Design of a miniaturized forearm magnetomyography detection system based on biplanar coils

Magnetomyography (MMG) is a precise method for assessing muscle conditions, particularly when measured with high-sensitivity optically pumped magnetometers. However, the MMG signal amplitude, typically on the order of pico-Tesla (pT), is susceptible to interference from the geomagnetic field. Traditional shielding systems, which are effective in mitigating this interference, are nonetheless bulky and occupy considerable space, thereby limiting their portability and hindering their widespread application. In this study, we propose a compensation system for a compact forearm-based MMG detection device utilizing biplanar coils. This system effectively addresses the challenges posed by uneven and excessive residual magnetic fields within the miniaturized device, achieving up to a 91.9% reduction in residual magnetic fields from multiple directions. Using this enhanced device, MMG signals are detected from the forearms of a subject under various grip strengths. Time-domain analyses of these signals provide valuable insights into grip strength.