Enhanced separation of magnetic and diamagnetic particles in a dilute ferrofluid

Traditional magnetic field-induced particle separations take place in water-based diamagnetic solutions, where magnetic particles are captured while diamagnetic particles flow through without being affected by the magnetic field. We demonstrate that replacing the diamagnetic aqueous medium with a dilute ferrofluid can significantly increase the throughput of magnetic and diamagnetic particle separation. This enhancement is attributed to the simultaneous positive and negative magnetophoresis of magnetic and diamagnetic particles, respectively, in a ferrofluid. The particle transport behaviors in both ferrofluid- and water-based separations are predicted using an analytical model.