Coil optimization for magnetic brain stimulation.

Further development of magnetic brain stimulation requires smaller coils, smaller power consumption, and less coil heating. This study addresses the optimization of the complete stimulator and in particular the coil. We describe the coil structure in terms of simple mathematical functions and examine the influence of changes in the structure on several figures of merit. A few optimal coil geometries suitable for repetitive brain stimulation are depicted. It is demonstrated that today's coils are far from optimal and that, for instance, the power consumption can be reduced remarkably from the level of today's equipment. Improvements may act as a springboard toward new applications.