A synthetic optically pumped gradiometer for magnetocardiography measurements

doi:10.1088/1674-1056/ab7801

Abstract Magnetocardiography (MCG) measurement is important for investigating the cardiac biological activities. Traditionally, the extremely weak MCG signal was detected by using superconducting quantum interference devices (SQUIDs). As a room-temperature magnetic-field sensor, optically pumped magnetometer (OPM) has shown to have comparable sensitivity to that of SQUIDs, which is very suitable for biomagnetic measurements. In this paper, a synthetic gradiometer was constructed by using two OPMs under spin-exchange relaxation-free (SERF) conditions within a moderate magnetically shielded room (MSR). The magnetic noise of the OPM was measured to less than 70 fT/Hz^1/2. Under a baseline of 100 mm, noise cancellation of about 30 dB was achieved. MCG was successfully measured with a signal to noise ratio (SNR) of about 37 dB. The synthetic gradiometer technique was very effective to suppress the residual environmental fields, demonstrating the OPM gradiometer technique for highly cost-effective biomagnetic measurements.

Keywords: optically pumped magnetometer (OPM) magnetocardiography (MCG) gradiometer

Received: 13 December 2019
Revised: 08 February 2020
Accepted manuscript online:

PACS:	07.07.Df	(Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing)
	87.85.Ox	(Biomedical instrumentation and micro-electro-mechanical systems (MEMS))
	07.55.Ge	(Magnetometers for magnetic field measurements)

Fund: Project supported by the National Natural Science Foundation of China (Grant No. 61701486).

Corresponding Authors: Shu-Lin Zhang
E-mail: zhangsl@mail.sim.ac.cn

Cite this article:

Shu-Lin Zhang(张树林), Ning Cao(曹宁) A synthetic optically pumped gradiometer for magnetocardiography measurements 2020 Chin. Phys. B 29 040702

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