scholarly journals Low Field Optimization of a Non-Contacting High-Sensitivity GMR-Based DC/AC Current Sensor

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2564
Author(s):  
Cristian Mușuroi ◽  
Mihai Oproiu ◽  
Marius Volmer ◽  
Jenica Neamtu ◽  
Marioara Avram ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Giant Magnetoresistance ◽  
Detection System ◽  
High Sensitivity ◽  
Practical Method ◽  
Current Transformer ◽  
Current Sensor ◽  
Temperature Drift ◽  
Planar Coil ◽  
Gmr Sensor

Many applications require galvanic isolation between the circuit where the current is flowing and the measurement device. While for AC, the current transformer is the method of choice, in DC and, especially for low currents, other sensing methods must be used. This paper aims to provide a practical method of improving the sensitivity and linearity of a giant magnetoresistance (GMR)-based current sensor by adapting a set of design rules and methods easy to be implemented. Our approach utilizes a multi-trace current trace and a double differential GMR based detection system. This essentially constitutes a planar coil which would effectively increase the usable magnetic field detected by the GMR sensor. An analytical model is developed for calculating the magnetic field generated by the current in the GMR sensing area which showed a significant increase in sensitivity up to 13 times compared with a single biased sensor. The experimental setup can measure both DC and AC currents between 2–300 mA, with a sensitivity between 15.62 to 23.19 mV/mA, for biasing fields between 4 to 8 Oe with a detection limit of 100 μA in DC and 100 to 300 μA in AC from 10 Hz to 50 kHz. Because of the double differential setup, the detection system has a high immunity to external magnetic fields and a temperature drift of the offset of about −2.59 × 10−4 A/°C. Finally, this setup was adapted for detection of magnetic nanoparticles (MNPs) which can be used to label biomolecules in lab-on-a-chip applications and preliminary results are reported.

Verification and Design of High Precision Eddy Current Sensor for Tip Clearance Measurement

2018 ◽  
Author(s):  
Ziyu Zhao ◽  
Zhenxia Liu ◽  
Yaguo Lyu ◽  
Xinxin Xu
Keyword(s):  
High Precision ◽  
Eddy Current ◽  
High Sensitivity ◽  
Response Speed ◽  
Measurement Range ◽  
Tip Clearance ◽  
Current Sensor ◽  
Eddy Current Sensor ◽  
Planar Coil ◽  
Sensor Coil

A high precision eddy current sensor for tip clearance measurement was proposed to assess the dynamic tip clearance measurement for aero-engine rotator. Based on the Lenz’s law, the eddy current sensor has high sensitivity, quick response speed and strong anti-interference capability, in addition, the simple geometry and easy installation are its main merits. The aim is to study the influence of planar coil structure parameters and excitation signal parameters on the sensor coil measurement, provide the basis for design of practical sensor in turbine tip clearance measurement. The dynamic calibration experiment verified the designed planar sensor coil, the results indicated the sensor resolution was 10μm and the measurement range was not less than 3mm. The dynamic experiment proved the measuring range, resolution, response speed of designed sensor can meet the requirement of turbine blade tip clearance measurement. The work provides experience in eddy current sensor design in different application, not only in turbine. And the future work will focus on the high temperature issues.

Giant Magnetoresistance Imaging for NDE of Conductive Materials

1999 ◽  
Vol 591 ◽  
Author(s):  
E. S. Boltz ◽  
S. G. Albanna ◽  
A. R. Stallings ◽  
Y. H. Spooner ◽  
J. P. Abeyta
Keyword(s):  
Eddy Current ◽  
Giant Magnetoresistance ◽  
High Spatial Resolution ◽  
Low Frequency ◽  
High Sensitivity ◽  
Low Noise ◽  
Conductive Materials ◽  
Gmr Sensors ◽  
Current Sensors ◽  
Gmr Sensor

ABSTRACTTraditional coil-based eddy-current sensors are severely limited in their ability to detect small buried defects, defects under fasteners and deeply buried cracks and corrosion. TPL has developed eddy-current sensors and arrays based on the use of Giant Magnetoresistance (GMR) sensor elements. GMR offers high sensitivity, very wide bandwidth and low noise from DC to over 1 GHz. Coupled with the ability to fabricate GMR sensors with micron-level dimensions, these new eddy-current sensors offer an ideal technology for inspections requiring high spatial resolution and low-frequency, deeply-penetrating fields.

scholarly journals An Automated Sensing System for Steel Bridge Inspection Using GMR Sensor Array and Magnetic Wheels of Climbing Robot

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Rui Wang ◽  
Youhei Kawamura
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Giant Magnetoresistance ◽  
Sensor Array ◽  
Fatigue Cracks ◽  
Vertical Component ◽  
Steel Bridges ◽  
Steel Bridge ◽  
Sensing System ◽  
Gmr Sensor

Corrosion is one of the main causes of deterioration of steel bridges. It may cause metal loss and fatigue cracks in the steel components, which would lead to the collapse of steel bridges. This paper presents an automated sensing system to detect corrosion, crack, and other kinds of defects using a GMR (Giant Magnetoresistance) sensor array. Defects will change the relative permeability and electrical conductivity of the material. As a result, magnetic field density generated by ferromagnetic material and the magnetic wheels will be changed. The defects are able to be detected by using GMR sensor array to measure the changes of magnetic flux density. In this study, magnetic wheels are used not only as the adhesion device of the robot, but also as an excitation source to provide the exciting magnetic field for the sensing system. Furthermore, compared to the eddy current method and the MFL (magnetic flux leakage) method, this sensing system suppresses the noise from lift-off value fluctuation by measuring the vertical component of induced magnetic field that is perpendicular to the surface of the specimen in the corrosion inspection. Simulations and experimental results validated the feasibility of the system for the automated defect inspection.

scholarly journals High Sensitivity Differential Giant Magnetoresistance (GMR) Based Sensor for Non-Contacting DC/AC Current Measurement

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 323 ◽  
Author(s):  
Mușuroi ◽  
Oproiu ◽  
Volmer ◽  
Firastrau
Keyword(s):  
Measurement System ◽  
Giant Magnetoresistance ◽  
High Sensitivity ◽  
Measurement Range ◽  
Current Measurement ◽  
Local Fields ◽  
Temperature Drift ◽  
Wide Range ◽  
Extended Operation ◽  
High Flexibility

This paper presents the design and implementation of a high sensitivity giant magnetoresistance (GMR) based current sensor with a broad range of applications. The novelty of our approach consists in using a double differential measurement system, based on commercial GMR sensors, with an adjustable biasing system used to linearize the field response of the system. The work aims to act as a fully-operational proof of concept application, with an emphasis on the mode of operation and methods to improve the sensitivity and linearity of the measurement system. The implemented system has a broad current measurement range from as low as 75 mA in DC and 150 mA in AC up to 4 A by using a single setup. The sensor system is also very low power, consuming only 6.4 mW. Due to the way the sensors are polarized and positioned above the U-shaped conductive band through which the current to be measured is flowing, the differential setup offers a sensitivity of about between 0.0272 to 0.0307 V/A (signal from sensors with no amplifications), a high immunity to external magnetic fields, low hysteresis effects of 40 mA, and a temperature drift of the offset of about −2.59×10−4 A/°C. The system provides a high flexibility in designing applications where local fields with very low amplitudes must be detected. This setup can be redesigned for a wide range of applications, thus allowing further specific optimizations, which would provide an even greater accuracy and a significantly extended operation range.

Improvement of Gmr in NiFeCo/Cu Multilayers by a Layer - by - Layer Magnetic Field Sputtering

1995 ◽  
Vol 384 ◽  
Author(s):  
K. Saito ◽  
Y. Yanagida ◽  
Y. Obi ◽  
H. Itoho ◽  
H. Fujimori
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Domain Wall ◽  
Giant Magnetoresistance ◽  
High Sensitivity ◽  
Sputter Deposition ◽  
Spin Rotation ◽  
Layer By Layer ◽  
Wall Movement ◽  
Magnetic Layers

ABSTRACTNiFeCo/Cu multilayers fabricated by an improved magnetic field sputtering were investigated in order to achieve the soft GMR (giant magnetoresistance) with a high sensitivity at low magnetic fields. A magnetic field was applied to the film during sputter-deposition, and its field direction was changed alternately from layer to layer. Such an alternate field sputtering is called hereafter layer-by-layer magnetic field sputtering. The best GMR characteristics (large MR at low magnetic fields) were achieved when the angle between the directions of magnetic field applied to neighboring two magnetic layers was 90°. As one of the speculation, it has been considered that the result is attributed to the induced composite magnetic anisotropy which causes the magnetization to occur more dominantly by spin rotation than by domain wall movement.

LOW-FIELD INHOMOGENEITY-INDUCED MAGNETORESISTANCE IN SILICON

SPIN ◽  
2012 ◽  
Vol 02 (01) ◽  
pp. 1250002 ◽  
Author(s):  
XIAOZHONG ZHANG ◽  
CAIHUA WAN
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Giant Magnetoresistance ◽  
High Sensitivity ◽  
Boundary Region ◽  
Charge Carriers ◽  
Silicon Devices ◽  
Low Field ◽  
Silicon Based ◽  
The Magnetic Field

We show that inhomogeneity-induced magnetoresistance (IMR) in lightly doped silicon can be significantly enhanced through the injection of minority charge carriers, and then tuned by an applied current to have an onset at low magnetic fields. We designed an IMR device in which, the inhomogeneity is provided by the p–n boundary formed between regions where conduction is dominated by the minority and majority charge carriers respectively; application of a magnetic field distorts the current in the boundary region, resulting in large magnetoresistance. The room-temperature field sensitivity of our IMR device at low fields was remarkably improved, with magnetoresistance reaching 10% at 0.07 T and 100% at 0.2 T, approaching the performance of commercial giant magnetoresistance devices. The combination of high sensitivity to low magnetic fields and large high-field response should make this device concept attractive to the magnetic field sensing industry. Moreover, being based on a conventional silicon platform, it should be possible to integrate with existing silicon devices and so aid the development of silicon-based magnetoelectronics.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

High-sensitivity fiber optic magnetic field sensor based on lossy mode resonance and hollow core-offset structure

2021 ◽  
pp. 1-12
Author(s):  
Xue-Peng Jin ◽  
Hong-Zhi Sun ◽  
Shuo-Wei Jin ◽  
Wan-Ming Zhao ◽  
Jing-Ren Tang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fiber Optic ◽  
High Sensitivity ◽  
Magnetic Field Sensor ◽  
Hollow Core ◽  
Field Sensor

scholarly journals A tandem giant magnetoresistance assay for one-shot quantification of clinically relevant concentrations of N-terminal pro-B-type natriuretic peptide in human blood

2021 ◽  
Author(s):  
Fanda Meng ◽  
Weisong Huo ◽  
Jie Lian ◽  
Lei Zhang ◽  
Xizeng Shi ◽  
...  
Keyword(s):  
Detection Limit ◽  
Giant Magnetoresistance ◽  
Dynamic Range ◽  
Point Of Care ◽  
Sample Volume ◽  
Small Sample ◽  
Broad Dynamic Range ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Sample Volume Requirement

AbstractWe report a microfluidic sandwich immunoassay constructed around a dual-giant magnetoresistance (GMR) sensor array to quantify the heart failure biomarker NT-proBNP in human plasma at the clinically relevant concentration levels between 15 pg/mL and 40 ng/mL. The broad dynamic range was achieved by differential coating of two identical GMR sensors operated in tandem, and combining two standard curves. The detection limit was determined as 5 pg/mL. The assay, involving 53 plasma samples from patients with different cardiovascular diseases, was validated against the Roche Cobas e411 analyzer. The salient features of this system are its wide concentration range, low detection limit, small sample volume requirement (50 μL), and the need for a short measurement time of 15 min, making it a prospective candidate for practical use in point of care analysis.

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