A thin film magnetic field sensor of sub-pT resolution and magnetocardiogram (MCG) measurement at room temperature

S. Yabukami, K. Kato, Y. Ohtomo, T. Ozawa, K. I. Arai

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

We developed a very sensitive high-frequency carrier-type thin film sensor with a sub-pT resolution using a transmission line. The sensor element consists of Cu conductor with a meander pattern (20 mm in length, 0.8 mm in width, and 18 μm in thickness), a ground plane, and amorphous CoNbZr film (4 μm in thickness). The amplitude modulation technique was employed to enhance the magnetic field resolution for measurement of the high-frequency field (499 kHz), a resolution of 7.10×10-13 T/Hz1/2 being achieved, when we applied an AC magnetic field at 499 kHz. The phase detection technique was applied for measurement of the low frequency field (around 1 Hz). A small phase change was detected using a dual mixer time difference method. A high phase change of 130°/Oe was observed. A magnetic field resolution of 1.35×10-12 T/Hz1/2 was obtained when a small AC field at 1 Hz was applied. We applied the sensor for magnetocardiogram (MCG) measurement using the phase detection technique. We succeeded in measuring the MCG signal including typical QRS and T waves, and compared the MCG with a simultaneously obtained conventional electrocardiogram (ECG) signal.

Original languageEnglish
Pages (from-to)675-678
Number of pages4
JournalJournal of Magnetism and Magnetic Materials
Volume321
Issue number7
DOIs
Publication statusPublished - 2009 Apr

Keywords

  • Magnetic field sensor
  • Magnetocardiogram
  • Thin film sensor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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