Simultaneous measurements of magnetomyographic and magnetocardiographic signals using SQUIDs and relocatable magnetoresistive-device-based flux sensors

Biomagnetic field measurement is effective for the noninvasive investigation of electrical activities in a living body. Recent advancements in room-temperature (RT) magnetic sensors, such as magnetoresistance (MR) devices, have enabled their use in detecting weak magnetic fields from the body surface, which were earlier detectable only with superconducting interference device (SQUID) magnetic sensors. Although MR-based flux sensors (MR sensors) have inferior magnetic field resolution compared to SQUID sensors, they offer high flexibility for sensor placement. In this study, a relocatable MR sensor array was applied to detect biomagnetic signals alongside a conventional 132-ch SQUID-based sensor array for magnetoneurography to simultaneously record biomagnetic signals, such as magnetomyographic or magnetocardiographic signals. The results indicated that both sensor systems could successfully detect the significant biomagnetic signals with negligible interference between them.