Improved Biomagnetic Signal-To-Noise Ratio and Source Localization Using Optically Pumped Magnetometers with Synthetic Gradiometers

Jing Xiang, Xiaoqian Yu, Scott Bonnette, Manish Anand, Christopher D. Riehm, Bryan Schlink, Jed A. Diekfuss, Gregory D. Myer, Yang Jiang

Research output: Contribution to journalArticlepeer-review


Optically pumped magnetometers (OPMs) can capture brain activity but are susceptible to magnetic noise. The objective of this study was to evaluate a novel methodology used to reduce magnetic noise in OPM measurements. A portable magnetoencephalography (MEG) prototype was developed with OPMs. The OPMs were divided into primary sensors and reference sensors. For each primary sensor, a synthetic gradiometer (SG) was constructed by computing a secondary sensor that simulated noise with signals from the reference sensors. MEG data from a phantom with known source signals and six human participants were used to assess the efficacy of the SGs. Magnetic noise in the OPM data appeared predominantly in a low frequency range (<4 Hz) and varied among OPMs. The SGs significantly reduced magnetic noise (p < 0.01), enhanced the signal-to-noise ratio (SNR) (p < 0.001) and improved the accuracy of source localization (p < 0.02). The SGs precisely revealed movement-evoked magnetic fields in MEG data recorded from human participants. SGs provided an effective method to enhance SNR and improve the accuracy of source localization by suppressing noise. Software-simulated SGs may provide new opportunities regarding the use of OPM measurements in various clinical and research applications, especially those in which movement is relevant.

Original languageEnglish
Article number663
JournalBrain Sciences
Issue number4
StatePublished - Apr 2023

Bibliographical note

Funding Information:
The project described was supported by the United States National Institutes of Health (NIH) Grant Number R21 NS104459 from the National Institute of Neurological Disorders and Stroke (NINDS). The normative database used in the present study was partially supported by Grant Number R21NS081420 and R21NS072817 from NIH/NINDS. The project described was partially supported by funding from NIH/National Institute of Aging (NIA) 1R56AG060608, the State of Ohio, Ohio Development Services Agency, Ohio Third Frontier, Grant Control No. TECG20170361 and TECG20190159.

Publisher Copyright:
© 2023 by the authors.


  • magnetoencephalography
  • noise cancellation
  • optically pumped magnetometer
  • signal-to-noise ratio
  • synthetic gradiometer
  • wearable MEG

ASJC Scopus subject areas

  • Neuroscience (all)


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