Finite element simulation for the mechanical characterization of soft biological materials by atomic force microscopy. (September 2016)

• Record Type: Journal Article
• Authors: Valero, C.; Navarro, B.; Navajas, D.; García-Aznar, J.M.
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 62(2016)
• Page Start: 222
• Page End: 235
• Publication Date: 2016-09
• Subjects: Nanoindentation -- AFM -- FEM -- Soft-tissue -- Cell mechanics; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2016.05.006
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: The characterization of the mechanical properties of soft materials has been traditionally performed through uniaxial tensile tests. Nevertheless, this method cannot be applied to certain extremely soft materials, such as biological tissues or cells that cannot be properly subjected to these tests. Alternative non-destructive tests have been designed in recent years to determine the mechanical properties of soft biological tissues. One of these techniques is based on the use of atomic force microscopy (AFM) to perform nanoindentation tests. In this work, we investigated the mechanical response of soft biological materials to nanoindentation with spherical indenters using finite element simulations. We studied the responses of three different material constitutive laws (elastic, isotropic hyperelastic and anisotropic hyperelastic) under the same process and analyzed the differences thereof. Whereas linear elastic and isotropic hyperelastic materials can be studied using an axisymmetric simplification, anisotropic hyperelastic materials require three-dimensional analyses. Moreover, we established the limiting sample size required to determine the mechanical properties of soft materials while avoiding boundary effects. Finally, we compared the results obtained by simulation with an estimate obtained from Hertz theory. Hertz theory does not distinguish between the different material constitutive laws, and thus, we proposed corrections to improve the quantitative measurement of specific material properties by nanoindentation experiments. Graphical abstract: Highlights: Study of nanoindentation of a biological fibrous material with different orientations. Determination of the sample size required to quantify the mechanical properties of soft materials. Corrections for adjusting Hertz theory to different material model behaviors.