Research On Dynamic Behavior And Manipulation Of Magnetic Fluid In Magnetic Targeting System

With the development of magnetic nano-materials and multi-functional polymer materials in recent years, the magnetic targeting system based on nano-magnetic fluid has become an important delivery system for high target and controllable performance, which can be an effective research tool in drug/gene targeting delivery, cancer therapy, magnetic separation and microfluidic chip. However, due to the fact that the magnetic targeting system involves an interdisciplinary research of electromagnetics, fluid mechanics, and nano-technology, the magnetic targeting technology at home and abroad is still under development, especially in the fields of targeting mechanism, targeting behavior control and targeting system optimzation.In the respect of the targeting mechanism, the paper has established a coupling mathematical model of magnetic field, flow field, and concentration field for the hydrodynamics of magnetic fluid under magnetic field based on the basic principles of electromagnetism and fluid mechanics, taking into account the non-linearity magnetization performance of the magnetic fluid and the effect of magnetic body force on the fluid flow behavior. On this basis, a numerical simulation is presented to study the variation law of the magnetic fluid in the pipe under gradient magnetic field and the effects of flow velocity, magnetic field source structure and magnetic parameters on the magnetic fluid dynamic behavior, which can be used to further understand the mathmatical model.In view of the aggregation phenomenon of magnetic particles under magnetic field, the paper studies the particle aggregation phenomenon by simulating the random movement behavior of magnetic particles under magnetic field with Cluster-moving Monte Carlo method. And the effects of magnetic field direction and magnetic energy on the aggregation morphology are analyzed. On the basis, the paper points out that the possible main reason for the increase of the particle speed in the experiment is that the viscous-fluid drag force acting on the particles is reduced due to the aggregation behavior. Meanwhile, the aggregation mechanism is studied by analyzing the magnetic interaction energy and force in magnetic particle system under magnetic field.In the respect of the targeting behavior control, through the mathematical model of the magnetic force, the paper points out that the magnitude and direction of magnetic force can be controlled by independently adjusting magnetic field strength and magnetic field gradient parameters. And a compound magnetic field source system with one uniform magnetic field and one gradient magnetic field is proposed. Based on the field source, the dynamic targeting behavior of magnetic fluid in the microfludic system is studied and an effective micro-mixer system is designed. Then the effects of current frequency, inlet velocity and magnetic body force on the regularity and efficiency of fluid mixing in the microchannel are investigated, which can be used as basis and instruction for the optimum design of magnetic micro-mixer.In the respect of optimum design for magnetic targeting system, the paper firstly investigates the influence of coil’s parameters on the gradient and uniformity of the target field for the thick-wall Maxwell coils by the co-simulation method of Comsol and Matlab. Then it points out that the traditional design method for thick coils is not reasonable and the optimum design for the coil is very necessary. On this basis, an electromagnetic optimization model of magnetic source system with finite element analysis and adaptive hybrid genetic algorithm is set up. And then the paper realizes the optimizations of thick-wall Maxwell coils and permanent array system well.Finally, due to the fact that the drug and receptor activation efficiency is low in existing drug screening system, this paper introduces the magnetic targeting technique to improve the effective drug concentration in the vicinity of the cell surface receptor. And thus it can effectively enhance the efficiency of drug and receptor activation. On this basis, a magnetic targeting system, which can generate the uniform magnetic force in the region of96-well plates force, is designed and used to carry out preliminary experimental study of drug and GPCR activation characteristics.