Title :
A YBa/sub 2/Cu/sub 3/O/sub 7/ thin film SQUID gradiometer for measurements in unshielded space
Author :
Tavrin, Y. ; Zhang, Y. ; Muck, M. ; Braginski, A.I. ; Heiden, C.
Author_Institution :
Inst. fur Schicht und Ionentechnik, Forschungszentrum Julich, Germany
fDate :
3/1/1993 12:00:00 AM
Abstract :
Low-noise RF superconducting quantum interference device (SQUID) washers fabricated from YBa/sub 2/Cu/sub 3/O/sub 7/ epitaxial thin films have been used to construct a first-order electronic gradiometer operating at 77 K and suitable for biomagnetic measurements. Mechanical adjustment of one SQUID´s plane in a gradiometric setup, which consisted of two SQUIDs separated by a vertical 6-cm base, made it possible to attenuate signals due to far DC magnetic field sources by three orders of magnitude. A magnetic field resolution of 280 fT/ square root Hz above 2 Hz was attained through the use of large thin-film and bulk flux focusers. The fine structure of human-heart magnetocardiograms could be recorded in unshielded space. In a shielded room, magnetoencephalograms were obtained. The system was used to obtain new data on the acoustically evoked cortical response.<>
Keywords :
SQUIDs; barium compounds; biomagnetism; biomedical electronics; biomedical equipment; biomedical measurement; high-temperature superconductors; magnetometers; superconducting thin films; thin film devices; yttrium compounds; 77 K; SQUID gradiometer; YBa/sub 2/Cu/sub 3/O/sub 7/ thin film; acoustically evoked cortical response; biomagnetic measurements; bulk flux focusers; epitaxial thin films; first-order electronic gradiometer; human-heart magnetocardiograms; low noise RF type; magnetoencephalograms; superconducting quantum interference device; unshielded space; Magnetic field measurement; Magnetic flux; Magnetic separation; Magnetic shielding; Radio frequency; Radiofrequency interference; SQUIDs; Superconducting devices; Superconducting epitaxial layers; Superconducting magnets;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
