Phenomenological Test Method to Assess of Material Symmetry in Thick Soft Tissues

Characterizing the material symmetry of a biological soft tissue can aid in understanding and modeling its mechanics. Optical methods have been reported for identification of structural fiber orientations in thin tissues such as heart valve leaflets [1], but not in thick tissues such as arteries because optical methods are not as effective with thick tissues. Besides fiber architecture, effective transmural material symmetry of a planar tissue needs to be known a priori in order to perform and interpret common testing methods such as planar biaxial testing or inflation testing (for cylindrical specimens). Nielsen et al. [2] reported on planar radial testing to study inhomogeneous properties of elastic membranes. We submit that planar radial extension testing (PRET) of a thick circular soft tissue specimen will reveal the underlying material symmetry. We performed numerical simulations of planar radial extension testing and assessed its feasibility using a simple custom-fabricated device.