An anisotropic, hyperelastic model for skin: Experimental measurements, finite element modelling and identification of parameters for human and murine skin

Groves, Rachel Beth; Coulman, Sion; Birchall, James Caradoc; Evans, Samuel Lewin

doi:10.1016/j.jmbbm.2012.10.021

Cited by 181 publications

(143 citation statements)

References 41 publications

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“…Wu et al (2006) reported a tensile Young's modulus of 3 MPa at 100% relative humidity (RH) to 370 MPa at 30% RH. Although some authors have developed computational models of the skin (Groves et al, 2013;Limbert, 2011;Ní Annaidh et al, 2012) or the dermis (Flynn andMcCormack, 2009, 2010) which account for the anisotropic properties induced by the presence of collagen fibres, this approach is not followed in the current research for two main reasons. The first reason is motivated by the decision to keep the model as simple as possible to facilitate the interpretation of results and to focus on structural rather than material effects.…”

Section: Mechanical Properties Of Skinmentioning

confidence: 99%

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

Leyva-Mendivil

Page

Bressloff

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

109

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A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.www.elsevier.com/locate/jmbbm 1 A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin. AbstractThe study of skin biophysics has largely been driven by consumer goods, biomedical and cosmetic industries which aim to design products that efficiently interact with the skin and/or modify its biophysical properties for health or cosmetic benefits. The skin is a hierarchical biological structure featuring several layers with their own distinct geometry and mechanical properties. Up to now, no computational models of the skin have simultaneously accounted for these geometrical and material characteristics to study their complex biomechanical interactions under particular macroscopic deformation modes.The goal of this study was, therefore, to develop a robust methodology combining histological sections of human skin, image-processing and finite element techniques to address fundamental questions about skin mechanics and, more particularly, about how macroscopic strains are transmitted and modulated through the epidermis and dermis. The work hypothesis was that, as skin deforms under macroscopic loads, the stratum corneum does not experience significant strains but rather folds/unfolds during skin extension/compression.A sample of fresh human mid-back skin was processed for wax histology. Sections were stained and photographed by optical microscopy. The multiple images were stitched together to produce a larger region of interest and segmented to extract the geometry of the stratum corneum, viable epidermis and dermis. From the segmented structures a 2D finite element mesh of the skin composite model was created and geometrically non-linear plane-strain finite element analyses were conducted to study the sensitivity of the model to variations in mechanical properties.The hybrid experimental-computational methodology has offered valuable insights into the simulated mechanics of the skin, and that of the stratum corneum in particular, by providing qualitative and quantitative information on strain magnitude and distribution. Through a complex non-linear interplay, the geometry and mechanical characteristics of the skin layers (and their relative balance), play a critical role in conditioning the skin mechanical response to macroscopic in-plane compression and extension. Topographical features of the skin surface such as furrows were shown to act as an efficient means to deflec...

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Section: Mechanical Properties Of Skinmentioning

confidence: 99%

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

Leyva-Mendivil

Page

Bressloff

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

109

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show abstract

“…It is interesting to note that despite of the micromechanical motivation and structure of these models, the constitutive equations for the components are usually phenomenological (for example Fung-type for fibers and Neokookean for matrix) and the paramaters of these constitutive models are typically obtained from a fit of the measured experimental behavior on the composite as a whole [6,11,31,32], frequently even using inverse analysis over continuum finite element structures [31,32]; although recently more efforts are placed on using the specific histological data to obtain at least some material parameters. The structure-based approach would suggest to employ just parameters from experimental data of the components and from histological data, avoiding phenomenological, macroscopic fitting of any microstructural material parameter, specially when multiple solutions are possible and frequently reported, see for example [31,32,33]. Furthermore, the computationally efficient General Structure Tensor schemes used in finite element simulations of organs compute continuum stresses from average (and affine) strains of components in a nonlinear problem, which is another approximation which reduces their accuracy [9].…”

Section: Discussionmentioning

confidence: 99%

Determination and Finite Element Validation of the WYPIWYG Strain Energy of Superficial Fascia from Experimental Data

2016

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What-You-Prescribe-Is-What-You-Get (WYPIWYG) procedures are a novel and general phenomenological approach to modelling the behavior of soft materials, applicable to biological tissues in particular. For the hyperelastic case, these procedures solve numerically the nonlinear elastic material determination problem. In this paper we show that they can be applied to determine the stored energy density of superficial fascia. In contrast to the usual approach, in such determination no user-prescribed material parameters and no optimization algorithms are employed. The strain energy densities are computed solving the equilibrium equations of the set of experiments. For the case of superficial fascia it is shown that the mechanical behavior derived from such strain energies is capable of reproduc- * Corresponding author Email addresses: m.latorre.ferrus@upm.es (Marcos Latorre), fany@unizar.es (Estefanía Peña), fco.montans@upm.es (Francisco J. Montáns) Preprint submitted to Annals of Biomedical EngineeringAugust 3, 2016 ing simultaneously the measured load-displacement curves of three experiments to a high accuracy.

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“…For example, number of models have been used to describe the strain rate sensitivity of the material, such as Ogden 12-14 and other approaches. 15, 16 Shergold et al…”

Section: Analytical Modelling Of Skin and Polymersmentioning

confidence: 99%

Composite nature of fresh skin revealed during compression

Butler

Boddy

et al. 2015

Bioinspired, Biomimetic and Nanobiomaterials

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Biological systems are subjected to moderate to high strain rates in blast-type traumatic injuries. An improved understanding of how cells and tissues respond to extreme mechanical stresses could improve mitigation and post-injury treatment strategies. A key aim of our research is to create biologically meaningful injury models of soft tissues. Here we examine the material and cellular properties of freshly harvested porcine skin in compression. Comparative histopathology and analytical modelling suggests that fresh skin differentially responds low to moderate strains rates as a composite rather than that of a homogeneous polymer. The implications of this work are discussed in terms of creating improved analytical models to describe the material behavior of fresh skin.

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An anisotropic, hyperelastic model for skin: Experimental measurements, finite element modelling and identification of parameters for human and murine skin

Cited by 181 publications

References 41 publications

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

Determination and Finite Element Validation of the WYPIWYG Strain Energy of Superficial Fascia from Experimental Data

Composite nature of fresh skin revealed during compression

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