Biomedical magnetic induction tomography using two-arm Archimedean spiral coil: A feasibility study

Based on the principle of primary excitation magnetic field counteraction, in this paper a new type of excitation coil named two-arm Archimedean spiral coil (TAASC) is designed and first introduced into biomedical magnetic induction tomography coil system to improve the coil system sensitivity. The primary voltage and the scaled level map of secondary voltage perturbation for the TAASC are calculated through theory and simulation. The coil system sensitivity curves when using the TAASC as excitation coil are tested at different positions, electrical conductivities and frequencies by simulation experiments. As a control, all the theoretical calculations and simulation experiments are conducted again for the circular excitation coil. The results show that the primary excitation magnetic field can be markedly counteracted while the secondary induction magnetic field perturbation is nearly at the same order of magnitude, and the coil system has a bigger sensitivity with an improvement factor of 10³ to 10⁴ by using this new type of TAASC as excitation coil, compared with the common circular excitation coil. The simulated results are in good agreement with the theoretical results.