Analysis of human skin mechanical properties by tensile and nanoindentation techniques

last updated: 2019-03-29
ProjectDressing4scars :: publications list
TitleAnalysis of human skin mechanical properties by tensile and nanoindentation techniques
Publication TypeComunications - Poster
Year of Publication2018
AuthorsFernandes M. G., Carvalho A. M., da Silva L. P., Pires R. A., Reis R. L., and Marques A. P.

Skin is a complex organ that covers the entire surface of the human body acting as a protective barrier from the external environment. As a layered tissue with anisotropy, nonlinear and time-dependent mechanical behaviour, the skin has appropriate mechanical properties that allow it to respond correctly to external mechanical loads. However, skin mechanical properties are intricate under different loading conditions which also differ with skin anatomical locations, sex, age, pathology, orientation etc. Although the mechanical behaviour of skin tissue has been largely studied using different testing methods, its complexity leads to a variety and inconsistent range of reported values. Under standardised conditions, the objective of this study was to provide the mechanical properties of human skin as a base to devise new approaches for scarless wound regeneration. Uniaxial tensile testing and atomic force microscopy (AFM) were performed on freshly human skin specimens. Tensile tests were carried out at a strain rate of 0.069 s-1 on skin samples from the abdomen and gluteus, and tapered into a “dog bone” shape with a custom die. Nanoindentation (performed by AFM) was used to quantify the Young’s modulus of skin from abdomen, armpit and gluteus. Force-distance curves were acquired using a quadratic pyramid tip shape under force mapping mode over equally distanced 8 x 8 points in at least 5 different 30 x 30 μm regions in the epidermis of a full-thickness skin sample. Results showed that the skin from the gluteus region has the greatest stiffness (Young’s modulus of 11.12 MPa using uniaxial tensile tests and 6.89 MPa using AFM). Skin tissue from the abdomen region had a Young’s modulus of 3.57 MPa and 1.17 MPa as determined by tensile tests and by AFM, respectively; skin from armpit region presented a Young’s modulus of 2.82 MPa, measured using AFM. Results from uniaxial tensile tests also showed a mean ultimate tensile strength (UTS) of 8.89 MPa and 3.45 MPa for the gluteus and abdomen skin, respectively. Skin mechanical properties collected in this study show that human skin from different sites display appropriated stiffness to respond correctly to external mechanical loads. This topic should be considered in the development of new skin substitutes that would ideally be mechanically indistinguishable from normal skin aiming at reduce the formation of scar tissue and improving wound healing.   

Conference NameGENE2SKIN Final Conference - Cutting-edge basic & translational research in skin-related diseases & disorders
Date Published2018-10-23
Conference LocationGuimarães
Keywordshuman skin, Mechanical Properties, nanoindentation test, tensile test
Peer reviewedno

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