Integration Issues of Graphoepitaxial High- SQUIDs Into Multichannel MEG Systems

We have analyzed the possibility to construct multichannel magnetoencephalography (MEG) systems based on high-Tc direct current superconducting quantum interference devices (DC SQUIDs) with graphoepitaxial step edge Josephson junctions. A new layout of multilayer high-Tc superconducting flux transformers was tested and a new type of high-Tc DC SQUID magnetometer intended for MEG systems was realized. ameter 24 mm and a magnetic field resolution of ~4 fT/√Hz These magnetometers have a vacuum-tight capsule of outer diat 77 K. Crosstalk between adjacent sensors was estimated and measured for in-plane and axial configurations. The vibration-free cooling of sensors, minimization of the sensor-to-object distance and optimization of the sensor positions as well as the gantry design are discussed. Our findings may have implications for the next generation of noninvasive imaging techniques that will be used to understand human brain function.