Motion tolerance in wearable OPM-MEG using dynamic field nulling
- 1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
Abstract
Wearable magnetoencephalography (MEG) enabled by optically pumped magnetometers (OPMs) promises improved comfort and motion tolerance. This is particularly beneficial when measuring brain activity in children who cannot sit still for long periods of time. Compared to cryogenic MEG, wearable MEG allows larger head movements, but they result in artifacts due to uncompensated background fields and reduce source localization accuracy. Spatial filtering methods can partially compensate these motion-induced artifacts, but they are most effective when used in combination with background field nulling. This is because accurate spatial filtering relies on an accurate estimate of the sensor gain and orientation of its sensitive axis. Through simulations, we first deduce the target residual background field that is necessary for accurate dipole localization (< 1 cm) in the presence of head movements. Using our open-source printed circuit board (PCB) coils, we develop a method to dynamically null the background field. We demonstrate that our dynamic field nulling method allows improved localization of somatosensory evoked fields (SEFs) by maintaining the background field below the target residual fields established in the simulations. Our study highlights the importance of tracking both the background field and the head position relative to the background field for quality assurance in wearable MEG.
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BibTeX
@misc{jas2026motion,
title = {{Motion tolerance in wearable OPM-MEG using dynamic field nulling}},
author = {M. Jas and T. Matsubara and S. M. Stufflebeam and P. Sundaram and S. P. Ahlfors},
howpublished = {bioRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.17.745285},
url = {https://www.biorxiv.org/content/10.64898/2026.08.17.745285v2},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Motion tolerance in wearable OPM-MEG using dynamic field nulling
AU - M. Jas
AU - T. Matsubara
AU - S. M. Stufflebeam
AU - P. Sundaram
AU - S. P. Ahlfors
PY - 2026
DA - 2026/08/17
PB - bioRxiv
DO - 10.64898/2026.08.17.745285
UR - https://www.biorxiv.org/content/10.64898/2026.08.17.745285v2
AB - Wearable magnetoencephalography (MEG) enabled by optically pumped magnetometers (OPMs) promises improved comfort and motion tolerance. This is particularly beneficial when measuring brain activity in children who cannot sit still for long periods of time. Compared to cryogenic MEG, wearable MEG allows larger head movements, but they result in artifacts due to uncompensated background fields and reduce source localization accuracy. Spatial filtering methods can partially compensate these motion-induced artifacts, but they are most effective when used in combination with background field nulling. This is because accurate spatial filtering relies on an accurate estimate of the sensor gain and orientation of its sensitive axis. Through simulations, we first deduce the target residual background field that is necessary for accurate dipole localization (< 1 cm) in the presence of head movements. Using our open-source printed circuit board (PCB) coils, we develop a method to dynamically null the background field. We demonstrate that our dynamic field nulling method allows improved localization of somatosensory evoked fields (SEFs) by maintaining the background field below the target residual fields established in the simulations. Our study highlights the importance of tracking both the background field and the head position relative to the background field for quality assurance in wearable MEG.
ER -