Novel Design of Hollow Coils for TMS to Minimize the Heat without Reducing Magnetic Field Intensity

Abstract

Transcranial magnetic stimulation (TMS) is a non-invasive neurom odulation technique used to treat various neurological disorders, including major depression. Since the cerebellum is a complex structure connected almost throughout the central nervous system, TMS has gained popularity in the field of cerebellar neurostimulation and promises to stimulate cerebellar activity non-invasively. The TMS coil structure and material play significant roles in achieving the focality of the coil. However, few studies have proposed various structures of solid coils, such as figure-of-eight (FOE) and butterfly-shaped coils to increase the focality of the coil. However, it is observed that there is always a trade-off between the field intensity and the temperature of the coil. In this study, new designs of TMS coils were proposed to reduce the temperature of the coil without significantly reducing the magnetic field intensity. Finite-element simulation tools such as ANSYS Maxwell ® and FEMTET® were used to simulate the field intensity and thermal analysis. The proposed design included hollow coils, double-layered hollow coils, and enamel-layered hollow coils.