Biological Ferroelectricity Uncovered in Aortic Walls by Piezoresponse Force Microscopy

PRL 108,
078103
(2012),  http://prl.aps.org/abstract/PRL/v108/i7/e078103

See also Physics Viewpoint by Bin and Huajian, http://physics.aps.org/articles/v5/19

Inside Science News Service, http://www.insidescience.org/news-service/1.2462

Science Daily, http://www.sciencedaily.com/releases/2012/01/120130170149.htm

Many biological tissues are piezoelectric and pyroelectric with
spontaneous polarization. Ferroelectricity, however, has not been
reported in soft biological tissues yet. Using piezoresponse force
microscopy, we discover that the porcine aortic walls are not only
piezoelectric, but also ferroelectric, with the piezoelectric
coefficient in the order of 1  pm/V and coercive voltage
approximately 10 V. Through detailed switching spectroscopy mapping and
relaxation studies, we also find that the polarization of the aortic
walls is internally biased outward, and the inward polarization switched
by a negative voltage is unstable, reversing spontaneously to the more
stable outward orientation shortly after the switching voltage is
removed. The discovery of ferroelectricity in soft biological tissues
adds an important dimension to their biophysical properties, and could
have physiological implications as well.