A magnetic stimulator coil with high robustness to positioning error

Transcranial magnetic stimulation (TMS) is effective for treatment of neurological diseases such as neuropathic pain. We are newly developing magnetic stimulators for use at patient´s home for realizing daily treatment. One of the technical challenges is a system for positioning the stimulator coil. In this study, we proposed a coil design which gives a high robustness to positioning error. We numerically evaluated the characteristics of the coil when changing the width, depth, height, and the number of turns of the coil. The results showed that the mostly influencing parameter on the broadening of the eddy current was the width of the coil, and the vertical length was influential on the current density. We found the proposed coil induces eddy currents in a wider range than conventional figure-eight coils.