A novel design of transcranial magnetic stimulator

A novel transcranial magnetic stimulator with innovative geometric coil design is proposed in this paper. The stimulator is mainly composed of a charging circuit, a discharge circuit and a stimulating coil. A feedback loop with a bidirectional thyristor is adopted in the discharge circuit to recover energy. The stimulating coil is designed into a coil pair with an irregular form of cambered surface. Finite-Element Method (FEM) is used to analyze the distributions of intracranial induced electromagnetic field. To unify evaluation standard, a comparison function reflecting multiple physiological properties of intracranial induced field is constructed. Comparing to conventional structure, the optimization of this design can enhance the peak of stimulus intensity for 92.29%, raise the value of RPN for 66.75% while improving the overall performance by 166.12%. The new stimulator makes it possible to obtain superior intracranial focusing field in targeted tissues with lower exciting current and the comparison function has important guiding significance for coil design.