Double relaxation oscillation SQUID with reference junction for biomagnetic multichannel applications

Lee, Y.H.; Kwon, Hyuk‐Chan; Kim, J.M.; Park, Y.K.; Park, J.C.

doi:10.1016/s0964-1807(98)00063-5

Cited by 27 publications

(18 citation statements)

References 12 publications

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“…The MCG system utilizes double relaxation oscillation Superconducting Quantum Interference Device sensors [69][70]. The average noise spectral density of the whole system in a magnetic shielded room is 10 fT/√Hz @ 1 Hz and 5 fT/√Hz @ 100 Hz.…”

Section: Mcg Recording and Data Processingmentioning

confidence: 99%

Current Status and Future of Cardiac Mapping in Atrial Fibrillation

Kim¹,

Ahn²

2012

Atrial Fibrillation - Basic Research and Clinical Applications

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Section: Mcg Recording and Data Processingmentioning

confidence: 99%

Current Status and Future of Cardiac Mapping in Atrial Fibrillation

Kim¹,

Ahn²

2012

Atrial Fibrillation - Basic Research and Clinical Applications

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“…The MCG system uses double relaxation oscillation SQUID (DROS) sensors. 9,10 The average noise spectral density of the entire system in a magnetically shielded room is 10 fT/ Hz at 1 Hz and 5 fT/ Hz over 100 Hz. The KRISS 64-channel MCG has 64 planar first-order SQUID gradiometers, which measurd the tangential components of the cardiomagnetic fields.…”

Section: Mcg Recording and Interpretationmentioning

confidence: 99%

Magnetic Dispersion of the Late Repolarization in Brugada Syndrome

Joung

Kim

Lee

et al. 2008

Circ J

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Background Magnetocardiography (MCG) is a new noninvasive modality for recording cardiac depolarization and repolarization and was used in the present study to evaluate abnormalities in patients with Brugada syndrome (BS). Methods and ResultsThe MCG findings of 10 BS, 21 right bundle branch block (RBBB), and 34 normal patients were compared. On the horizontal spatiotemporal activation graph (STAG), the r' waves were more frequently located on the right side in the RBBB than in the normal (p=0.001) or BS groups (p=0.001). The maximum current angles of the r' wave fell into the northwest axis in all BS patients as compared to having a right axis deviation in 19 of 21 RBBB patients (90.4%, p=0.001). In the magnetic field and current density vector maps during late repolarization, the BS group had a non-dipole pattern more frequently and a higher number of poles compared with the normal (p=0.001) and RBBB groups (p=0.001). Conclusions During depolarization, the horizontal STAG location and maximum current angle of the r' wave were beneficial in differentiating BS from RBBB and normal. The magnetic dispersion was a more frequently observed finding in BS patients than in RBBB and normal patients during late repolarization. (Circ J 2008; 72: 94 -101)

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“…Peaks between 1 Hz and 100 Hz are caused by external environmental noises. When the output passes through the filter system, the noise level is 600 equivalent to 6 in the white region. 60 Hz noise and other environmental noises disappear, and output signals over 100 Hz are cut off.…”

Section: A the Single Channel Dros Systemmentioning

confidence: 99%

“…DROS provides large flux-to-voltage transfer coefficients, typically about 10 times larger than dc SQUID [6], and simple flux-locked loop (FLL) circuit [7]. However, consisting of a hysteretic dc SQUID (the signal SQUID) and a hysteretic junction (the reference junction), shunted by a relaxation circuit of an inductor and a resistor, DROS generally generates a relaxation frequency of the order of 1 GHz.…”

Section: Introductionmentioning

confidence: 99%

Compact Readout Electronics for 62-Channel DROS Magnetocardiogram System

Kim

Lee

Kim

et al. 2005

IEEE Trans. Appl. Supercond.

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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 8 o , the noise contribution of FLL circuit is about 0.6 8 o Hz or 0.6 fT Hz at 100 Hz, low enough to measure MCG fields.

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Double relaxation oscillation SQUID with reference junction for biomagnetic multichannel applications

Cited by 27 publications

References 12 publications

Current Status and Future of Cardiac Mapping in Atrial Fibrillation

Current Status and Future of Cardiac Mapping in Atrial Fibrillation

Magnetic Dispersion of the Late Repolarization in Brugada Syndrome

Compact Readout Electronics for 62-Channel DROS Magnetocardiogram System

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