Magnetocardiography with a modular spin-exchange relaxation-free atomic magnetometer array

Abstract

We present a portable four-channel atomic magnetometer array operating in the spin exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal magnetocardiography, such as a compact modular design and fibre coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6–11 fT Hz−1/2 single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.

Multi-sensor magnetoencephalography with atomic magnetometers

“…We therefore integrated coils onto each sensor vacuum housing sufficient for both field zeroing and field modulation. The field is zeroed by applying constant currents to three orthogonal coils following a well-documented procedure (Seltzer & Romalis 2004, Wyllie, Kauer, Smetana, Wakai & Walker 2012). Modulated fields at 1 kHz are applied to one the two sets of coils perpendicular to the optical axis.…”

“…MCG recordings with the CSAM have been cross-validated with SQUID recordings (Knappe et al 2010). A four-channel modular array of rubidium SERF AMs that measure the Faraday rotation of a probe beam due to an external field has successfully detected not only adult (Wyllie, Kauer, Smetana, Wakai & Walker 2012) but also fetal (Wyllie, Kauer, Wakai & Walker 2012) MCG signals.…”

Optically pumped alkali magnetometers for biomedical applications

“…More recently, MCG detection by chip-scale ODMR magnetometers was compared to SQUID-based detection in the high performance magnetic shielding room at PTB-Berlin [9]. Spin-exchange relaxation free magnetometers [3] have been applied for recording magneto-encephalographic signals [10], and have recently produced human [11] and fetal [12] MCG signals of outstanding quality.…”

Optical multichannel room temperature magnetic field imaging system for clinical application

“…The most sensitive optical magnetometers are even able to measure the weak signals of the human brain [12] and heart signals of an unborn child [13,14]. However, these magnetometers work in the spin-exchange relaxationfree (SERF) regime.…”