Magnetocardiography and magnetoencephalography measurements at room temperature using tunnel magneto-resistance sensors

Fujiwara, Kosuke; Oogane, Mikihiko; Kanno, Akira; Imada, Masahiro; Jono, Junichi; Terauchi, Takashi; Okuno, Tetsuo; Aritomi, Yuuji; Morikawa, Masahiro; Tsuchida, Masanori; Nakasato, Nobukazu; Ando, Yasuo

doi:10.7567/apex.11.023001

Cited by 103 publications

(62 citation statements)

References 32 publications

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“…Among magnetoresistive sensors, TMR-based sensors are good candidates for measuring fields from the heart and, possibly, the brain. TMR magnetometers for measurement of these signals (Fujiwara et al [18]) achieve a limit of detection of 14 pT/√Hz. Significant work dedicated to the development of a roadmap for MR magnetometers (and the current status of such sensors in more detail) was recently published by Zheng et al [25].…”

Section: Point Of Care Diagnosticsmentioning

confidence: 99%

mentioning

confidence: 99%

“…A list of the common and modern magnetic field sensors with the potential to be used for the detection of biomagnetic signals (magnetocardiography (MCG), magnetoencephalography (MEG), magnetomyography (MMG), magnetoneurography (MNG)) and for point-of-care devices[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

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confidence: 99%

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Ultrasensitive Magnetic Field Sensors for Biomedical Applications

Murzin

Mapps

Levada

et al. 2020

Sensors

173

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The development of magnetic field sensors for biomedical applications primarily focuses on equivalent magnetic noise reduction or overall design improvement in order to make them smaller and cheaper while keeping the required values of a limit of detection. One of the cutting-edge topics today is the use of magnetic field sensors for applications such as magnetocardiography, magnetotomography, magnetomyography, magnetoneurography, or their application in point-of-care devices. This introductory review focuses on modern magnetic field sensors suitable for biomedicine applications from a physical point of view and provides an overview of recent studies in this field. Types of magnetic field sensors include direct current superconducting quantum interference devices, search coil, fluxgate, magnetoelectric, giant magneto-impedance, anisotropic/giant/tunneling magnetoresistance, optically pumped, cavity optomechanical, Hall effect, magnetoelastic, spin wave interferometry, and those based on the behavior of nitrogen-vacancy centers in the atomic lattice of diamond.

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Section: Point Of Care Diagnosticsmentioning

confidence: 99%

mentioning

confidence: 99%

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Ultrasensitive Magnetic Field Sensors for Biomedical Applications

Murzin

Mapps

Levada

et al. 2020

Sensors

173

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“…Since the permeability of the biological tissues is like the permeability of free space, the magnetic field recordings from the brain have high spatial as well as temporal resolution. In this respect, linear MR sensors [138][139][140][141][142] have been investigated for neural signal recording.…”

Section: Mr Biosensors For Brain Mappingmentioning

confidence: 99%

Advances in Magnetoresistive Biosensors

Saha

et al. 2019

Micromachines

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Magnetoresistance (MR) based biosensors are considered promising candidates for the detection of magnetic nanoparticles (MNPs) as biomarkers and the biomagnetic fields. MR biosensors have been widely used in the detection of proteins, DNAs, as well as the mapping of cardiovascular and brain signals. In this review, we firstly introduce three different MR devices from the fundamental perspectives, followed by the fabrication and surface modification of the MR sensors. The sensitivity of the MR sensors can be improved by optimizing the sensing geometry, engineering the magnetic bioassays on the sensor surface, and integrating the sensors with magnetic flux concentrators and microfluidic channels. Different kinds of MR-based bioassays are also introduced. Subsequently, the research on MR biosensors for the detection of protein biomarkers and genotyping is reviewed. As a more recent application, brain mapping based on MR sensors is summarized in a separate section with the discussion of both the potential benefits and challenges in this new field. Finally, the integration of MR biosensors with flexible substrates is reviewed, with the emphasis on the fabrication techniques to obtain highly shapeable devices while maintaining comparable performance to their rigid counterparts.

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“…In recent years, several high-sensitivity magnetic sensors that can operate at room temperature have been developed. Among these sensors, a uxgate magnetometer [2,3], a tunnel magneto-resistance (TMR) sensor [4], and a magneto-impedance (MI) sensor [5] can measure a magnetocardiogram. Reference 2, 3 and 4 described the development of 32-channel, 36-channel and single-channel MCG measurement systems, respectively, and demonstrated MCG measurement using an MSR.…”

Section: Introductionmentioning

confidence: 99%

Study of Spatial Filter for Magnetocardiography Measurements without a Magnetically Shielded Room

Ogata

Tanaka

Hata

et al. 2019

ABE

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Magnetocardiography (MCG) is an effective modality for clinical application and health monitoring due to non-contact measurement and mapping of heart activity at high spatial resolution. A superconducting quantum interference device (SQUID) magnetometer is usually used for measuring MCG signals. However, a SQUID magnetometer has high running cost due to the liquid helium. Moreover, measuring MCG signals inside a magnetically shielded room (MSR) can be costly. Therefore, we developed a 64-channel magneto-impedance (MI) sensor system that does not require an MSR. However, the MCG measurement has very high noise level without an MSR. In this paper, we discuss the signal processing techniques of various noise reduction methods to decrease very loud noises. In particular, we investigated three spatial lter conditions that decrease correlated noises among the 64-channel signals to achieve a high peak value of MCG signals. By using a spatial lter that uses the average of the circumference channels and gradient, the distortion of MCG signals can be reduced. The average reduction in amplitude of the R wave as a result of using a spatial lter was 4.5 pT. Furthermore, the signal to noise ratio (SNR) of the P wave was 29.1 dB, while that of the R wave was 42.3 dB, and clear MCG signals were obtained when using the spatial lter that uses the average of the circumference channels and the gradient. Finally, we successfully measured the MCG signals without an MSR.

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Magnetocardiography and magnetoencephalography measurements at room temperature using tunnel magneto-resistance sensors

Cited by 103 publications

References 32 publications

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

Advances in Magnetoresistive Biosensors

Study of Spatial Filter for Magnetocardiography Measurements without a Magnetically Shielded Room

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