Human Skin Micro-Mechanics Measured in Vivo Using Atomic Force Microscopy(AFM)

Detecting mechanical properties of the intact skin in vivo can lead to a quantitative method that can diagnose skin diseases and can monitor skin conditions in long period of time in clinical setting. Current methods either measure human skin mechanics in-vitro in non-physiological conditions or measure the human skin mechanics in larger scale where mechanics of the underneath tissues are also captured. This study demonstrates the feasibility of measuring the human skin mechanics in vivo in micro scale for the first time in which only mechanics of the surface layer of the skin (stratum corneum) is captured. In this study, atomic force microscope (AFM) micro-scale indentation was used for detecting the skin elastic modulus of the finger of four human subjects as well as a fixed/dried skin samples in vitro. The measured elastic moduli (mean value of 23 MPa and standard error of 3 MPa) are in the same range as those reported in literature. As expected the moduli of the fixed/dried skin was more than one order of magnitude harder with elastic moduli at mean value of 703 MPa and standard error of 13 MPa. More works is needed to improve the measurement technique and extend its use for testing skin of other body locations such as face.