We have obtained 1H NMR spectra simultaneously with high temporal resolution biomagnetic signals such as the magnetocardiogram (MCG) and magnetomyogram (MMG). The NMR spectra are acquired at measurement fields of 2-50 microT, with corresponding proton Larmor frequencies of 80-2000 Hz. Our measurements demonstrate a method suitable for MR imaging with concurrent measurement of biomagnetic signals that can provide sub-millisecond temporal resolution. The narrow line widths, reduction in susceptibility noise and enhanced spectral resolution at ultra low fields provide a new and extremely sensitive measurement method that may enable direct imaging of biological currents by detecting the phase or frequency shifts produced by magnetic fields arising from those currents. The results of our simultaneous measurements of NMR with MCG and MMG are compared to results from a current phantom to investigate the exciting potential of direct MRI of bioelectric currents.
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Biomed Opt Express
January 2025
State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China.
Optically-pumped magnetometer (OPM) has been of increasing interest for biomagnetic measurements due to its low cost and portability compared with superconducting quantum interference devices (SQUID). Miniaturized spin-exchange-relaxation-free (SERF) OPMs typically have limited bandwidth (less than a few hundred Hertz), making it difficult to measure high-frequency biomagnetic signals such as the magnetocardiography (MCG) signal of the mouse. Existing experiments mainly use SQUID systems to measure the signal.
View Article and Find Full Text PDFJ Neural Eng
January 2025
Biomagnetic Imaging Laboratory, University of California, San Francisco, 513 Parnassus Avenue, S362, San Francisco, CA 94143, United States of America.
electroencephalography (EEG) and magnetoencephalography (MEG) are widely used non-invasive techniques in clinical and cognitive neuroscience. However, low spatial resolution measurements, partial brain coverage by some sensor arrays, as well as noisy sensors could result in distorted sensor topographies resulting in inaccurate reconstructions of underlying brain dynamics. Solving these problems has been a challenging task.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China.
Energy loss in shielding soft magnetic materials at low frequencies (1-100 Hz) can cause fluctuations in the material's magnetic field, and the resulting magnetic noise can interfere with the measurement accuracy and basic precision physics of biomagnetic signals. This places higher demands on the credibility and accuracy of loss separation predictions. The current statistical loss theory (STL) method tends to ignore the high impact of the excitation dependence of quasi-static loss in the low-frequency band on the prediction accuracy.
View Article and Find Full Text PDFFront Med Technol
October 2024
Neuranics Limited, Glasgow, United Kingdom.
Motion artifacts can be a significant noise source in biomagnetic measurements when magnetic sensors are not separated from the signal source. In ambient environments, motion artifacts can be up to ten times stronger than the desired signals, varying with environmental conditions. This study evaluates the variability of these artifacts and the effectiveness of a gradiometer in reducing them in such settings.
View Article and Find Full Text PDFMicrosyst Nanoeng
August 2024
State Key Laboratory for Manufacturing Systems Engineering, International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies, Xi'an Jiaotong University (Yantai) Research Institute for Intelligent Sensing Technology and Systems, Xi'an Jiaotong University, Xi'an, 710049, China.
The chip-scale hybrid optical pumping spin-exchange relaxation-free (SERF) atomic magnetometer with a single-beam arrangement has prominent applications in biomagnetic measurements because of its outstanding features, including ultrahigh sensitivity, an enhanced signal-to-noise ratio, homogeneous spin polarization and a much simpler optical configuration than other devices. In this work, a miniaturized single-beam hybrid optical pumping SERF atomic magnetometer based on a microfabricated atomic vapor cell is demonstrated. Although the optically thin Cs atoms are spin-polarized, the dense Rb atoms determine the experimental results.
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