Optimized Design of a Figure-Eight Coil for Transcranial Magnetic Stimulation

This paper proposes an optimized design methodology for figure-eight coils, aiming to minimize coil losses meanwhile preserve magnetic field focusing capabilities. Through the optimization, the coils enhance the therapeutic effectiveness of transcranial magnetic stimulation (TMS). Then, the analytical expressions are validated, including calculating the focused magnetic field, power losses, temperature rise, and inductance of a figure-eight coil. By employing the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to optimize the coil parameters, we get the results of Pareto-optimal set of solutions that simultaneously meet magnetic focusing performance and temperature rise constraints. Comparing to traditional optimal, the losses decrease hugely and the inductance of coil meets the demand of requirement.