An array of 21 first-order gradiometers based on zero-field optically-pumped magnetometers is demonstrated for use in magnetoencephalography. Sensors are oriented radially with respect to the head and housed in a helmet with moveable holders which conform to the shape of a scalp. Our axial gradiometers have a baseline of 2 cm and reject laser and vibrational noise as well as common-mode environmental magnetic noise. The median sensitivity of the array is 15.4 fT/Hz1/2, measured in a human-sized magnetic shield. All magnetometers are operated independently with negative feedback to maintain atoms at zero magnetic field. This yields higher signal linearity and operating range than open-loop operation and a measurement system that is less sensitive to systematic and ambient magnetic fields. All of the system electronics and lasers are compacted into one equipment rack which offers a favorable outlook for use in clinical settings.
CITATION STYLE
Nardelli, N. V., Perry, A. R., Krzyzewski, S. P., & Knappe, S. A. (2020). A conformal array of microfabricated optically-pumped first-order gradiometers for magnetoencephalography. EPJ Quantum Technology, 7(1). https://doi.org/10.1140/epjqt/s40507-020-00086-4
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