Physically based modeling of human liver
This project is focused on detailed mechanical modeling and experimental characterization of soft biological tissues. In particular, the purpose is the formulation and experimental validation of physically based constitutive models representative of tissue-microstructure and related biophysical processes. Research aims at clinical applications (e.g. diagnostics and simulations).
Vascularized tissues are very soft composite structures (typically collagen, GAG, elastin and fluids). They constitute the inner organs of the body. The in vivo mechanical response of vascularized tissues is influenced by biochemical, growth and aging processes. When excised, these tissues rapidly alter their mechanical properties, so that their mechanical behavior has to be characterized in vivo. Analysis of such measurements showed that existing constitutive models (based on quasi-linear viscoelasticity) are inadequate to fully explain the observed mechanical response. To overcome this, more involved microstructural and phenomenological models have been proposed recently (e.g. Rubin, Hurschler and Holzapfel).
In the present project constitutive equations will be used that include terms reflecting the contribution of specific constituents and structural features. For a physically appropriate model, the layered structure of inner organs will be accounted for [9p, 3s]. Integration into a finite element framework enables then direct comparison with experiments.
In vivo measurements are performed using the existing aspiration device. Further, device miniaturization will facilitate the in vivo application during laparoscopic interventions and improve local characterization of the tissue’s mechanical response, [4s].
Dr. med. S. Breitenstein, Department of Visceral and Transplantation Surgery, USZ, http://www.vis.usz.ch
Dr. med. P. Villiger und Dr. med. M.C. Attinger, Kantonsspital Chur, http://www.ksgr.ch