https://doi.org/10.1140/epjqt/s40507-020-00086-4
Research
A conformal array of microfabricated optically-pumped first-order gradiometers for magnetoencephalography
1
University of Colorado Boulder, Boulder, CO, 80309, USA
2
FieldLine Inc., Boulder, CO, 80301, USA
* e-mail: svenja.knappe@colorado.edu
Received:
4
June
2020
Accepted:
31
August
2020
Published online:
11
September
2020
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.
Key words: Magnetometer / Atomic / Laser sensors / Quantum sensors / Optical instruments / Micro-optical devices / Spin-exchange relaxation-free (SERF) / Magnetoencephalography (MEG) / Optically-pumped magnetometer (OPM)
© The Author(s), 2020
