The Calculation of Maximum Electric Field Intensity in Brain Tissue Stimulated by a Current Pulse through a Microcoil via Capacitive Coupling

Abstract

The purpose of this paper is to calculate the maximum electric field in the brain tissue surrounding a microcoil. The microcoil is represented as a wire coupled capacitively to the surrounding tissue. For a 1 mA, 3 kHz current in the wire, the value of the electric field intensity in the tissue is approximately 4 mV/m. The intensity of the electric field is proportional to the frequency, the capacitance per unit area, and the square of the wire length. The electric field produced by this coil by electromagnetic induction is in the order of 0.002 mV/m. Therefore, the electric field produced by capacitive coupling is much greater than the electric field produced by induction. Methods to distinguish between capacitive and magnetic stimulation are discussed.