Abstract

In order to further improving noise performance and achieving higher spatial resolution for bio-magnetic sensing, there is a tendency to develop a multi-channel integrated system for micro magnetic sensors. In this study, we have developed a high resolution programmable oversampling MI sensor system, as a unit module for multi-channel integrated bio-sensor system, based on Pk-pk VD-type MI magnetometer. We have achieved a high field detection sensitivity with good linearity, and a noise level lower than 1 pT/Hz1/2, by utilizing the time-differential measurement in each MI element for suppressing the low frequency noise components and increasing the stability of sensor system. Meanwhile, the proposed MI sensor system can be easily enlarged into multi-channel system, and is more suitable for integration and mass production. Furthermore, we have successfully achieved the real time R peak and T wave measurements of magnetocardiography (MCG) via new MI sensor system, with a high real time signal-to-noise ratio (SNR) of about 20 dB. We have at the first time achieved the clear P wave measurements of MCG using MI sensor, in an unshielded environment. The real time MCG measurements via new MI sensor system at room temperature, in an unshielded environment, will contribute to the diagnosis of heart disease.

Highlights

  • As a high-performance magnetic sensor, magneto-impedance (MI) sensor has attracted considerable attention and has wide prospects in geomagnetic detection and bio-sensing.1 Comparing with other magnetic sensors, MI sensor has very high sensitivity, and pico-tesla resolution which is coming up with Superconducting Quantum Interference Devices

  • Comparing with previous system, proposed MI sensor system is programed by Python and controlled by field-programmable gate array (FPGA) which are low development cost and convenient to be developed for various experiments and application

  • Comparing with conventional MI sensor gradiometer, this proposed system achieves a higher sensitivity, and an extremely low noise level about 700 fT, with a high compatibility for extremely weak magnetic field measurements. It can be enlarged into multi-channel system, and is more suitable for integration and mass production

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Summary

INTRODUCTION

As a high-performance magnetic sensor, magneto-impedance (MI) sensor has attracted considerable attention and has wide prospects in geomagnetic detection and bio-sensing. Comparing with other magnetic sensors, MI sensor has very high sensitivity, and pico-tesla resolution which is coming up with Superconducting Quantum Interference Devices. As a high-performance magnetic sensor, magneto-impedance (MI) sensor has attracted considerable attention and has wide prospects in geomagnetic detection and bio-sensing.. MI sensor has been used for measuring bio-magnetic fields in living cell tissue preparations and Magneto-encephalogram (MEG).. In order to detecting MCG and MEG signals for diagnosis of heart and brain diseases, via MI sensor, it’s necessary to further improve noise performance into fT level. For achieving MCG and MEG mappings, there is a tendency to develop a multi-channel integrated MI sensor system with high spatial resolution, which is a main advantageous of MI sensor. We have developed a high resolution programmable oversampling MI sensor system, as a unit module for multi-channel integrated bio-sensor system, based on Pk-pk VD-type MI magnetometer.

PROGRAMMABLE OVERSAMPLING MI SENSOR SYSTEM
Field detection characteristics
Noise analysis
MAGNETOCARDIOGRAPHY MEASUREMENTS
Findings
CONCLUSION
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