Air-core Coil Gradiometer for Biomagnetic Sensing in Non-shielded Environments

Magnetic fields emitted from the human body can serve as indicators of diverse health conditions. However, such fields are very small, making it hard to detect. Devices used to date for capturing these fields are bulky, expensive, and require additional equipment such as heaters, coolers, lasers, and/or shielding rooms. In this work, we report a lightweight miniature air-core coil gradiometer that is combined with advanced Digital Signal Processing (DSP) to capture biomagnetic fields in non-shielded environments. In vitro experimental results show that our gradiometer can pick up 50-Hz signals as low as 76 fT by averaging 5 min of raw data. Notably, the gradiometer's coil has an outer diameter of only 14.5 mm, height of 10 mm and weight of 1.64 g. In the future, this design can be modified to detect in vivo biomagnetic signals including: magnetomyography (MMG), magnetocardiography (MCG), magnetoencephalography (MEG), and magnetospinography (MSG).