Microelectrode studies of stress-generated potentials in four-point bending of bone

A microelectrode technique has been developed to enable the study of stress-generated potentials (SGP) in bone to a spatial resolution of 5 micrometers. The technique has been used to measure the electrical potentials as a function of bone micromorphology in four-point bending. Electric fields ranging from 30 to 10(3) times greater than is measured by conventional macroscopic methods have been discovered at the Haversian canals for human and bovine cortical bone. The amplitude and direction of the electric field in the osteons depend specifically upon the amplitude and the sign (i.e., compression or tension) of the stress. The implications of this finding with regard to the origin of SGP and their possible physiological significance are considered.