Influence of Motion Artifacts on the Performance of Optically Pumped Magnetometers and Accuracy of Magnetoencephalography Source Localization

In this paper, the relationship between motion artifacts and magnetoencephalogram (MEG) source localization errors was established for the MEG system based on array optically pumped magnetometers (OPM). The influences of bias fields on OPM’s performances were first evaluated through theoretical and experimental analysis, whose results proved that the bias magnetic fields along the sensitive axis affect the gain and sensitivity of OPM, while the pumping axis bias magnetic fields affect the direction of the sensitive axis. The OPM with a large linewidth has better anti-interference ability but worse sensitivity. Then, MEG simulations were carried out on the basis of OPM performance testing. The relative error of the forward model proved that the rotated sensitive axis would affect the forward model, while the gain error and sensitivity directly affect the signal-to-noise ratio of the MEG signal. The experiment and simulation also proved that it is recommended to use biaxial mode for OPM-MEG experiments and the motion artifact detected by OPMs should be reduced to less than 1nT at least. Moreover, the linewidth of the OPM’s cell is positively correlated with the anti-interference capability of OPM. Therefore, sensitivity and anti-interference capability must be simultaneously considered in the design of OPM by optimizing the cell’s linewidth to adapt to more scenarios.