Brain magnetic field measurement: Novel techniques and applications

Abstract

This study reviews recent advancements in brain magnetic field measurement, focusing on fundamental principles and clinical implications. Magnetoencephalography（MEG）, a noninvasive brain imaging technique, offers unparalleled spatiotemporal resolution. However, the current gold standard device used for MEG, the superconducting quantum interference device（SQUID）, is large/bulky, costly, and depends on cryogenic cooling systems, limiting its accessibility. Moreover, it is highly sensitive to environmental magnetic noise, particularly the geomagnetic field, hindering the full potential of MEG. In recent years, inexpensive, compact, and highly sensitive magnetic sensors that can operate at room temperature, such as optically pumped magnetometers（OPMs）and tunnel magnetoresistance（TMR）sensors, have emerged as promising alternatives. TMR sensors, a unique technology pioneered by Tohoku University in Japan, offer an extended magnetic field measurement range compared to conventional methods. The practical application of these next-generation magnetic sensors will expand the scope of MEG applications beyond fundamental studies on human brain function. Potential medical applications include the precise identification of epileptic foci and advancements in brain-machine interfaces.departmental bulletin pape