Real-Time Magnetocardiography with Passive Miniaturized Coil Array in Earth Ambient Field

We demonstrate a magnetocardiography (MCG) sensor that operates in non-shielded environments, in real-time, and without the need for an accompanying device to identify the cardiac cycles for averaging. We further validate the sensor's performance on human subjects. Our approach integrates seven (7) coils, previously optimized for maximum sensitivity, into a coil array. Based on Faraday's law, magnetic flux from the heart is translated into voltage across the coils. By leveraging digital signal processing (DSP), namely, bandpass filtering and averaging across coils, MCG can be retrieved in real-time. Our coil array can monitor real-time human MCG with clear QRS complexes in non-shielded environments. Intra- and inter-subject variability tests confirm repeatability and accuracy comparable to gold-standard electrocardiography (ECG), viz., a cardiac cycle detection accuracy of >99.13% and averaged R-R interval accuracy of <5.8 ms. Our results confirm the feasibility of real-time R-peak detection using the MCG sensor, as well as the ability to retrieve the full MCG spectrum as based upon the averaging of cycles identified via the MCG sensor itself. This work provides new insights into the development of accessible, miniaturized, safe, and low-cost MCG tools.

Automated summary

We demonstrate a real-time magnetocardiography (MCG) sensor that operates in non-shielded environments without an accompanying device for cardiac cycle identification. The sensor integrates optimized coils into an array to convert magnetic flux from the heart to voltage. By leveraging digital signal processing, MCG can be retrieved in real-time. The results confirm the feasibility of real-time R-peak detection and provide insights for the development of accessible, miniaturized, safe, and low-cost MCG tools.