Toroidal coil models for transcutaneous magnetic stimulation of nerves

A novel design of coils for transcutaneous magnetic stimulation of nerves i s presented, These coils consist of a toroidal winding around a high-permea bility material (Supermendur) tore embedded in a conducting medium, Theoret ical numerical calculations are used to analyze the effect of the design pa rameters of these coils, such as coil width, toroidal radius, conducting la yer thickness and core transversal shape on the induced electric fields in terms of the electric field strength and distribution. Results indicate tha t stimulation of nerves with these coils has some of the advantages of both electrical and magnetic stimulation. These coils can produce localized and efficient stimulation of nerves with induced electric fields parallel and perpendicular to the skin similar to surface electrical stimulation, Howeve r, they retain some of the advantages of magnetic stimulation such as no ri sk of tissue damage due to electrochemical reactions at the electrode inter face and less uncomfortable sensations or pain. The driving current is redu ced by over three orders of magnitude compared to traditional magnetic stim ulation, eliminating the problem of coil heating and allowing for long dura tion and high-frequency magnetic stimulation with inexpensive stimulators.