Title :
Operation of a hybrid 28-channel neuromagnetometer
Author :
Foglietti, V. ; Pasquarelli, A. ; Pizzella, V. ; Torrioli, G. ; Romani, G.L. ; Casciardi, S. ; Gallagher, W.J. ; Ketchen, M.B. ; Kleinsasser, A.W. ; Sandstrom, R.L.
Author_Institution :
IESS-CNR, Rome, Italy
fDate :
3/1/1993 12:00:00 AM
Abstract :
A 28-channel system for neuromagnetic measurements operative at CNR-IESS (Instituto di Elettronica dello Stato Solido) is described. The instrument uses 28 Nb/PbAuIn DC-SQUID (superconducting quantum interference device) sensors coupled with a flux transformer configuration. The detection coils are arranged on concentric circumferences. Sixteen axial first-order gradiometers are arranged in the internal circles, while the external circle consists of 12 first-order planar gradiometers. The vertical gradiometers show a white noise level of approximately=5 fT/ square root Hz, while the planar ones have a noise approximately=6 fT/cm square root Hz, with a 1/f corner at a few hertz. The evoked potentials of normal subjects and patients affected by various kinds of vascular disturbances have been studied. The system has succeeded at one-shot localization of some cortical activity. The instrument has also been used to record the spontaneous brain activity in patients affected by focal epilepsy.<>
Keywords :
SQUIDs; bioelectric potentials; biomagnetism; biomedical equipment; biomedical measurement; brain; magnetometers; medical signal processing; white noise; DC SQUID sensors; MEG; Nb-PbAuIn; axial first-order gradiometers; cortical activity; evoked potentials; first-order planar gradiometers; flux transformer configuration; focal epilepsy; hybrid 28-channel neuromagnetometer; one-shot localization; spontaneous brain activity; vascular disturbances; white noise level; Brain; Instruments; Interference; Niobium; Noise level; SQUIDs; Superconducting coils; Superconducting device noise; Superconducting devices; White noise;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
