Design of highly uniformity planar grid coils for obtaining near-zero magnetic field in magnetoencephalogram

Magnetoencephalography (MEG) based on optically pumped magnetometers has the ability to passively detect the extremely weak magnetic field signals, which is of crucial significance in the diagnosis and treatment of cerebral disorders. A highly uniform magnetic field produced by the uniform coil is required during the MEG measurement. In this paper, a novel design method for planar gird coil is proposed to obtain a high uniform magnetic field with a simpler coil structure. The finite element simulation results indicate that the space utilization ratio of the coils reaches 8% under the limit of 2% maximum inhomogeneity. The designed planar grid coils can achieve high homogeneity within a large uniform region, which is suitable for the active magnetic field compensation system to create a near-zero magnetic field environment during MEG measurement.