Influence of coil geometry on localization of the induced electric field in magnetic (eddy-current) stimulation of excitable tissue

• Published in: IEEE transactions on magnetics 1990-09, Vol.26 (5), p.1545-1547
• Main Authors: Mouchawar, G.A., Nyenhuis, J.A., Bourland, J.D., Geddes, L.A.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biomedical engineering; Coils; Conductors; Current density; Eddy currents; Effects of various physical factors on living matter (vibrations, electric field, ultrasound, sound...); Electrostatics; Fundamental and applied biological sciences. Psychology; Geometry; Magnetic fields; Magnetic stimulation; Permittivity; Tissues, organs and organisms biophysics
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/20.104439

Magnetic stimulation is the process of stimulating excitable tissue with an electric field which is induced by a time-varying intense magnetic field. Calculations were performed to investigate the effect of coil geometry on localization of the induced electric field. The calculations considered a pair of coplanar coils parallel to a planar conducting medium that represents the stimulated tissue and a coil on edge. These two coil geometries give similar localization in a plane that is parallel to the interface, and the best localization is obtained for a coil radius that is small compared to the target depth. A drawback of the small coil is that the field at the target site is much less than the field at the surface of the conductor. A good three-dimensional localization is obtained with a pair of coplanar coils having radii approximately twice the target depth.< >