| Transcranial magnetic stimulation is a relatively new technique of non-invasive and painless technology of the central and peripheral neural tissues. It takes advantage of low-frequency time-variant magnetic field to couple external energy into human neural-muscular system. In the past decades, magnetic stimulation has grown dramatically in popularity and been used in several applications in medical and clinical research.Firstly, based on the sphere head model, the characteristics of the electric fields induced by arbitrary stimulation coil are analyzed under spherical coordinate and cylindrical coordinate. It is lay the foundation for the simulation for the future.The 3D realistic head model has been build from MRI images. The distribution of electromagnetic field during the magnetic stimulation on the head has been analyzed using ANSYS software. Using the simulation the electromagnetic fields produced by three different kinds of coils have been analyzed. They are circle coil, circle array coil and 8-shaped coil.According to regulation mechanism of sleep, the part is identified that the sleep-induced magnetic coil stimulates. The needs of magnetic field intensity and distribution of forms are also identified. Relating to the analysis in Chapter III , coil form is selected. Using the finite element analysis software ANSYS, in two-dimensional state the size of the coil are analysed to determine the geometric parameters of the coil. Based on combined circuit and the magnetic field theory, we design the coil for the magnetic-induced sleeping instrument.Finally, the intensity of magnetic induction of the designed coil is measured, in order to get the real distribution of the magnetic field. It was compared with theoretical value to verify the correctness of the design. A simple clinical trial is designed to prove that the magnetization-induced sleeping instrument is effective. The result reflected the stimulation coil design is reasonable. |
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