Title :
Neuromagnetic SQUID measurements in a helmet-type superconducting magnetic shield of BSCCO
Author :
Ohta, H. ; Koike, A. ; Hoshino, K. ; Kotaka, H. ; Sudoh, E. ; Kato, K. ; Takahara, H. ; Uchikawa, Y. ; Shinada, K. ; Takahata, M. ; Yamada, Y. ; Matsui, T.
Author_Institution :
Inst. of Phys. & Chem. Res., Saitama, Japan
fDate :
3/1/1993 12:00:00 AM
Abstract :
A superconducting quantum interference device (SQUID) magnetometer has successfully detected magnetic fields emitted from a human brain in a helmet-size superconducting magnetic shield of the high-T/sub c/ superconductor Bi-Sr-Ca-Cu-O/sub x /(BSCCO). The sensitivities of the RF-SQUID and the DC-SQUID of quasi-planar Josephson junctions-superconducting weak links are 20 fT/ square root Hz and 4 fT/ square root Hz, respectively. The magnetic shield can reduce a magnetic field to -120 dB or 10/sup -6/ even at as low a frequency as 0.2 Hz. The authors have detected somatosensory evoked magnetic fields stimulating the tibial nerves of the patient by current pulses.<>
Keywords :
SQUIDs; biomagnetism; biomedical measurement; bismuth compounds; brain; calcium compounds; high-temperature superconductors; magnetic field measurement; magnetic shielding; magnetometers; neurophysiology; somatosensory phenomena; strontium compounds; Bi-Sr-Ca-Cu-O; DC-SQUID; RF-SQUID; current pulses; helmet-type superconducting magnetic shield; high-T/sub c/ superconductor; human brain; magnetic fields; magnetometer; neuromagnetic SQUID measurements; quasi-planar Josephson junctions-superconducting weak links; sensitivities; somatosensory evoked magnetic fields; superconducting quantum interference device; tibial nerves; Bismuth compounds; Humans; Interference; Josephson junctions; Magnetic devices; Magnetic field measurement; Magnetic shielding; SQUID magnetometers; Superconducting devices; Superconducting magnets;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
