A vector magnetometer module for biomagnetic application

Multichannel SQUID systems are widely used for biomagnetic research. Commonly, these instruments measure one component of the magnetic vector field or one gradient of vector field. We have designed a vector magnetometer module allowing the recording of orthogonal vector components. The module is designed as a cube with one liquid helium cooled SQUID mounted at each of its six faces. The mean values of signals from SQUIDs of opposite faces are estimates for the magnetic field components in the center of the cube. Due to Maxwell's third equation, the signals of the six SQUIDs can be combined to yield zero. This allows an on-line check of the SQUID performance. The features of the vector magnetometer module are illustrated by cardiac measurements. 3D graphics allow direct inspection of the magnetic field vector. The cube is designed to be used as a basic module of a multichannel SQUID system for biomagnetic application.