Variation of Streaming Potentials with Time under Steady Fluid Pressure in Bone

Abstract

This paper investigates the streaming potentials’ behaviors when fluid flows through the micropores in bone. An experimental setup was developed for measuring the streaming potentials between two surfaces of a bone plate specimen. It was found that the streaming potentials measured increased almost linearly with time under a constant fluid pressure gradient, which does not agree with the prediction from the classical theory of streaming potentials. To explain the reasons associated with the results obtained, a theoretical model was proposed in which the electric charge densities on the inner surfaces of the capillary are unevenly distributed. A formula was developed for solving the model, and the solutions demonstrate that nonuniform accumulations of electric charges carried by the fluid on the inner surfaces of the microcanals in bone can induce streaming potentials which linearly increase with time during the driving air pressure holding period. This phenomenon represents the specific characteristics of bone. The solution implies that the streaming potentials in Haversian canals, lacunas and canaliculi are not affected by electro-viscous resistance in the bone fluid.