Optimum Design of Continuously Workable Transcranial Magnetic Stimulator

As a new non-invasive biotechnology, transcranial magnetic stimulation (TMS) is widely used in the treatment of various psychiatric diseases. The stimulation coil of traditional transcranial magnetic stimulator produces a lot of Joule heat during treatment procedures, which leads to low stimulation efficiency. However, discussion about heating problem in TMS is very limited. In this paper, a new transcranial magnetic stimulator which can work continuously is proposed. Its stimulation coil is wound with hollow copper wire and the central hollow part is used to circulate low-temperature deionized water. The cooling deionized water is provided by a small silent chiller. The Joule heat generated during medicals treatment is taken away by the cooling deionized water, so that the temperature of the stimulation coil can be maintained within a safe range. Finite element method is adopted to analyze the intracranial induced electrical field produced by the water-cooling stimulation coil (WSC). Geometric structure of WSC is optimized based on minimum Joule heat. Design of cooling parameters is carried out with coupled multi-physical field analysis. Results prove that the WSC is able to generate the required intracranial induced electrical field. When 3000 pulses are applied, the temperature of the new transcranial magnetic stimulator could be maintained at room temperature, while the temperature rise of the magnetic stimulation without water cooling is 57 K.