Development of a high spatial resolution SQUID magnetometer for biomagnetic measurement

Some high resolution superconducting quantum interference device (SQUID) magnetometers have been developed designed for nerves, muscles, slices of brain tissue and small animals. In these SQUID system, diameters of the pickup coil were a few millimeters and the distances between the pickup coil and the outside surface of the dewer were a few millimeters. We developed a super high resolution SQUID magnetometer for biomagnetic measurement having higher spatial resolution than previous systems. In this system, diameter of the pickup coil is 200/spl mu/m, the distance between the pickup coil and the outside surface of the dewar is 800/spl mu/m. The typical system noise in the magnetic shielded room is 2.7pT//spl radic/Hz in the frequency of the white-noise region. The spatial resolution of this SQUID system is analyzed using are demonstrated on a current source model and MCG measurements of a human and a frog. The magnetic field pattern is able to separate the meander line of 500/spl mu/m interval.