Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland.
Sensors (Basel). 2020 Aug 14;20(16):4563. doi: 10.3390/s20164563.
Magnetography with superconducting quantum interference device (SQUID) sensor arrays is a well-established technique for measuring subtle magnetic fields generated by physiological phenomena in the human body. Unfortunately, the SQUID-based systems have some limitations related to the need to cool them down with liquid helium. The room-temperature alternatives for SQUIDs are optically pumped magnetometers (OPM) operating in spin exchange relaxation-free (SERF) regime, which require a very low ambient magnetic field. The most common two-layer magnetically shielded rooms (MSR) with residual magnetic field of 50 nT may not be sufficiently magnetically attenuated and additional compensation of external magnetic field is required. A cost-efficient compensation system based on square Helmholtz coils was designed and successfully used for preliminary measurements with commercially available zero-field OPM. The presented setup can reduce the static ambient magnetic field inside a magnetically shielded room, which improves the usability of OPMs by providing a proper environment for them to operate, independent of initial conditions in MSR.
超导量子干涉仪（SQUID）传感器阵列的磁强计是一种成熟的技术，用于测量人体生理现象产生的微弱磁场。不幸的是，基于 SQUID 的系统有一些与需要用液氦冷却相关的限制。SQUID 的室温替代品是在自旋交换弛豫自由（SERF）状态下工作的光泵磁强计（OPM），它需要非常低的环境磁场。最常见的两层磁屏蔽室（MSR）的残余磁场为 50 nT，可能不会被充分衰减，需要对外磁场进行额外补偿。设计了一种基于方形亥姆霍兹线圈的经济高效的补偿系统，并成功地用于具有商业可用性的零场 OPM 的初步测量。所提出的设置可以降低磁屏蔽室内的静态环境磁场，这通过为 OPM 提供适当的工作环境来提高它们的可用性，而与 MSR 中的初始条件无关。
