64-Channel Second-Order Planar Gradiometer System for Magnetocardiograms

A 64-channel planar gradiometer system was developed to measure magnetocardiogram (MCG) signals. The planar gradiometers are second-order planar gradiometers with a baseline of 50 mm, fabricated from Nb thin films on Si wafers using thin film processes. The SQUIDs were fabricated from Nb/Al-oxide/Nb...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2007-06, Vol.17 (2), p.831-834
Main Authors: Lee, Y.H., Kim, J.M., Yu, K.K., Kim, K., Kwon, H., Kim, I.S., Park, Y.K.
Format: Article
Language:English
Subjects:
Applied sciences
Area measurement
Circuit properties
Current measurement
Double relaxation oscillation SQUID
Electric, optical and optoelectronic circuits
Electronic circuits
Electronics
Exact sciences and technology
General equipment and techniques
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Magnetic devices
Magnetic field measurement
Magnetic measurements
Magnetic sensors
Magnetic shielding
magnetocardiogram
Magnetocardiograms
Niobium
Oscillators, resonators, synthetizers
Physics
planar gradiometer
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Semiconductor thin films
Sensors (chemical, optical, electrical, movement, gas, etc.)
remote sensing
Shields
SQUIDs
Superconducting devices
superconducting quantum interference device
Superconducting quantum interference devices
Superconductivity
Thin films
Thin wall structures
White noise
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Summary:A 64-channel planar gradiometer system was developed to measure magnetocardiogram (MCG) signals. The planar gradiometers are second-order planar gradiometers with a baseline of 50 mm, fabricated from Nb thin films on Si wafers using thin film processes. The SQUIDs were fabricated from Nb/Al-oxide/Nb junctions, and a double relaxation oscillation SQUID (DROS) scheme was used to have a large flux-to-voltage transfer, typically about 1 mV/Phi 0 . The planar gradiometers were arranged to measure magnetic field components tangential to the chest surface, which has a field distribution peak just above the current dipole. The diameter of the sensor coverage area is 190 mm, which was proved to be large enough to provide MCG field distribution in a single measurement. Inside a thin-wall shield room, the white noise level of the planar gradiometer system is about 8 fTradicHz. The 64-channel system was operated in a thin-wall shield room, and MCG signals were measured.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2007.898604