Calculation of induced electric fields by duality

Considers the prediction of induced electric fields for nerve stimulation. Although functional electric stimulators have been in existence for many years, functional (site specific) magnetic stimulation is virgin territory. The problem of predicting localized electric fields from potential magnetic stimulators falls into a special class of eddy current problems. In this class, the currents do not themselves effect the primary magnetic field responsible for the induced current; the medium conductivity is far too small for this secondary coupling. A two stage static magnetic analysis is used to compute the induced electric fields accurately for a number of problems falling within this category. The computations accurately reflect the influence of conductivity jumps at interfaces, induced charges, and voltages between points, but use conventional magnetic scalar potential boundary element solvers. The problems are solved as if they were magneto-quasistatic using duality. Comparisons to experiment validate the accuracy of this technique. The analysis is addressed to the induced bioelectric fields during magnetic simulation, but the theory applies equally well to any problem where the induced eddy current has little bearing on the field because of its small amplitude