Optical Magnetometer Array for Fetal Magnetocardiography

TL;DR

This paper presents a novel array of optical magnetometers designed for fetal magnetocardiography, demonstrating the first measurements of fetal heart signals using atomic magnetometers with gradiometry for noise reduction.

Contribution

Introduction of a compact optical magnetometer array capable of detecting fetal heart signals with noise cancellation techniques.

Findings

First measurement of fetal magnetocardiography with atomic magnetometers

Array configuration enables effective noise suppression

Potential for non-invasive fetal heart monitoring

Abstract

We describe an array of spin-exchange relaxation free optical magnetometers designed for detection of fetal magnetocardiography (fMCG) signals. The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. Using this array, we present the first measurements of fMCG signals using an atomic magnetometer.