Using a single triangular coil to identify the position and orientation of the subject for biomagnetic measurements

Knowledge of the position and orientation of a subject in reference to an array of magnetic flux sensors is crucial for accurate current source reconstruction in biomagnetic field measurements. For alignment between the subject and the sensor array, multiple small circular marker coils, attached to anatomical fiducial points on the body's surface, are commonly used. We propose a new triangular marker coil that can replace the conventional marker coils. A triangular marker coil is effective for continuous positioning because, unlike conventional marker coils, it requires neither sequential excitation nor multiple oscillators. In this letter, a suitable design for triangular marker coils was investigated, and the positioning of an actual triangular marker coil using a magnetoencephalogram system was demonstrated.