Cross-Axis projection error in optically pumped magnetometers and its implication for magnetoencephalography systems

Borna, Amir; Iivanainen, Joonas; Carter, Tony R.; McKay, Jim; Taulu, Samu; Stephen, Julia M.; Schwindt, Peter D. D.

doi:10.1016/j.neuroimage.2021.118818

Cited by 69 publications

(56 citation statements)

References 28 publications

(46 reference statements)

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“…The main challenge of localized field control is to operate multiple field-feedback loops without introducing cross talk. Here, the source of cross talk is where a time-dependent compensatory field at one OPM sensor is non-compensatory at its neighbors, and may significantly alter the measured magnetic field component 18 . At this point the stray fields produced between neighboring OPMs become of concern and indeed may be considered the dominant source of error in the response.…”

Section: B Field Control For Zero-field Opms Used In Megmentioning

confidence: 99%

“…It is also advantageous to minimize stray fields when two or more sensor units are used in close proximity to one another. In the case of OPMs, a reduced stray field minimizes cross talk and improves sensor dynamic range 16,17 , and also ensures a linear, well-defined sensor readout 18 . Together these requirements define a design goal for magnetic coils, which must be met by mass-manufacturing techniques.…”

Section: Introductionmentioning

confidence: 99%

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Miniature biplanar coils for alkali-metal-vapor magnetometry

Tayler,

Mouloudakis,

Zetter

et al. 2022

Preprint

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Atomic spin sensors offer precision measurements using compact, microfabricated packages, placing them in a competitive position for both market and research applications. Performance of these sensors such as dynamic range may be enhanced through magnetic field control. In this work, we discuss the design of miniature coils for three-dimensional, localized field control by direct placement around the sensor, as a flexible and compact alternative to global approaches used previously. Coils are designed on biplanar surfaces using a stream-function approach and then fabricated using standard printedcircuit techniques. Application to a laboratory-scale optically pumped magnetometer of sensitivity ∼20 fT/ √ Hz is shown. We also demonstrate the performance of a coil set measuring 7 × 17 × 17 mm 3 that is optimized specifically for magnetoencephalography, where multiple sensors are operated in proximity to one another. Characterization of the field profile using 87 Rb free-induction spectroscopy and other techniques show >96% field homogeneity over the target volume of a MEMS vapor cell and a compact stray field contour of ∼1% at 20 mm from the center of the cell.

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Section: B Field Control For Zero-field Opms Used In Megmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Miniature biplanar coils for alkali-metal-vapor magnetometry

Tayler,

Mouloudakis,

Zetter

et al. 2022

Preprint

View full text Add to dashboard Cite

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“…Superconducting quantum interferometer device (SQUID) is usually used for direct measurement of cardiac magnetic field and brain magnetic field signals [82], but its application is greatly limited by the high maintenance cost and liquid helium Dewar bottle of superconducting refrigeration [83,84]. Fortunately, the SERF atomic magnetometer can realize ultra-high precision magnetic field measurement, and has the advantages of no need for low-temperature cooling, wearable human body and mobile measurement, which makes it greatly developed in the field of biological magnetic field detection such as human cardiac magnetism and brain magnetism [9,10].…”

Section: Biomedicinementioning

confidence: 99%

“…They studied the auditory evoked magnetic field and somatosensory evoked magnetic field and cross-verified with the SQUID-based brain magnetic mapping system to achieve sub-centimeter precision magnetic source positioning, which provided the possibility for the MEG system with full head coverage of a compatible and flexible OPM sensor array [99, 100], as shown in Figure 17. The group also discussed the influence of horizontal axis projection error on the positioning and calibration accuracy of MEG system [10].…”

Section: Biomedicinementioning

confidence: 99%

“…Quantum precision magnetic field measurement is of great value in the fields of electric dipole moment (EDM) measurement in Frontier physics research [5], brain magnetic and cardiac magnetic field measurement in brain science and medicine [9,10], deep space magnetic field exploration in space science [11], etc. Quantum inertial measurement has broad application prospects in Frontier physics research such as Charge conjugation-Parity transformation-Time reversal (CPT) conservation [12,13] and long-time high-precision navigation of moving vehicles [14].…”

Section: Introductionmentioning

confidence: 99%

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Progress and applications of quantum precision measurement based on SERF effect

Zhai

Yue²,

Li³

et al. 2022

Front. Phys.

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With the development of quantum precision measurement technology, measurement methods based on magnetic, optical and atomic interactions have started to receive widespread attention. Among them, quantum precision measurement based on the spin-exchange relaxation-free (SERF) effect shows great potential by its ultra-high measurement sensitivity. This paper introduces the basic operation principles of the magnetic field and inertia measurement based on the SERF effect, and focuses on the research progress and applications of SERF quantum precision measurement in fundamental physics, inertial navigation and biomedicine. Finally, we propose a prospect for the directions of SERF quantum precision measurement.

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Adaptive multipole models of optically pumped magnetometer data

Tierney,

Seedat,

St Pier

et al. 2024

Human Brain Mapping

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Multipole expansions have been used extensively in the Magnetoencephalography (MEG) literature for mitigating environmental interference and modelling brain signal. However, their application to Optically Pumped Magnetometer (OPM) data is challenging due to the wide variety of existing OPM sensor and array designs. We therefore explore how such multipole models can be adapted to provide stable models of brain signal and interference across OPM systems. Firstly, we demonstrate how prolate spheroidal (rather than spherical) harmonics can provide a compact representation of brain signal when sampling on the scalp surface with as few as 100 channels. We then introduce a type of orthogonal projection incorporating this basis set. The Adaptive Multipole Models (AMM), which provides robust interference rejection across systems, even in the presence of spatially structured nonlinearity errors (shielding factor is the reciprocal of the maximum fractional nonlinearity error). Furthermore, this projection is always stable, as it is an orthogonal projection, and will only ever decrease the white noise in the data. However, for array designs that are suboptimal for spatially separating brain signal and interference, this method can remove brain signal components. We contrast these properties with the more typically used multipole expansion, Signal Space Separation (SSS), which never reduces brain signal amplitude but is less robust to the effect of sensor nonlinearity errors on interference rejection and can increase noise in the data if the system is sub‐optimally designed (as it is an oblique projection). We conclude with an empirical example utilizing AMM to maximize signal to noise ratio (SNR) for the stimulus locked neuronal response to a flickering visual checkerboard in a 128‐channel OPM system and demonstrate up to 40 dB software shielding in real data.

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Cross-Axis projection error in optically pumped magnetometers and its implication for magnetoencephalography systems

Cited by 69 publications

References 28 publications

Miniature biplanar coils for alkali-metal-vapor magnetometry

Miniature biplanar coils for alkali-metal-vapor magnetometry

Progress and applications of quantum precision measurement based on SERF effect

Adaptive multipole models of optically pumped magnetometer data

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