Biomagnetic sensing: technologies and applications

<sec><p indent="0mm">Biomagnetic sensing technology allows for non-invasive monitoring and analysis of physiological activities within the human body by detecting and analyzing the weak magnetic fields generated by bioelectrical activities. These biomagnetic fields are universally present at both the cellular and organ levels, with the magnetic fields produced by the electrical activity of the heart and brain exhibiting distinct spatiotemporal distribution patterns. These patterns can provide valuable insights for clinical diagnosis and physiological research. </sec><sec> In this review, we begin by tracing the development of biomagnetic sensing technology, highlighting the evolution of techniques from induction coils and superconducting quantum interference devices (SQUIDs) to optically pumped magnetometers (OPMs). As the first-generation biomagnetic sensors, search coil technology was limited by its low sensitivity. SQUIDs, with their extremely high sensitivity, marked significant advances in the measurement of cardiac and brain magnetic fields. Nevertheless, their high cost and reliance on liquid helium restricted their widespread clinical applications. OPMs, the third-generation technology, offer high sensitivity without the need for liquid helium or nitrogen, and have emerged as a research hotspot in the field of biomagnetic sensing. Notably, recent advancements in unshielded OPM technology eliminate the need for expensive and bulky passive magnetically shielded devices, reducing costs and advancing the clinical application of biomagnetic sensing. </sec><sec> We then explore the applications of magnetocardiography (MCG) and magnetoencephalography (MEG), covering areas such as arrhythmias, coronary artery disease, fetal heart function evaluation, epilepsy, preoperative functional area localization, and brain-computer interfaces. Compared to traditional technologies like electrocardiography and electroencephalography, MCG and MEG reduce interference caused by variations in tissue conductivity, offering greater sensitivity for early disease diagnosis. Using source localization methods, MCG and MEG achieve submillimeter spatial resolution and millisecond temporal resolution, providing more precise spatiotemporal mapping of cardiac and brain electrical activity than traditional imaging technologies such as fMRI and PET. This enables more comprehensive electrophysiological data for both life sciences research and clinical diagnosis. </sec><sec> Furthermore, we discuss future trends in the development of this field from both technological and application perspectives. Technologically, the core of biomagnetic sensing systems—the magnetic sensor—is advancing along two main tracks: one focuses on optimizing performance to enhance detection sensitivity for subcellular-scale biomagnetic research, and the other prioritizes optimizing clinical applications, aiming to make the technology more suitable and cost-effective for medical monitoring and non-invasive diagnosis. In terms of application, the primary advantage of biomagnetic sensing technology lies in its high temporal and spatial resolution, which enables precise localization of organ function and dynamic visualization. Advances in unshielded OPM technology will allow biomagnetic sensing to adapt cost-effectively across multiple fields, promoting accurate diagnosis, advancing the analysis of physiological mechanisms, and fostering interdisciplinary innovation. </sec>