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Turning OPM-MEG into a Wearable Technology

Rhodes, Natalie; Holmes, Niall; Hill, Ryan; Barnes, Gareth; Bowtell, Richard; Brookes, Matthew; Boto, Elena

Authors

Natalie Rhodes

NIALL HOLMES NIALL.HOLMES@NOTTINGHAM.AC.UK
Mansfield Research Fellow

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RYAN HILL RYAN.HILL@NOTTINGHAM.AC.UK
Research Fellow

Gareth Barnes



Contributors

Etienne Labyt
Editor

Tilmann Sander
Editor

Ronald Wakai
Editor

Abstract

This chapter explores the use of optically pumped magnetometers (OPMs) as a tool for magnetoencephalography (MEG). Conventional MEG systems use superconducting quantum interference devices (SQUIDs) to measure the femto-Tesla-level magnetic fields at the head surface that are generated by synchronised (dendritic) neural current flow in the brain. SQUIDs require cryogenic cooling to maintain a low operating temperature and must be bathed in liquid helium and held in a rigid helmet with thermal insulation to protect the participant. Scanners are therefore large, cumbersome, and one-size-fits-all; movement of the participant relative to the fixed array degrades quality of data. Conversely, OPMs exploit the spin properties of alkali atoms to measure local magnetic field. They can be constructed with an external surface at close to body temperature, while maintaining a small, light, and flexible form. In this chapter, we show how commercial OPMs can form the basis of a MEG system that allows sensors to get closer to the scalp surface, improving signal strength and spatial specificity. Further, OPMs allow the flexibility to adapt a sensor array to any head shape or size and even facilitate natural movement throughout MEG acquisition. We explain why OPMs are emerging as a stand-out replacement for SQUIDs and how nascent sensor designs enable multi-axis measurements. We look at the practical requirements for designing sensor arrays that facilitate high spatial resolution imaging. We further describe how allowing movement requires additional background magnetic field suppression. Finally, we review recent literature to demonstrate how OPM-MEG has been used to enable novel neuroscientific experimentation.

Citation

Rhodes, N., Holmes, N., Hill, R., Barnes, G., Bowtell, R., Brookes, M., & Boto, E. (2022). Turning OPM-MEG into a Wearable Technology. In E. Labyt, T. Sander, & R. Wakai (Eds.), Flexible High Performance Magnetic Field Sensors: On-Scalp Magnetoencephalography and Other Applications (195-223). Springer International Publishing. https://doi.org/10.1007/978-3-031-05363-4_11

Acceptance Date Mar 24, 2022
Online Publication Date Aug 27, 2022
Publication Date Aug 27, 2022
Deposit Date Sep 14, 2022
Publicly Available Date Aug 28, 2024
Publisher Springer International Publishing
Pages 195-223
Book Title Flexible High Performance Magnetic Field Sensors: On-Scalp Magnetoencephalography and Other Applications
ISBN 9783031053627
DOI https://doi.org/10.1007/978-3-031-05363-4_11
Public URL https://nottingham-repository.worktribe.com/output/11195633
Publisher URL https://link.springer.com/chapter/10.1007/978-3-031-05363-4_11