Avoiding non-linearity of optically pumped magnetometer MEG within an actively shielded two-layer mu-metal room

Tilmann H. Sander, Urban Marhl, Vojko Jazbinšek
2021 Current Directions in Biomedical Engineering  
Some optically pumped magnetometer (OPM) sensors available for biomagnetic investigations have a linear range limited to +- 1 nT due to the specific properties of their open loop operation. In a two-layer magnetically shielded room of type Ak3b/Vacoshield Advanced with an external active compensation we studied how much sensor movement is allowed until amplitudes exceed the linearity range. Intentional movements were performed by a subject wearing an OPM-MEG sensor array. It was found that
more » ... ents of 8 cm did yield non-linear amplitudes, but a reduction of the movement in half already preserves linearity. Despite movements, the heartbeat was found to generate a periodic signal, although the generating mechanism could not be identified so far.
doi:10.1515/cdbme-2021-2138 fatcat:bgoyj7ftxrf4blqlajsbiggsia