Low-noise biomagnetic measurements with a multichannel dc-SQUID system at 77 K

Author

Barthelmess, H.-J. ; Halverscheid, M. ; Schiefenhövel, B. ; Heim, E. ; Schilling, M. ; Zimmermann, R.

Author_Institution

Inst. fur Angewandte Phys., Hamburg Univ., Germany

Volume

11

Issue

1

fYear

2001

fDate

3/1/2001 12:00:00 AM

Firstpage

657

Lastpage

660

Abstract

Directly coupled dc-SQUID magnetometers made from the high-temperature superconductor (HTS) YBa₂Cu₃O₇ on symmetric 24° and 30° SrTiO₃-bicrystals have been optimized for low-noise operation in static magnetic fields. These magnetometers are encapsulated, for reliable operation in liquid nitrogen. In our small glass cryostat, allowing even mobile applications, up to 24 magnetometers can be mounted in three levels for gradiometer arrangements. With first-order gradiometers an external noise suppression of more than a factor of 100 is achieved. In a magnetically shielded chamber we find a typical noise √S_B (77 K, 10 Hz) of less than 50 fT/√Hz and low-noise magnetocardiograms are recorded. Due to the low noise of the dc-SQUID sensors also electrically stimulated magnetoencephalography measurements were possible

Keywords

SQUID magnetometers; barium compounds; biosensors; high-temperature superconductors; magnetocardiography; magnetoencephalography; superconducting device noise; yttrium compounds; 77 K; SrTiO₃; SrTiO₃ bicrystal substrate; YBa₂Cu₃O₇; biomagnetic measurement; encapsulation; gradiometer; high temperature superconductor; low-noise operation; magnetically shielded chamber; magnetocardiography; magnetoencephalography; multichannel DC-SQUID; static magnetic field sensor; Biomagnetics; Couplings; High temperature superconductors; Magnetic fields; Magnetic noise; Magnetic shielding; Magnetometers; Nitrogen; Superconducting device noise; Superconducting magnets;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.919430

Filename

919430