Residual field suppression for magnetocardiography measurement inside a thin magnetically shielded room using bi-planar coil

• Published in: Chinese physics B Vol. 31; no. 7; pp. 70701 - 263
• Main Authors: Yang, Kang, Zhang, Hong-Wei, Zhang, Qian-Nian, Zha, Jun-Jun, Huang, Deng-Chao
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.06.2022; College of Electrical Engineering,Anhui Polytechnic University,Wuhu 241000,China; Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment,Ministry of Education,Anhui Polytechnic University,Wuhu 241000,China
• Subjects: active compensation; bi-planar coil; magnetocardiography; SQUID; bi-planar coil; SQUID; magnetocardiography; active compensation
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ac6163

For a magnetocardiography (MCG) system inside a magnetically shielded room (MSR), the residual field should be further suppressed to obtain high-quality MCG signals. In this paper, a compensation system has been developed based on the bi-planar coil and the proportional-integral-derivative (PID) controller. The bi-planar coil, derived from the target-field theory and the Tikhonov regularization method, is utilized to generate magnetic field with high uniformity in the pre-defined target region. And the PID controller is introduced to provide dynamic compensation current for the coil, according to the residual field change monitored by a reference SQUID magnetometer. The measurement results show that the noise suppression ratio (NSR) can reach above 20 dB in the low-frequency range from 0.1 Hz to 50 Hz. The DC component and the fluctuation of the residual field in time-domain can be respectively suppressed to 0 pT and 4 pT, indicating that this proposed compensation method is useful for the MCG measurement.