Optimization Design Of Magnetic Targeting And Focusing Coil Array Based On Improved Genetic Algorithms

Recently, researchers all around the world have begun efforts in study of the magnetic targeted drug delivery system, which is a new method for anticancer therapy. It has the significant value and wide application foreground because of its non-invasiveness and high targeting efficiency. The orientation external magnetic field is the key influencing factor of treatment effect. Compared with the simple permanent magnet, it is more flexible, convenient and has strong operability to get external magnetic from coil array. The target position, magnetic field intensity and focus range can be adjusted by changing the assignment and the excitations of the coil array.The magnetic targeting and focusing coil array based on improved genetic algorithms was introduced in this dissertation, and made comprehensive optimization of its focusing performance. Based on the basic theory of electromagnetic field and three-dimensional finite element theory, we designed the parameters and structure of the single coil. On this basis, three different types of coil array were introduced. The planar coil array was chose after contrasting their focusing performance. Then, we studied the basic principle and theory of genetic algorithms and made some improvement, and applied improved genetic algorithms to calculate the currents of stator coils. Finally, the targeting and focusing effect was proved by simulation, space magnetic field measurement and practical tests.The main research works of this paper include:①Designed the parameters and structure of the single coil to get better focusing performance. We analyzed the influence of the number of turns, the inside diameter and the winding mode to the magnetic flux density distribution of single coil via further study of the basic theory of electromagnetic field and three-dimensional finite element theory. To increase the magnetic flux density and the focusing depth on the targeting position and make the focusing performance better, we analyzed the axial and radial distribution of magnetic flux density respectively. Finally, we determined the parameters of 6 turns and 2cm of inside diameter, and the coil under one of the transmutations of coils of multilayer.②Designed the coil array to get better focusing performance. Based on the designed single coil, three types of coil array were improved, which were hemispherical, planar, and circular coil array. In the simulation, the same excitation was applied to them. We analyzed the results and combined with the feasibility, the planar coil array was chosen. Furthermore, we realized the focusing of non-central point and multi-point with multilayer planar coil array.③Calculate the currents of the stator coils using the improved genetic algorithms. We studied the basic principles and conceptions and solution process of the simple genetic algorithms. Then, we made improvement in getting the first generation, finding missed gene, and protecting the best individual. On this basis, we built model to calculate the currents of the stator coil in coil array and get the good focusing performance and high energy efficiency.④Based on the design scheme, we put up the model of coil array and measured the magnetic flux density distribution on the targeting position applying the measurement platform. The results verified focusing performance of the coil array. Furthermore, the practical test was made to observe the focusing effect.