Magnetoencephalography (MEG) uses extremely sensitive magnetometers such as SQUIDs (superconducting quantum interference devices) or OPMs (optically pumped magnetometers) to record very small magnetic fields induced by synchronized ionic nerve currents in the brain.
MEG records data instantaneously so that a wide range of neurological brain processes can be effectively observed and studied in real time. from mapping brain responses to stimuli to studying structural abnormalities in the brain.
While MEG is valuable for a wide range of noninvasive neurological research, it is also widely used in conjunction with other forms of imaging such as positron emission tomography (PET) and electroencephalography (EEG).
The ambient geomagnetic field is approximately 50 μT; the field generated by the brain is on the order of 10 to 9 μT (or 1 fT).The need to shield oneself from the much larger ambient field is clearly evident in order to obtain useful measurement results of these small fields.Field signals of no interest must be removed, which can be done with an appropriately designed magnetic shield. There are usually numerous applications for small shields, based on the principle that a highly permeable material redirects the field around the volume of interest, making that volume virtually field-free.
If we were to simply scale a small shield to the dimensions of a room with large flat surfaces, we would see a significant decrease in the efficiency of the shield. The increasing demand for large, magnetically shielded volumes with high field attenuation, has led us to develop optimally shielded rooms, consisting of several MUMETAL® layers as well as copper or aluminum layers, for shielding RF fields, which achieve remarkable shielding factors.
MUMETAL® is a registered trademark of Carpenter Technology (UK) Limited