Targeting Behavior of Magnetic Particles Under Gradient Magnetic Fields Produced by Two Types of Permanent Magnets

Fully understanding the dynamics of particles induced by magnetic fields with considering particle-particle interaction is an interesting and important issue for delivering magnetic particles to a target site with a high efficiency. For this purpose, permanent magnets with horizontal and vertical magnetization directions respectively have been taken for generating two types of gradient magnetic fields, which are applied to produce similar gradient magnetic forces while with different magnetic interaction forces between particles. On this basis, the distributions of particles under the two gradient magnetic fields are investigated and compared using Monte Carlo simulations. The results show that the concentrated particles have chainlike structures and their distributions are configuration dependent with the magnetization direction of permanent magnets: parallel and perpendicular to the bottom line for horizontal and vertical magnetization directions, respectively. Above all, a detailed microscopy study reveals that the movement trajectories of magnetic particles are affected by both transport and aggregation behavior of particles and the microscopic visualizations of particle distributions in the target region are in agreement with simulation predictions.