Control of the orientation of human erythrocytes by magnetic and electric fields

Abstract

The orientation of human red blood cells (RBCs) was controlled by the application of magnetic and electric fields. Because of their anisotropic diamagnetism, RBCs orient parallel to strong magnetic fields. The electric orientation of erythrocytes is also caused by electric dipoles induced by an electric field. The RBCs orientation is parallel to both the electric and magnetic fields. A 4–5 kV/m alternating current (ac) electric field (10–200 kHz, sine wave) was applied to RBCs suspended in a phosphate buffer solution using a pair of platinum black electrodes spaced 200–250 μm apart. An 8 T magnetic field was applied to the RBCs perpendicular to the direction of the electric field. It was observed that all RBCs were oriented in the same direction and parallel to the electric and magnetic fields. By the application of a horizontal 8 T magnetic field and a 4 kV/m ac electric field positioned perpendicular to one another, the RBCs oriented horizontally and their sedimentation rate was decreased by 18%. The flowing rate of the 10% RBCs suspension was decreased by 7.6% with the application of an 8 T magnetic field and a 4 kV/m ac electric field perpendicular to the direction of the suspension flow. It was observed that flowing RBCs were oriented perpendicular to the direction of the flow by the application of the fields, when the velocity of the suspension of RBCs was less than 300 μm/s.