Characterization of magnetic flux density in passive sources used in magnetic stimulation

The spatial distribution of the magnetic flux density (B) was determined for the passive sources of magnetic field most used in magnetic stimulation of biological systems, toroidal dipole magnets and cylindrical dipole magnets, in order to find the spatial characteristics of the magnetic field within the volumes of interest for the treatment of biological systems. The perpendicular and parallel components of B regarding the polar surface of the magnets were measured, for which a FW Bell 5180 digital teslameter was used with longitudinal and transverse probes and a two-dimensional positioning system with millimeter scale. It was found that the magnets of this type, which are the most used, present a strong variation of the magnitude and direction of the magnetic flux density for spaces specified in millimeters, reason why the homogeneity of the magnetic field in the regions of interest was found to be relatively low, which makes them elements with a strong applicability for the stimulation of biological systems in which magnetic field gradients up to mT/mm are required in the case of cylindrical magnets, and up to tens of mT/mm in the case of toroidal magnets. Finally, it is concluded that a high percentage of experiments reported in the literature on magnetic treatment of biological systems may be presenting values of B in their doses with deviations of more than 100% of the real value, which raises an incongruence in the cause-effect proposed relation.