An active magnetic compensative cardiomagnetic measurement system based on tunneling magnetic sensors

This study presents the successful development of an active magnetically compensative magnetocardiogram (MCG) detection system based on tunneling magnetic resistance (TMR) sensors. The active magnetic compensation system compensates for environmental magnetic noise in real-time using a three-axis coil, ultimately reducing the environmental static magnetic field to below 60 pT, with a shielding factor on the order of 10 6 . The system has a bandwidth of 10 kHz, allowing for the suppression of wideband AC magnetic disturbances, and achieves a background noise level on the order of 10 pT. The reliable MCG signals are successfully acquired and processed by a differential TMR sensor arrangement. The experimental results demonstrate that the MCG signals acquired using the tunneling magnetoresistance (TMR) sensor exhibit clearly identifiable QRS complexes, T waves, and P waves. These features show strong consistency with those observed in both the simultaneously recorded electrocardiogram (ECG) signals and the MCG signals obtained using optically pumped magnetometers (OPMs). In conclusion, the results of this experiment demonstrate the viability and efficacy of the MCG detection system based on TMR sensors, establishing a foundation for further research and applications of the cardiac magnetic signal.