Biomechanics
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Overview
Author:
Edoardo Mazza
The study of the mechanical properties of living tissues is a
fascinating and challenging application of continuum mechanics: soft biological
tissues are inhomogeneous, viscoelastic, anisotropic and are typically subjected
to large deformations. The definition of mathematical models for the description
of their mechanical behavior requires the application of sophisticated
experimental techniques. The construction, execution,
analysis and interpretation of advanced experiments for the characterization of
the mechanical behaviour of soft biological tissue represent our main
contribution to this field.
We use the “aspiration
device” for quasi-static measurements, the “torsional
resonator device” for in-situ high frequency shear testing, the “inflation
device” and the biaxial materials
testing machine for multiaxial experiments with bio-membranes (e.g.
liver capsule, fetal membranes). Our studies are motivated by medical
applications:
(i) diagnosis (detection of liver pathologies; malfunctioning, “incompetent”
uterine cervix; premature rupture of
fetal membranes,
(ii) surgery planning (facial
tissue models for plastic
surgery simulations),
(iii) tissue replacement and implant development (intervertebral
disc, supportive implant meshes for hernia or laxity).
Intra-operative application of our devices provides
information on the in vivo mechanical behavior of human organs (as opposed to
more common observations on specimen from animal organs or extracted from the
human body). We have performed a large number of in vivo aspiration experiments
on human liver, thus building a unique
set of quantitative data on the in vivo mechanical response of this organ. Our
measurements on the uterine cervix of pregnant women provided first objective
data on the evolution of the compliance of the cervix during the gestation. These measurements might represent the
starting point for a new medical procedure for predicting pre-term delivery.
The experimental observations are analyzed using nonlinear
viscoelastic constitutive models (inverse problem). Different model formulations are evaluated in their capability of
describing soft tissue response under uniaxial and multiaxial loading states. Recent efforts
were towards a correlation between mechanical parameters and histological
observations or biochemical indices characterizing tissues microstructure (e.g.
for human liver and fetal membranes).
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Methods
Tissue aspiration
experiment
Torsional resonator
Membrane inflation
experiment
Biaxial materials
testing machine
Inverse problem
Histology/biochemistry/microscopy
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Current
Projects
Mechanical behavior of
the uterine cervix during pregnancy
Deformation and rupture
properties of human fetal membranes
Physically based
modeling of human liver
Mechanical properties of
the intervertebral disc
Mechanical
characterization and modeling of mesh implants
3D face modeling
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Financial
support given by
ETH Zurich
NCCR Co-Me (Swiss National
Science Foundation)
Johnson &
Johnson Medical
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Partners
Dr.
Mahmood Jabareen, Technion, Haifa, Israel,
http://cee.technion.ac.il/eng/
PD
Dr. Andreas Zisch, USZ, Obstetrics and Gynecology,
http://www.geburtshilfe.usz.ch/
PD
Dr. Michael Bajka, USZ, Obstetrics and Gynecology,
http://www.geburtshilfe.usz.ch/
Prof.
Dr. R. Zimmermann, USZ, Obstetrics and Gynecology,
http://www.geburtshilfe.usz.ch/
PD
Dr. Daniele Perucchini, USZ, Obstetrics and Gynecology,
http://www.gynaekologie.usz.ch/
Dr.
David Scheiner USZ, Obstetrics and Gynecology,
http://www.gynaekologie.usz.ch/
Prof. Dr. Jan Deprest, K. University Leuven,
http://www.kuleuven.be/cst/
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
NCCR
Co-Me (Swiss National Science Foundation),
http://co-me.ch/
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Publications
PhD theses
Student projects
Peer reviewed papers
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