Dust flux, Vostok ice core

Dust flux, Vostok ice core
Two dimensional phase space reconstruction of dust flux from the Vostok core over the period 186-4 ka using the time derivative method. Dust flux on the x-axis, rate of change is on the y-axis. From Gipp (2001).

Thursday, June 20, 2013

The body piezoelectric

Piezoelectricity is all around you, from the clocking chips in computers and watches, to the transducers in certain sonars, to many of the tissues in your body. Piezoelectricity is a phenomenon in which a crystal which is subject to stress develops an electric field. It is reversible, so that applying an electric field across a piezoelectric crystal causes it to distort.

We are accustomed to thinking of piezoelectricity as being restricted to crystals and ceramics. But tissues in the body are piezolelectric as well. The initial discovery (though long suspected - pdf) of piezoelectric behaviour in bone was followed up by its discovery in neurons, intestinal tissue, cartilage, tendons, and ligaments.

The piezoelectric effect may play a role in crystal growth, as when pressure is applied to the crystal, the maximum potential differences will tend to be at the ends of the crystal, so that ions are more likely to report there rather than the middle.

It has long been recognized that the piezoelectric effect is responsible for bone remodeling which is why you should make an effort to stand up straight and don't slouch!

- - - - - - - - - - - -

This story about cellphone towers prompted today's topic. I have long been sympathetic towards the notion of non-heating damage from non-ionizing radiation. Piezoelectricity is a possible mechanism for harm, although there is no study of which I am aware that shows this. The possible mechanism for harm is difficult to elaborate, because the role of electric fields in these various tissues is uncertain. Piezoelectric materials may undergo a distortion when they are subject to external electric fields, which may contribute to vascoconstriction. It's also possible that the external electric fields may also interfere with the growth of these structures.

No comments:

Post a Comment