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

Volume

27

Issue

2

fYear

1991

fDate

3/1/1991 12:00:00 AM

Firstpage

2797

Lastpage

2800

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;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.133790

Filename

133790