A Compact Triaxial SERF Magnetometer With High Sensitivity and 1.1 kHz Bandwidth for Magnetoencephalography

Miniaturized spin-exchange relaxation-free (SERF) magnetometers are recognized for their exceptional sensitivity and ability to function without the need for cryogenic cooling. These devices are particularly valuable for detecting ultra-weak magnetic fields, such as those generated by the human brain. However, the use of miniaturized SERF magnetometers has been limited due to their narrow bandwidth. In this study, we developed a compact triaxial SERF magnetometer that incorporates closed-loop feedback, significantly broadening its bandwidth to 1.1 kHz. This magnetometer achieves high sensitivity, approximately 35 fT/(Hz)1/2 across each axis and remains compact, with dimensions of
$13.8\times 21.0\times 44.0$
mm. It accurately measured the time course of pulsed sinusoidal magnetic fields, with each pulse containing a single cycle of a 1030 Hz sinusoidal signal at a 1 pT amplitude. Our magnetometer also successfully detected various magnetic fields generated by the human brain, including alpha rhythms, auditory evoked fields (AEFs), and steady-state visual evoked fields. Looking forward, this high-bandwidth, high-sensitivity, and compact triaxial SERF magnetometer showcases its great potential for advancing magnetoencephalography (MEG) and opening new research avenues in neuroscience and clinical research.