Relevance of Indentation Test to Characterize Soft Biological Tissue: Application to Human Skin

Abstract

This contribution presents a new investigation to identify the viscoelastic parameters of soft biological materials using indentation test. The purpose is to present a new independent method on experimental specificities in order to characterize these materials. The identification was done using inverse analysis based on combining finite element (FE) numerical simulations and experimental indentation tests. By considering soft tissues as an isotropic linear viscoelastic material, we firstly validate our proposed FE model via a comparison between analytic and numerical indentation responses. Secondly, the existence and uniqueness of inverse problem solution based on the comparison of numerical/numerical responses is shown. Finally, we validate the stability of the inverse approach using sensitivity analysis by setting up a design of experiment (DOE) technique which proves the relevance of this proposed method. An application is made on the forearm of human skin and shows performances of this proposed method to identify viscoelastic human skin properties in spherical loading–unloading indentation test. This method can be applied to evaluate other viscoelastic materials.

The Effect of the Size of the Sample on Results of Indentation Tests

“…It means that in such an experiment, the relative dimensions of the sample H R and L R should provide stress strain field with uniform distribution on the free surface of the cylinder. This finding is also applicable to the selection of sample sizes for live tissue tests [21].…”

“…In particular, the scale factor affects the indentation curves, which many researchers use to determine the elastic constants of the material [1,2,3]. This is especially true of the so-called nanoindentation [21]. The results of experiments on nanoindentation will only reflect the essential properties of the material when the material sample is sufficiently "large" in comparison with the radius of the spherical indenter.…”

Three-Temperature Boundary Element Modeling of Ultrasound Wave Propagation in Anisotropic Viscoelastic Porous Media

“…One of the computational strategies used to solve the bioheat transfer problems of biological tissues [20][21][22] is the boundary element method (BEM) [23][24][25][26][27][28][29][30][31]. For physical and technological problems, Laplace-domain fundamental solutions are generally easier to get than time-domain fundamental solutions [32,33]. As a result, because it requires the Laplace-domain fundamental solutions of the problem's governing equations, the CQBEM is highly useful for problems that did not have time-domain fundamental solutions.…”

Three-Temperature Boundary Element Modeling of Ultrasound Wave Propagation in Anisotropic Viscoelastic Porous Media

“…One of the computational strategies used to solve the bioheat transfer problems of biological tissues [20][21][22] is the boundary element method (BEM) [23][24][25][26][27][28][29][30][31]. For physical and technological problems, Laplace-domain fundamental solutions are generally easier to achieve than time-domain fundamental solutions [32,33]. As a result, because it requires the Laplace-domain fundamental solutions of the problem's governing equations, the CQBEM is highly useful for problems that did not have time-domain fundamental solutions.…”