Performance Optimization and Simulation Research of New Coil for Transcranial Magnetic Stimulation Based on Improved Particle Swarm Optimizer

Transcranial magnetic stimulation (TMS) is a noninvasive technology used to treat certain brain disorders. As an important part of the TMS system, the stimulation coil induces the electric field (EF) in the brain, which can change the excitability of nerve tissue. First, a three-layer multicoil (TLMC) is proposed on the basis of the principle of superposition and cancellation of magnetic field (MF). The simulation results in COMSOL show that this structure can significantly improve focality and stimulation strength, but it reduces the depth of stimulation. Second, a novel improved particle swarm optimizer (PSO) is proposed with three improved strategies. The novel improved PSO has higher convergence accuracy and stability in the test function. Finally, we utilized the novel improved PSO to optimize the current configuration and rotation angle of the TLMC three times. The numerical results show that the TLMC after the second optimization can increase stimulation strength by 19.10% on the basis of satisfying the stimulation depth of 15 mm. Compared with the unoptimized, the optimized TLMC can better balance the focality and stimulation depth.