DocumentCode :
835332
Title :
Tangential cardiomagnetic field measurement system based on double relaxation oscillation SQUID planar gradiometers
Author :
Lee, Yong-Ho ; Kim, Jin-Mok ; Kim, Kiwoong ; Kwon, Hyukchan ; Kim, In-Seon ; Park, Yong-Ki ; Ko, Young-Guk ; Chung, Namsik
Author_Institution :
Biomagnetism Res. Center, Korea Res. Inst. of Stand. & Sci., Daejeon, South Korea
Volume :
15
Issue :
2
fYear :
2005
fDate :
6/1/2005 12:00:00 AM
Firstpage :
648
Lastpage :
651
Abstract :
We present a 62-channel double relaxation oscillation SQUID (DROS) planar gradiometer system to measure magnetocardiogram (MCG) signals tangential to the chest surface. The DROSs were fabricated using Nb/Al-oxide/Nb junctions, and provided flux-to-voltage transfers of larger than 1 mV/Φ0 typically, which is large enough for direct readout by room-temperature flux-locked loop (FLL) circuits. The analog FLL circuits and digital control circuits are made in a single printed circuit board. The planar gradiometers are integrated, series-connected first-order pickup coils with a baseline of 4 cm. White noise level of the planar gradiometer is about 1.5 (fT/cm)/√Hz or 6 fT/√Hz, operated inside a magnetically shielded room. The planar gradiometers were arranged to measure dBx/dz and dBy/dz simultaneously. The covering area of the 62 channel system is 162 mm × 162 mm, which is smaller than the sensor coverage area of vertical measurement systems, but large enough to measure the essential MCG field distribution in a single position measurement.
Keywords :
SQUID magnetometers; aluminium compounds; biomedical electronics; magnetocardiography; niobium; readout electronics; relaxation oscillators; 62-channel double relaxation oscillation SQUID planar gradiometer system; DROS; Nb-Al-oxide-Nb junctions; Nb-AlO-Nb; direct readout; double relaxation oscillation SQUID planar gradiometers; flux-locked loop circuits; flux-to-voltage transfers; magnetocardiogram signals; tangential cardiomagnetic field measurement system; Area measurement; Cardiology; Coils; Digital control; Frequency locked loops; Magnetic field measurement; Niobium; Position measurement; Printed circuits; SQUIDs; Flux-locked loop; SQUID; magnetocardiogram; planar gradiometer;
fLanguage :
English
Journal_Title :
Applied Superconductivity, IEEE Transactions on
Publisher :
ieee
ISSN :
1051-8223
Type :
jour
DOI :
10.1109/TASC.2005.849983
Filename :
1439721
Link To Document :
بازگشت