Polarization in a Uniform Dielectric

Polarization is a difficult concept, widely but differently used. In Section 7.9, we will focus on the polarization of electrodes. In the present section, we will focus on the polarization of biomaterials. Basically, we are focusing on static polarization with bound charge carriers. Such polarization is a key concept in understanding the electrical properties of tissue because it covers some very important and characteristic phenomena. We will start with the most general definition of polarization, and then differentiate. 

Polarization in a biomaterial volume is the electric field—induced disturbance of the charge distribution in that volume. 

All materials are polarizable, but vacuum is not (although it can hardly be called a material). With only bound charges, an electric field can only displace charges so that dipoles are formed and the material is polarized. If the hiomaterial is dry, double layers (Section 7.5) will not be formed. A dry hiomaterial in contact with dry electrode metal forms an interface. With free charges, there are important additional effects from the migration of these in an electric field. 

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