Dependence of electromagnetic fields in human brain on coil bending angle in transcranial magnetic stimulation

This paper presents numerical simulation of transcranial magnetic stimulation by employing figure-of-eight coil (fo8) with bending wings. Various fo8 coils with different bending angles were numerically designed. Three-dimensional distributions of the magnetic fields and induced electric fields in realistic head model were calculated by impedance method. Results were compared with those obtained from standard fo8 coil. Results show that either stimulation depth or focality is easily adjusted by changing the bending angle of coil wings. The fo8 coil with flexible folding wings can be served for providing controllable stimulation depth and focality in TMS applications.