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 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.

scholarly journals Evaluation of In-Flow Magnetoresistive Chip Cell—Counter as a Diagnostic Tool

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 105 ◽  
Author(s):  
Manon Giraud ◽  
François-Damien Delapierre ◽  
Anne Wijkhuisen ◽  
Pierre Bonville ◽  
Mathieu Thévenin ◽  
...  
Keyword(s):  
Giant Magnetoresistance ◽  
Limit Of Detection ◽  
Malignant Cell ◽  
Elisa Test ◽  
Great Sensitivity ◽  
Actual System ◽  
Whole Cells ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Sensor Detection

Inexpensive simple medical devices allowing fast and reliable counting of whole cells are of interest for diagnosis and treatment monitoring. Magnetic-based labs on a chip are one of the possibilities currently studied to address this issue. Giant magnetoresistance (GMR) sensors offer both great sensitivity and device integrability with microfluidics and electronics. When used on a dynamic system, GMR-based biochips are able to detect magnetically labeled individual cells. In this article, a rigorous evaluation of the main characteristics of this magnetic medical device (specificity, sensitivity, time of use and variability) are presented and compared to those of both an ELISA test and a conventional flow cytometer, using an eukaryotic malignant cell line model in physiological conditions (NS1 murine cells in phosphate buffer saline). We describe a proof of specificity of a GMR sensor detection of magnetically labeled cells. The limit of detection of the actual system was shown to be similar to the ELISA one and 10 times higher than the cytometer one.

Biosensor Based on Giant Magnetoresistance Material

2010 ◽  
Vol 1 (3) ◽  
pp. 1-15 ◽  
Author(s):  
Mitra Djamal
Keyword(s):  
Giant Magnetoresistance ◽  
Large Scale ◽  
Single Chip ◽  
Biomolecule Detection ◽  
Novel Approach ◽  
Large Scale Integration ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Scale Integration ◽  
The Magnetic Field

In recent years, giant magnetoresistance (GMR) sensors have shown a great potential as sensing elements for biomolecule detection. The resistance of a GMR sensor changes with the magnetic field applied to the sensor, so that a magnetically labeled biomolecule can induce a signal. Compared with the traditional optical detection that is widely used in biomedicine, GMR sensors are more sensitive, portable, and give a fully electronic readout. In addition, GMR sensors are inexpensive and the fabrication is compatible with the current VLSI (Very Large Scale Integration) technology. In this regard, GMR sensors can be easily integrated with electronics and microfluidics to detect many different analytes on a single chip. In this article, the authors demonstrate a comprehensive review on a novel approach in biosensors based on GMR material.

Low-frequency magnetoresistive eddy-current sensors for NDE of aging aircraft

1998 ◽  
Author(s):  
Eric S. Boltz ◽  
D. W. Cutler ◽  
Timothy C. Tiernan
Keyword(s):  
Eddy Current ◽  
Low Frequency ◽  
Aging Aircraft ◽  
Current Sensors

Research on Magnetoelectric Seismometer's Low Frequency Extension Technology

2014 ◽  
Vol 664 ◽  
pp. 268-273
Author(s):  
Yun Tian Teng ◽  
Xing Xing Hu ◽  
Hong Ya Lu
Keyword(s):  
Frequency Response ◽  
Low Cost ◽  
Low Frequency ◽  
High Sensitivity ◽  
Inertial Mass ◽  
Negative Resistance ◽  
Low Noise ◽  
Corner Frequency ◽  
Filter Method ◽  
High Frequency Response

Magnetoelectric seismometer has many outstanding features, such as low cost, small size, light weight, high sensitivity, low noise, good high frequency response, and reliable operation, simple set up, so these type of seismometer is widely used in several areas. However, because the structure of magnetoelectric seismometer (inertial mass and elastic support module), there has the material and mechanical structure limitation, so the inherent frequency is around between 5 to 30Hz, hard to be lower, hence, the low frequency characteristic is poor. To extend the seismometer's range of application, post compensation is needed. The researchers from both home and aboard proposed many different method to deal with the low frequency response of this seismometer, such as “inverse filter” method, “Lippmann” method, which uses negative resistance and feedback coil. These methods have got some results separately. In this paper, we will propose a low frequency integral method to extend the seismometer's frequency response. It is accomplished through balanced integration and high precision chips to suppress the circuit drifting and noise interference. The results from vibration table shows, after integration, the seismometer's low frequency corner frequency is extended from 2 Hz to under 0.1 Hz, the sensitivity is enhanced from 200V/m·s-1 to 400V/m·s-1.

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.

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.

Low Conductivity Material Detection Method Based on Eddy Current and GMR Sensors

2015 ◽  
Vol 742 ◽  
pp. 99-104
Author(s):  
Kai Jiang ◽  
Hua Ming Lei ◽  
Hui Zhao
Keyword(s):  
Eddy Current ◽  
Biological Tissue ◽  
Detection Method ◽  
Pedicle Screws ◽  
Material Detection ◽  
Detection Probe ◽  
Solid Foundation ◽  
Gmr Sensors ◽  
Trauma Injury ◽  
Gmr Sensor

The low conductivity material such as cancellous bone, cortical bone tissue and soft tissue is the mainly content in the spine. And the improvements on distinguishing the low conductivity material can make a contribution to the spinal fixation surgery process, and protect the patient from spine incident trauma injury during internal fixation prosthetics with implanting pedicle screws. As a result the low conductivity material detection is of great importance in biomedicine study. According to the magnetic property difference of different low conductivity material, an eddy current detection method based on GMR sensor which is proposed in this paper. Compared with coil sensor in traditional non-contact detecting system, GMR sensors have advantages of higher sensitivity, higher precision, better linearity and better stability. Based on this methods, this paper introduces a low conductivity material detection probe. Several experiments indicate that this detection method can detect the low conductivity material NaCl solution with conductivity of 0.128 S/m, whose electrical conductivity matches that of biological tissue. This results lay a solid foundation on the biological tissue detection research.

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