A novel method for visualising and quantifying through-plane skin layer deformations

• Published in: Journal of the mechanical behavior of biomedical materials 2012-10, Vol.14, p.199-207
• Main Authors: Gerhardt, L.-C., Schmidt, J., Sanz-Herrera, J.A., Baaijens, F.P.T., Ansari, T., Peters, G.W.M., Oomens, C.W.J
• Format: Article
• Language: English
• Subjects: Animals; Biomechanical Phenomena; Correlation analysis; Deformation; Dermis; Digital image correlation; Epidermis; Humans; Image Processing, Computer-Assisted; Mechanical Phenomena; Molecular Imaging - instrumentation; Molecular Imaging - methods; Multilayers; Porcine skin; Rheometer; Shear; Shear modulus; Shear strain; Skin; Software; Strain; Stress, Mechanical; Swine; Through-thickness shear strain; Time Factors; Uncertainty
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2012.05.014

Skin is a multilayer composite and exhibits highly non-linear, viscoelastic, anisotropic material properties. In many consumer product and medical applications (e.g. during shaving, needle insertion, patient re-positioning), large tissue displacements and deformations are involved; consequently large local strains in the skin tissue can occur. Here, we present a novel imaging-based method to study skin deformations and the mechanics of interacting skin layers of full-thickness skin. Shear experiments and real-time video recording were combined with digital image correlation and strain field analysis to visualise and quantify skin layer deformations during dynamic mechanical testing. A global shear strain of 10% was applied to airbrush-patterned porcine skin (thickness: 1.2–1.6mm) using a rotational rheometer. The recordings were analysed with ARAMIS image correlation software, and local skin displacement, strain and stiffness profiles through the skin layers determined. The results of this pilot study revealed inhomogeneous skin deformation, characterised by a gradual transition from a low (2.0–5.0%; epidermis) to high (10–22%; dermis) shear strain regime. Shear moduli ranged from 20 to 130kPa. The herein presented method will be used for more extended studies on viable human skin, and is considered a valuable foundation for further development of constitutive models which can be used in advanced finite element analyses of skin. [Display omitted] ► A novel imaging-based method for quantifying skin layer deformations is presented. ► Experimental data provided insights into through-plane shear strain profiles of full thickness skin. ► Study revealed inhomogeneous skin deformation, characterised by low (epidermis) and high shear strain regimes (dermis). ► Shear moduli of the epidermis are up to 4 times higher than those in the dermis. ► Local skin strains can be more than two times higher than global strains.