scholarly journals PT-Level High-Sensitivity Magnetic Sensor with Amorphous Wire

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 161 ◽  
Author(s):  
Dongfeng He
Keyword(s):  
Magnetic Field ◽  
Direct Current ◽  
High Sensitivity ◽  
Signal Amplitude ◽  
Magnetic Sensor ◽  
Resonant Circuit ◽  
Testing System ◽  
Amorphous Wire ◽  
Current Testing ◽  
The Magnetic Field

A picotesla (PT) level high-sensitivity magnetic sensor with amorphous wire was developed. The magnetic sensor was composed of a (Fe0.06Co0.94)72.5Si2.5B15 (FeCoSiB) amorphous wire with a coil wound around it. The amorphous wire had a diameter of 0.1 mm and a length of 5 mm. The coil was 30 turns. There was no electrical connection with the amorphous wire. The sensor was biased by an alternating current (AC) of about 1 MHz and a direct current (DC). To increase the sensitivity, a resonant circuit was used, and the signal amplitude of the magnetic sensor was increased 10 times from 10 mV/Gauss to about 100 mV/Gauss. The magnetic field resolution was improved 5 times from 30 pT/√Hz to 6 pT/√Hz. An eddy current testing system with a magnetic sensor was developed, and the artificial defects in an aluminum plate were evaluated.

scholarly journals A Feedback Method to Improve the Dynamic Range and the Linearity of Magnetoimpedance Magnetic Sensor

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Dongfeng He
Keyword(s):  
Magnetic Field ◽  
Steel Plate ◽  
Dynamic Range ◽  
Magnetic Sensor ◽  
Magnetic Field Sensor ◽  
Amorphous Wire ◽  
Alloy Plate ◽  
Field Sensor ◽  
Feedback Method ◽  
The Magnetic Field

We developed a high-sensitivity magnetoimpedance magnetic field sensor using a FeCoSiB amorphous wire and a coil wound around it. The amorphous wire had the diameter of 0.1 mm and the length of 5 mm. The magnetic field resolution of about 20 pT/√Hz was achieved. But the dynamic range of the magnetoimpedance magnetic field sensor was only about ±0.7 Gauss, which was not enough for some applications, such as the defect evaluation of steel plate. The linearity of the system was also not good when big magnetic field was applied, which will cause some noise when the system is used in unshielded environment. We developed a feedback method to improve the dynamic range and the linearity of the magnetic field sensor. The operation point of the magnetic field sensor was fixed by sending a feedback current to the coil. Using the feedback method, the dynamic range was improved from ±0.7 Gauss to ±10 Gauss and the linearity was also improved over 100 times better. An eddy current testing system using the magnetic sensor was developed, and the crack defects in steel plate and in 3D-printed titanium alloy plate were evaluated.

Evaluation of 3D-Printed titanium alloy using eddy current testing with high-sensitivity magnetic sensor

2019 ◽  
Vol 102 ◽  
pp. 90-95 ◽  
Author(s):  
Dongfeng He ◽  
Zhi Wang ◽  
Masahiro Kusano ◽  
Satoshi Kishimoto ◽  
Makoto Watanabe
Keyword(s):  
Titanium Alloy ◽  
Eddy Current ◽  
High Sensitivity ◽  
Eddy Current Testing ◽  
Magnetic Sensor ◽  
Current Testing ◽  
3D Printed

Low Frequency Measurements in Amorphous Wire for Studying GMI Effect

2011 ◽  
Vol 495 ◽  
pp. 201-204
Author(s):  
Polykseni Vourna
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Major Change ◽  
Wheatstone Bridge ◽  
Amorphous Wire ◽  
Dc Voltage ◽  
Gmi Effect ◽  
Offset Voltage ◽  
Ac Current ◽  
The Magnetic Field

When a soft ferromagnetic material is flown by an ac current and a magnetic field is applied at the same time, a major change of its impedance is occurred. The aim of this paper is to investigate the influence of low frequency (1KHz-12KHz) ac current and the applied magnetic field on an amorphous magnetic wire (Co68Fe4.35Si12.5B15) without glass coating. For this purpose an experimental configuration has been setup, based on a Wheatstone bridge which receives an ac input signal from a frequency generator. The output is connected to the amorphous wire wrapped with a coil supplied by a dc voltage for the generation of the magnetic field. The output voltage pulse is measured for two cases a) The value of ac frequency is changing while the value of dc voltage applied to the coil remains constant (the magnetic field remains unchanged) and b) the magnetic field is changing while the ac frequency remains constant to a predefined value. Experimental results of the first scenario showed that when the frequency is altered a non-linear increase of the ac signal is observed at the output which shows an increase of the GMI effect and is related to the non-linearity of the wire’s permeability. For the second scenario the results showed an increase of the output signal offset (voltage) which also indicates an increase of the GMI effect.

Quantitative Research on Cracks in Pipe Based on Magnetic Field Response Method of Eddy Current Testing

2021 ◽  
Vol 36 (1) ◽  
pp. 99-107
Author(s):  
Feng Jiang ◽  
Shulin Liu ◽  
Li Tao
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Quantitative Research ◽  
Three Dimensional ◽  
Impedance Analysis ◽  
Eddy Current Testing ◽  
Element Analysis ◽  
Defect Parameter ◽  
Current Testing ◽  
The Magnetic Field

The quantitative evaluation of defects in eddy current testing is of great significance. Impedance analysis, as a traditional method, is adopted to determine defects in the conductor, however, it is not able to depict the shape, size and location of defects quantitatively. In order to obtain more obvious characteristic quantities and improve the ability of eddy current testing to detect defects, the study of cracks in metal pipes is carried out by utilizing the analysis method of three-dimensional magnetic field in present paper. The magnetic field components in the space near the crack are calculated numerically by using finite element analysis. The simulation results confirm that the monitoring of the crack change can be achieved by measuring the magnetic field at the arrangement positions. Besides, the quantitative relationships between the shape, length of the crack and the magnetic field components around the metal pipe are obtained. The results show that the axial and radial magnetic induction intensities are affected more significantly by the cross-section area of the crack. Bz demonstrates obvious advantages in analyzing quantitatively crack circumference length. Therefore, the response signal in the three-dimensional direction of the magnetic field gets to intuitively reflect the change of the defect parameter, which proves the effectiveness and practicability of this method.

Visualization of the Magnetic Field Distribution for a Direct Current by Using the Magneto-optical Effect

2016 ◽  
Vol 66 (2) ◽  
pp. 231-234
Author(s):  
Sunghoon JEON ◽  
Shant ARAKELYAN ◽  
Yeonsub LEE ◽  
Yongjae KIM ◽  
Hyeji HAN ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Direct Current ◽  
Magnetic Field Distribution ◽  
Optical Effect ◽  
Magneto Optical Effect ◽  
The Magnetic Field

A Non-Contacted Magnetic Sensor with Direction Memory Based on Biot-Savart Theory

2014 ◽  
Vol 487 ◽  
pp. 606-610
Author(s):  
Hui Lue Jiang ◽  
Bo Liu ◽  
Chuan Dao Liu ◽  
Jun Li Liu
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Magnetic Sensor ◽  
Drop Out ◽  
Operating Characteristics ◽  
Reed Switch ◽  
Principle Of Superposition ◽  
Response Curves ◽  
The Magnetic Field

Magnetic sensor with direction memory can be used to control the motion direction. Based on Biot-Savart theory, the magnetic field distribution expression of a bar-type in external space is derived, and the superposition distribution of both inner and outer magnet is directed by the principle of superposition, which can be used to quantitatively describe the magnetic distribution formed by inner and outer magnet, and accurately scope the effective field. According to the operating characteristics of the magnetic reed switch with different value of pull-in and drop-out, by a proper detecting distance to ensure the magnetic field strength value of inner magnet at magnetic reed switch greater than pull-in value and less than drop-out value to make magnetic reed switch maintaining the original state when outer magnet leaving. Meanwhile, by a proper detecting distance to ensure the superinposed magnetic field strength value greater than pull-in value in the forward direction, and less than drop-out value in backward direction. Calculation of response curves show the impacts of magnet size, response intensity and detecting distance variation on the sensor.

Magnetic Generator with Automatic Gain Regulation in a Wireless Tracking System for a Capsule Endoscope

2013 ◽  
Vol 401-403 ◽  
pp. 1393-1396
Author(s):  
Xu Dong Guo ◽  
Chao Ruan ◽  
Bin Ge ◽  
Rong Guo Yan ◽  
Ying Liu
Keyword(s):  
Magnetic Field ◽  
Signal To Noise Ratio ◽  
Tracking System ◽  
Reference Value ◽  
Digital Signal ◽  
Measuring Method ◽  
Magnetic Sensor ◽  
Capsule Endoscope ◽  
The Magnetic Field ◽  
Magnetic Generator

To track a capsule endoscope, a novel measuring method based on alternating magnetic field is presented. The signal-to-noise ratio of the magnetic sensor decreases sharply with the increasing tracking distance. Thus, a magnetic generator with automatic gain regulation is designed to improve the localization precision. It is composed of a microcontroller, a DA converter, a timer, a waveform synthesis circuit, a power amplifier, a sequence control circuit and excitation coils. First, the wireless magnetic sensor measures the strength of the magnetic field produced by the magnetic generator. Via radio frequency communication, the measured result is feedback to the comparator of the microcontroller. According to a deviation obtained by comparing the measured results with the reference value, the microcontroller outputs a digital signal to the DA converter to control the magnitude of the exciting current. The prototype of the system was developed and the experiment was performed. The experiment shows that the magnetic field generator can automatically adjust the strength of the exciting signal.

Twelve-Position Calibrating Method without North Using for Three-Axis Magnetic Sensor

2011 ◽  
Vol 383-390 ◽  
pp. 5082-5087
Author(s):  
Ding Li ◽  
Song Lin Wo ◽  
Xiong Zhu Bu
Keyword(s):  
Magnetic Field ◽  
Scale Factor ◽  
Magnetic Sensor ◽  
Alignment Error ◽  
Natural Conditions ◽  
The Magnetic Field ◽  
Iron Interference

In allusion to the compensation of environmental magnetic field for using three-axis magnetic sensor, a twelve-position calibrating method without north is designed. The equations of three-axis bias, scale factor error and install alignment error are deduced in the proposed method which is totally based on the magnetic field of up direction. According to the effect of hard iron and soft iron is equaled to the variation of three-axis bias, scale factor error and install alignment error, comparison experiments are completed in natural conditions and in conditions that the effect of hard iron and soft iron is artificially imposed. The experiment shows that this method can solve the compensation of hard iron and soft iron interference effectively for the application of up direction tumbling test.

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