Ferroelectricity and piezoelectricity in soft biological tissue
Porcine aortic walls revisited
Thomas Lenz (Max Planck Institute for Polymer Research, Graduate School Materials Science in Mainz)
Regina Hummel (Johannes Gutenberg-University Mainz)
Ilias Katsouras (TNO)
Wilhelm A. Groen (TNO, Novel Aerospace Materials)
M. Nijemesland (TU Delft - Delft Aerospace Structures and Materials Laboratory)
Robert Ruemmler (Johannes Gutenberg-University Mainz)
Michael K.E. Schäfer (Johannes Gutenberg-University Mainz)
Dago M. de Leeuw (Max Planck Institute for Polymer Research, Novel Aerospace Materials)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Recently reported piezoresponse force microscopy (PFM) measurements have proposed that porcine aortic walls are ferroelectric. This finding may have great implications for understanding biophysical properties of cardiovascular diseases such as arteriosclerosis. However, the complex anatomical structure of the aortic wall with different extracellular matrices appears unlikely to be ferroelectric. The reason is that a prerequisite for ferroelectricity, which is the spontaneous switching of the polarization, is a polar crystal structure of the material. Although the PFM measurements were performed locally, the phase-voltage hysteresis loops could be reproduced at different positions on the tissue, suggesting that the whole aorta is ferroelectric. To corroborate this hypothesis, we analyzed entire pieces of porcine aorta globally, both with electrical and electromechanical measurements. We show that there is no hysteresis in the electric displacement as well as in the longitudinal strain as a function of applied electric field and that the strain depends on the electric field squared. By using the experimentally determined quasi-static permittivity and Young's modulus of the fixated aorta, we show that the strain can quantitatively be explained by Maxwell stress and electrostriction, meaning that the aortic wall is neither piezoelectric nor ferroelectric, but behaves as a regular dielectric material.