Off-axis second-order high-TC rf SQUID gradiometer for magnetocardiography in unshielded environment

Hong-Chang Yang, Shu Yun Wang, Jen Tzong Jeng, Jau Han Chen, Herng-Er Horng

    研究成果: 雜誌貢獻Conference article同行評審

    12 引文 斯高帕斯(Scopus)


    We study an electronic gradiometer system for magnetocardiography (MCG) in unshielded environments. The electronically balanced gradiometer consists of three high temperature radio-frequency (rf) superconducting quantum interference device (SQUID) magnetometers, arranged in off-axis arrangement with the baseline of 6 cm to form the second order (2nd-order) gradiometer system. A set of coefficients were found to optimize the noise spectrum of the 2nd-order gradiometer via the fast Fourier transform technique by considering both the phase and the amplitude in the subtraction circuit. Besides, the signal of the 2nd-order gradiometer was filtered by notch and low frequency band pass filters. Hence, the field noise spectrum of the 2nd-order gradiometer was reduced to 1.5 pT/Hz1/2 at 60 Hz, to 1 pT/Hz1/2 at 10 Hz, and to 1.5 pT/Hz1/2 at 1 Hz. We perform MCG measurements in unshielded environments. To enhance the signal to noise ratio, the measured MCG signals were averaged according to the simultaneously recorded electrocardiogram signals recorded simultaneously. The MCG measurement was performed over several locations above the thorax of a human being. Our results demonstrate that the off-axis arrangement can offer the flexibility in the design of the SQUID-based multichannel magnetocardiogram.

    頁(從 - 到)360-363
    期刊IEEE Transactions on Applied Superconductivity
    發行號2 I
    出版狀態已發佈 - 2003 六月
    事件2002 Applied Superconductivity Conference - Houston, TX, 美国
    持續時間: 2002 八月 42002 八月 9

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Electrical and Electronic Engineering

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