Magnetoencephalography using high temperature rf SQUIDs.
We have developed high-critical-temperature radio-frequency Super conducting QUantum Interference Devices (SQUIDs) with step-edge grain-boundary Josephson junctions and large flux focusers. These planar devices were fabricated from epitaxial YBa2Cu3O7 films and operated in the magnetometer and first-order gradiometer configurations while immersed in liquid nitrogen. At the temperature of 77K, we have attained a magnetic field resolution for the magnetometer better than 200 fT/Hz1/2 down to less than 1 Hz, i.e., over the low signal frequency range important for medical diagnostics. The results to date show a high promise for biomagnetic diagnostics. For the first time, we recorded the evoked responses from human brains using a high-temperature magnetometer and a first-order electronic gradiometer channel simultaneously. These results were obtained in a magnetically shielded room. An improvement in the magnetic field resolution by another order of magnitude is possible and probable.
Zhang
Y
Y
Forschungszentrum Jülich, Institut für Schicht- und Ionentechnik (ISI), Germany.
Tavrin
Y
Y
Mück
M
M
Braginski
A I
AI
Heiden
C
C
Hampson
S
S
Pantev
C
C
Elbert
T
T
D000161:Acoustic Stimulation; D001921:Brain / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation*; D008297:Male