Title :
An integrated DC SQUID gradiometer for biomagnetic application
Author :
Koyanagi, M. ; Kasai, N. ; Chinone, K. ; Nakanishi, M. ; Kosaka, S. ; Higuchi, M. ; Kado, H.
Author_Institution :
Electrotech. Lab., Ibaraki, Japan
fDate :
3/1/1989 12:00:00 AM
Abstract :
A first-order off-diagonal gradiometer was fabricated and tested. The gradiometer consisted of two field pickup coils and a planar DC SQUID (superconducting quantum interference device) with two superconducting loops connected in parallel, two multiturn input coils, and a modulation-feedback coil. The size of the pickup coils was 6×6 mm2 with a base line of 8 mm. The overall size of the gradiometer was 15×7.5 mm2. The resolution of the magnetic field gradient of the gradiometer increased from 11 to 1.8 pT/m√Hz (the noise limits), corresponding to the frequencies from 1 Hz to 600 Hz. The resolution became nearly white in a frequency range above 600 Hz. The intrinsic balance of the gradiometer was better than 1000 p.p.m. for the field perpendicular to its plane
Keywords :
SQUIDs; biological techniques and instruments; biomagnetism; magnetometers; biomagnetic application; field pickup coils; first-order off-diagonal gradiometer; integrated DC SQUID gradiometer; intrinsic balance; modulation-feedback coil; multiturn input coils; noise limits; superconducting loops; Biomagnetics; Frequency; Interference; Magnetic fields; Magnetic noise; SQUIDs; Superconducting coils; Superconducting device noise; Superconducting devices; Testing;
Journal_Title :
Magnetics, IEEE Transactions on
