Compact readout electronics for 62-channel DROS magnetocardiogram system

Author

Kim, Jin-Mok ; Lee, Yong-Ho ; Kim, Kiwoong ; Kwon, Hyukchan ; Park, Yong-Ki ; Sasada, Ichiro

Author_Institution

Korea Res. Inst. of Stand. & Sci., Daejeon, South Korea

Volume

15

Issue

2

fYear

2005

fDate

6/1/2005 12:00:00 AM

Firstpage

644

Lastpage

647

Abstract

Compact and low-cost SQUID electronics to operate double relaxation oscillation SQUIDs (DROSs) has been constructed for detecting magnetocardiogram (MCG) fields. SQUID electronics consists of low-noise preamplifier with a white noise of 0.6 nV/√Hz, flux-locked loop (FLL) circuit with auto-reset, and interface circuit to control FLL using 3 digital lines from a computer. The automatic control software adjusts SQUID parameters to the optimum operating condition within 15 seconds for 62 channels. Outputs of FLL circuits are passed through the hardware filter box to the 64-channel data acquisition board. Each SQUID electronics for FLL and digital control is built together on a printed circuit board of 45 mm × 95 mm. When SQUID electronics is connected to DROS gradiometer with typical flux-to-voltage transfers of 1 mV/Φ_o, the noise contribution of FLL circuit is about 0.6 μΦ_o/√Hz or 0.6 fT/√Hz at 100 Hz, low enough to measure MCG fields.

Keywords

SQUID magnetometers; biomedical electronics; computerised instrumentation; magnetocardiography; readout electronics; 62-channel DROS magnetocardiogram system; DROS gradiometer; biomagnetism; biomedical electronics; compact readout electronics; computerised instrumentation; double relaxation oscillation SQUIDs; low-cost SQUID electronics; magnetocardiogram field detection; Automatic control; Circuits; Computer interfaces; Filters; Frequency locked loops; Hardware; Preamplifiers; Readout electronics; SQUIDs; White noise; Biomagnetism; DROS; FLL; MCG; SQUID; flux-locked loop; magnetocardiogram;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2005.849982

Filename

1439720