated materials which contain also an ionic component. All the layers are treated as linear, isotropic materials described by their own behaviour law. The numerical simulations of in vivo indentation test performed on human skin are given. The numerical results correlate reasonably well with the typical observations of indented human skin. The discussion shows the versatility of this approach to obtain a better understanding on the mechanical behaviour of human skin layers separately. 1. Introduction Human skin is the largest organ of the human body. The skin protects the body against external influences by preventing fluid loss when exposed to sun, the penetration of undesirable substances in case of pollution, and the development of diseases due to the direct application of external chemical or mechanical loads linked to clinical problems, surgery, or aesthetic treatments. The answers of this barrier to these chemical, biological, mechanical, and thermal loads depend on the person, the site on the body, the age, the health, its nutritional status, its properties, its state (intact or damaged), and its evolutions [1]. Numerous studies have shown that human skin has a stratified structure consisting from the skin outer surface inward of three main layers: the epidermis (composed of the stratum corneum and the viable epidermis), the dermis, and the hypodermis [2¨C6]. Dryness, microcracks, and loss of elasticity are thought to be influenced by fluid flow and the associated changes in ion concentration as a direct result of mechanical stress states. However, these phenomena are complex to understand and to model due to the strong couplings that exist between them and due to the complex behaviour of the different layers of skin soft tissues. Studies of the mechanical behaviour of human skin have observed that the skin is a stratified nonhomogeneous, anisotropic, nonlinear viscoelastic material which is subjected to a prestress in vivo [7¨C9]. In addition its properties vary with age, throughout the body and per person. Difficulties arise when trying to obtain quantitative descriptions of mechanical properties of the skin. Numerous mechanical experiments have been performed on the skin: tensile testing, suction methods, torsion tests, and indentation experiments [10¨C16].
%U http://www.hindawi.com/journals/cmmm/2013/814025/