Atomic Magnetometry for Biomedical Applications

Atomic magnetometry exploits the interaction between atomic spins and magnetic fields to achieve extraordinarily sensitive measurement of biomagnetic signals. In these devices, vapours of alkali atoms such as rubidium or cesium are optically pumped into a spin-polarised state and subsequently interrogated by laser light. Changes in atomic spin precession induced by external magnetic fields are detected via optical readout, yielding sensitivities that rival cryogenic superconducting sensors without the need for cryogenic cooling. Advances in microfabrication have enabled chip-scale vapour cells and integrated photonics, paving the way for miniaturised, portable instruments. Operating in regimes such as the spin-exchange relaxation-free (SERF) limit further suppresses noise, achieving femtotesla-level sensitivity. These attributes make atomic magnetometers particularly well suited to biomedical applications including magnetoencephalography (MEG), magnetocardiography (MCG) and magnetoneurography, where non-invasive detection of minute magnetic fields generated by neural or cardiac activity is required. Recent progress in helmet-mounted arrays, dynamic background-field control and wearable form factors has opened new opportunities for naturalistic studies of brain function, bedside monitoring and point-of-care diagnostics.

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Atomic Magnetometry for Biomedical Applications publication trend

The graph below shows the total number of articles in atomic magnetometry for biomedical applications across all publications each year (not limited to Nature Index journals).

Technical terms

Optically Pumped Magnetometer (OPM): A sensor that polarises atomic spins by resonant laser light and measures spin precession induced by external magnetic fields via optical detection.

Spin-Exchange Relaxation-Free (SERF) Regime: A high-density atomic vapour regime in which rapid spin-exchange collisions average out decoherence, yielding ultrahigh magnetic sensitivity.

Magnetoencephalography (MEG): A neuroimaging technique that records magnetic fields produced by neuronal currents, enabling non-invasive functional mapping of the brain.

Bi-planar Coil System: An arrangement of paired flat coils used to generate uniform magnetic fields or gradients for active nulling of background interference in shielded environments.

Equivalent Current Dipole (ECD): A simplified mathematical model representing the net neuronal current source, used to localise brain activity from measured magnetic fields.

References

1. A new generation of magnetoencephalography: Room temperature measurements using optically-pumped magnetometers. NeuroImage (2017).
2. Optically pumped magnetometers: From quantum origins to multi-channel magnetoencephalography. NeuroImage (2019).
3. Chip-scale atomic devices. Applied Physics Reviews (2018).
4. Femtotesla atomic magnetometry in a microfabricated vapor cell.. Optics Express (2010).
5. Multi-channel whole-head OPM-MEG: Helmet design and a comparison with a conventional system. NeuroImage (2020).
6. A bi-planar coil system for nulling background magnetic fields in scalp mounted magnetoencephalography. NeuroImage (2018).
7. Balanced, bi-planar magnetic field and field gradient coils for field compensation in wearable magnetoencephalography. Scientific Reports (2019).
8. Ultrasensitive Magnetic Field Sensors for Biomedical Applications. Sensors (2020).