Electrical phenomena in biorheology

Electric polarization is important in various subjects in biorheology. Piezoelectricity, that is, stress-induced polarization and electric field-induced strain, is demonstrated in a variety of biological materials including polysaccharides, proteins and deoxyribonucleic acid. Complex piezoelectric constant depends on measuring frequency, temperature and water content. Piezoelectric relaxation is related to microscopic internal strain. Stress-induced potential in bone is produced by shear piezoelectricity in collagen fibers and/or streaming potential in conaliculae. The growth of bone is regulated to best resist external force. The controlling signal seems to be the electric potential. Application of small d.c. current or piezoelectric polymer film stimulates the formation of bone in femur of animals. Various techniques of electrical stimulation are clinically used for healing bone fracture. Pulsing electromagnetic field enhances the proliferation of cell culture.