Electronic gradiometer in cylindrical magnetic shield for compact magnetocardiograph

Abstract

An electronic first-order gradiometer in a cylindrical magnetic shield was investigated in order to determine the best magnetometer configuration for a compact multichannel magnetocardiograph (MCG). It was found that a planar gradiometer is better in terms of noise reduction than an axial gradiometer. This is because the magnetic field inside the cylindrical magnetic shield exhibits an anisotropic distribution, which was confirmed by a numerical calculation using a three-dimensional finite element method. It was also found that MCG measurement in the cylindrical magnetic shield is possible by using a planar electronic gradiometer with high-Tc directly coupled magnetometers. This configuration can successfully detect the P-wave in MCG signal without the need for averaging.