Study On The Focusing Of Transcranial Magnetic Stimulation System

Transcranial magnetic stimulation (TMS) technology developed in recent years is a painless, non-invasive, green treatment and detection method. It has great development potential in the field of biomedical research and medical research. However, because of the difference in the efficiency of the stimulation system, the technology is not widely used. The focality of the magnetic field is one of the key issues that affect the efficiency of magnetic stimulation. The poor performance of the focality is the target position can not be stimulatd and repetitive stimulation is very poor. If the focusing problem can not be solved, the development of TMS technology will be restricted. Therefore, the research of focusing has become a hot spot in recent years. In order to study the focality of transcranial magnetic stimulation, the main works of this thesis are as follows.1、A hybrid algorithm is proposed based on a simplified particle swarm optimization algorithm (sPSO) and simulated annealing (SA) algorithm. The convergence and convergence speed of the algorithm are tested. The co-simulation of COMSOL and MATLAB is utilized. The currunt through the coils are optimized and solved. The simulation results show that the hybrid algorithm made up by sPSO and SA to optimize the parameters can improve the focality performance. The co-simulation of COMSOL and MATLAB can be used in focality performance optimization and improve the accuracy.2、The influence of resistance, capacitance and inductance on the characteristics of the pulse current and the magnetic field distribution in the head model are analyzed. The influence of the rotation angle of the coil around the axis on the focusing properties of the magnetic field in the head model is studied. The 5 coils array is established and the related parameters are configured by using the results of the research:the current of the coil, the discharge loop parameters and coil placement angle relative to the head model. Finally, the optimization of the focusing effect of the model is realized. After optimization, the area of more than 80% Bmax is significantly smaller than that of the not optimized, and focusing waveform is more steep.There is only the peak without side peak.3、The circuit of the pulse current is set up. According to the requirements of the parameters of the circuit, the device is selected, and the control circuit of IGBT is designed. Finally, the circuit diagram of the circuit is set up, and the pulse current with high current change speed and amplitude is generated.The proposed optimization algorithm and the study to the parameters of the discharge circuit are useful to enhance the focality of the TMS technology in the further development.