scholarly journals Quasi-Static Current Measurement with Field-Modulated Spin-Valve GMR Sensors

Sensors ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 1882
Author(s):  
Jen-Tzong Jeng ◽  
Xuan-Thang Trinh ◽  
Chih-Hsien Hung ◽  
Chih-Cheng Lu
Keyword(s):  
Spin Valve ◽  
High Sensitivity ◽  
Current Measurement ◽  
Linear Range ◽  
Current Sensing ◽  
Measured Current ◽  
Ferrite Ring ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Ring Core

A non-contact current measurement device comprised of a GMR sensor and a ferrite ring core was investigated. The sensor chip employed a high-sensitivity spin-valve full-bridge GMR sensor of which the direct output has non-negligible hysteresis and a limited linear range. By applying an AC modulation current to modulate the output of the GMR sensor, the hysteresis was reduced, and the linear range was over ±0.5 A. The resolution for DC and quasi-static current measurement was 0.1 mA at a 10 Hz bandwidth. The output in proportion to the measured current was obtained either by demodulating the current-sensitive AC signal or by employing the filtered output of the intrinsically nonlinear spin-valve response. The proposed current sensing scheme is suitable for quasi-static current measurement from DC to over 100 Hz.

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.

Two-step thinning fabrication of giant magnetoresistance sensors for flexible applications

2014 ◽  
Vol 28 (10) ◽  
pp. 1450081 ◽  
Author(s):  
Cong Yin ◽  
Dan Xie ◽  
Jian-Long Xu ◽  
Tian-Ling Ren
Keyword(s):  
Inductively Coupled Plasma ◽  
Giant Magnetoresistance ◽  
Ion Beam ◽  
Spin Valve ◽  
Mechanical Damage ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Gmr Sensors ◽  
Flexible Applications ◽  
Gmr Sensor

Spin valve giant magnetoresistance (GMR) sensors were prepared by a two-step thinning method combining grind thinning and inductively coupled plasma (ICP) etching together. The fabrication processes of front GMR sensors and backside ICP etching were described in detail. Magnetoresistance ratio of about 4.24% and coercive field of approximately 11 Oe were obtained in a tested bendable GMR sensor. The variations of the magnetic property in GMR sensors were explained mainly from the temperature, ion beam damage and mechanical damage generated by the fabrication process.

scholarly journals Time-Multiplexed Self-Powered Wireless Current Sensor for Power Transmission Lines

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1561
Author(s):  
Hao Chen ◽  
Zhongnan Qian ◽  
Chengyin Liu ◽  
Jiande Wu ◽  
Wuhua Li ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Transmission Line ◽  
Transmission Lines ◽  
Power Transmission ◽  
Current Measurement ◽  
Current Sensor ◽  
Power Transmission Line ◽  
Power Transmission Lines ◽  
Current Sensing ◽  
Self Powered

Current measurement is a key part of the monitoring system for power transmission lines. Compared with the conventional current sensor, the distributed, self-powered and contactless current sensor has great advantages of safety and reliability. By integrating the current sensing function and the energy harvesting function of current transformer (CT), a time-multiplexed self-powered wireless sensor that can measure the power transmission line current is presented in this paper. Two operating modes of CT, including current sensing mode and energy harvesting mode, are analyzed in detail. Through the design of mode-switching circuit, harvesting circuit and measurement circuit are isolated using only one CT secondary coil, which eliminates the interference between energy harvesting and current measurement. Thus, the accurate measurement in the current sensing mode and the maximum energy collection in the energy harvesting mode are both realized, all of which simplify the online power transmission line monitoring. The designed time-multiplexed working mode allows the sensor to work at a lower transmission line current, at the expense of a lower working frequency. Finally, the proposed sensor is verified by experiments.

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.

Cds nanocrystal enhanced TiO2photoelectrochemical aptasensor for sensitive detection of cytochrome c

2021 ◽  
Vol 11 (11) ◽  
pp. 1774-1780
Author(s):  
Shanji Fan ◽  
Hong Huang ◽  
Hong Chen ◽  
Jiachi Xu ◽  
Zecheng Hu ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Limit Of Detection ◽  
Specific Binding ◽  
High Sensitivity ◽  
High Specificity ◽  
Linear Range ◽  
Current Intensity ◽  
Sensitive Detection ◽  
Layer Adsorption ◽  
Ionic Layer

A CdS nanocrystal enhanced TiO2 nanotubes (CdS@TiO2 NATs) photoelectrode was prepared via successive ionic layer adsorption and reaction (SILAR) of CdS on the surface of TiO2 NATs. A HS-aptamer owing a specific binding toward cytochrome c was modified onto the CdS@TiO2 NATs, which resulting a decrease in the photoelectrical current intensity. Cytochrome c is therefore quantified based on the decrease in photoelectrical current. High specificity and high sensitivity were obtained with a linear range from 3 pM to 80 nM, and a limit of detection of 2.53 pM.

Thermal Effects and Self-Heating Time Constant for GMR Recording Heads

2003 ◽  
Author(s):  
Lydia Baril ◽  
Erhard Schreck ◽  
Al Wallash
Keyword(s):  
Time Constant ◽  
Heating Time ◽  
Heat Sources ◽  
Resistance Change ◽  
Self Heating ◽  
Recording Heads ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Short Time ◽  
Current Transients

An understanding of the temperature of the GMR reader element used in disk drives during operating and non-operating condition is critical to optimize its performance. Self-heating and/or external heat sources will cause an increase in the temperature of the GMR sensor. In this work we concentrate on the self-heating effect due to bias current. Experiments that monitored the resistance change during very short current pulses showed that state-of-the-art GMR sensors have an extremely short time-constant that is less than 2 ns. This work is applicable to the current transients that the GMR head experiences during electrical crosstalk, electrostatic discharge and thermal asperities.

scholarly journals Noise Characterization of Vortex-State GMR Sensors with Different Free Layer Thicknesses

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1013
Author(s):  
Herbert Weitensfelder ◽  
Hubert Brueckl ◽  
Armin Satz ◽  
Dieter Suess
Keyword(s):  
Spin Valve ◽  
Low Frequency ◽  
Vortex State ◽  
Frequency Noise ◽  
Free Layer ◽  
Low Frequencies ◽  
Gmr Sensors ◽  
Noise Characterization ◽  
Higher Sensitivity

The spin valve principle is the most prominent sensor design among giant- (GMR) and tunneling (TMR) magnetoresistive sensors. A new sensor concept with a disk shaped free layer enables the formation of a flux-closed vortex magnetization state if a certain relation of thickness to diameter is given. The low frequency noise of current-in-plane GMR sensing elements with different free layer thicknesses at different external field strengths has been measured. The measurements of the 1/f noise in external fields enabled a separation of magnetic and electric noise contributions. It has been shown that while the sensitivity is increasing with a decreasing element thickness, the pink noise contribution is increasing too. Still the detection limit at low frequencies is better in thinner free layer elements due to the higher sensitivity.

High Sensitivity Spin Valve Sensors With AF Coupled Flux Guides

2008 ◽  
Vol 44 (11) ◽  
pp. 2472-2474 ◽  
Author(s):  
I.G. Trindade ◽  
J. Teixeira ◽  
R. Fermento ◽  
J.B. Sousa ◽  
S. Cardoso ◽  
...  
Keyword(s):  
Spin Valve ◽  
High Sensitivity
Sign in / Sign up

Export Citation Format

Share Document