Simulation And Experimental Research On The Aggregation Performance Of Magnetic Particles Under Magnetic Field

The magnetic manipulation technique using gradient magnetic force to realize the targeted motion of magnetic micro/nanoparticles has broad applications in targeted drug therapy, gene transfection and biological target areas. However, besides the gradient magnetic force induced by an applied gradient field, the interaction force between particles is also acting on magnetic particles. Furthermore, the latter force leads to magnetic aggregation phenomenon, and this phenomenon will affect the motion characteristics of the targeted particles. Existing research is more focused on motion behavior of magnetic particles under a single gradient magnetic force mode, while aggregation phenomenon under magnetic field(especially gradient magnetic field) and its effect on targeted motion has not won enough attention. Based on this, this paper presented numerical analysis of magnetic particle aggregation behavior under magnetic field and investigated the effect of magnetic aggregation phenomenon under gradient field on the targeted behavior.In view of numerical analysis of magnetic particle aggregation behavior under magnetic field, this paper established a fluid- solid coupling dynamic model of the magnetic particles under the combined effect of magnetic field and flow field. Stress tensor and finite element method(ST-FEM) for calculating the magnetic and hydrodynamic forces acting on the magnetic particle during aggregation, which greatly improved solution accuracy, can be used to analyze the dynamic characteristics of the magnetic particles in the aggregation process. The principle of calculating magnetic and fluid field force based on ST-FEM is presented and the method is verified. Finally the paper analyzed the aggregation behavior based on the simulation results applying COMSOL.In the respect of the effect of magnetic particle aggregation phenomenon under gradient magnetic field on the targeted behavior, this paper introduced and compared dynamic behavior of magnetic particles in two kinds of permanent magnet models(magnetic field in the region of magnetic solution in the negative x-direction, or ydirection), revealing the potential effect of aggregation on the targeted behavior. This paper:(1) studied the theory analysis and the principle of force imposed on the magnetic particles in the two models;(2) exposed the magnetic field distribution and gradient field force directions based on COMSOL modeling, and analyzed the aggregation and moving character of particles;(3) simulated the motion performance of particles in the two models, utilizing Monte-Carlo method;(4) experimentally verified the forecast on particles behavior proposed by(1)and(2). This paper analyzed the similarities and differences of aggregation and motion characteristic of magnetic particles under different field, which has provided the experimental evidence for enhancing drug targeting delivery and magnetofection efficiency.