Title :
A modular low noise 7-channel SQUID-magnetometer
Author :
Dössel, O. ; David, B. ; Fuchs, M. ; Kullmann, W.H. ; Lüdeke, K.M.
Author_Institution :
Philips GmbH, Hamburg, Germany
fDate :
3/1/1991 12:00:00 AM
Abstract :
A modular low-noise seven-channel SQUID-magnetometer for biomagnetic measurements was developed. The DC-SQUIDs are prepared by thin film technology based on the materials NbN-MgO-NbN, and show a flux noise below 10 μΦ0/√Hz. The signal is picked up with first-order wire-wound gradiometers of 2-cm diameter and coupled to the SQUIDs by integrated coupling coils. Individual channels can be replaced from the system, and various gradiometers can be used giving a flexible modular system. The electronics are based on the flux-locked-loop method extended by a bias modulation technique to reduce 1/f noise. The overall system noise is below 20 fT/√Hz. Biomagnetic measurements on auditory evoked fields have been carried out
Keywords :
SQUIDs; biomagnetism; magnetometers; patient diagnosis; 1/f noise reduction; 2 cm; DC-SQUIDs; NbN-MgO-NbN; auditory evoked fields; bias modulation technique; biomagnetic measurement; biomagnetic measurements; flexible modular system; flux noise; flux-locked-loop method; integrated coupling coils; low noise SQUID magnetometer; modular SQUID magnetometer; seven-channel SQUID-magnetometer; system noise; thin film technology; wire-wound gradiometers; Biomagnetics; Coils; Electrodes; Inductance; Magnetic field measurement; Niobium; Plasma applications; SQUIDs; Sputter etching; Sputtering;
Journal_Title :
Magnetics, IEEE Transactions on
