Construction of a Magnetic Biosensor for Pathogen Detection

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Yuanpeng Li ◽  
Marlene Castro ◽  
Hyungsoon Im ◽  
Xiaofeng Yao ◽  
Sang-Hyun Oh ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Giant Magnetoresistance ◽  
Pathogen Detection ◽  
Gold Surface ◽  
Thiol Group ◽  
Microfluidic System ◽  
Microfluidic Channels ◽  
Resistance Change ◽  
Gmr Sensors ◽  
Gmr Sensor

Current methods for pathogen detection require days before a result is available, while biosensors offer the advantage of quick, on the spot results. In this project we present the proof of concept of a biosensor that uses giant magnetoresistance (GMR) sensors and a microfluidic system. The bioprobe consists of a 30 bp oligonucleotide, 5′ functionalized with a thiol group (T-DNA30) immobilized on a gold surface. Hybridization was tested with a 5′-biotinylated oligonucleotide complementary to T-DNA30 to which Streptavidin-R-Phycoerythrin was attached later. The difference in fluorescence between the target sample and control samples was observed using a scanning laser confocal fluorescence microscope. The GMR device consists of an Ir0.8Mn0.2∕Co0.9Fe0.1∕Cu∕Co0.9Fe0.1∕Ni0.82Fe0.12 multilayer structure. Magnetic nanoparticles were deposited directly on the surface of the GMR sensors. An external magnetic field was employed to polarize the nanoparticles, which can then be detected by comparing the resistance change loops of the GMR sensors before and after their deposition. A transparent elastomer, polydimethylsiloxane (PDMS), was used for the microfluidic system. The system comprises two microfluidic channels separated by a 200μm PDMS wall. The channel width is 200μm and its height 100μm. The PDMS channel was permanently bonded to the SiO2 surface of the GMR sensor. The integrated biosensor will immobilize thiolated DNA on the gold surface below which the GMR device is located. For hybridization, biotinylated DNA will be used. Finally, magnetic nanoparticles, coated with streptavidin will be attached to the hybridized DNA and detected by the GMR device.

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.

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 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.

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.

Numerical analysis of capture and isolation of magnetic nanoparticles in microfluidic system

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840075 ◽  
Author(s):  
Jianjiang Guo ◽  
Yanfei Wang ◽  
Ziqi Xue ◽  
Hui Xia ◽  
Ning Yang ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Numerical Analysis ◽  
Magnetic Nanoparticle ◽  
Microfluidic Channel ◽  
Microfluidic System ◽  
Microfluidic Channels ◽  
Optimal Parameters ◽  
Magnetic Pole ◽  
System A ◽  
Simulation Results

Rapid capturing and isolation of magnetic nanoparticles is critical for microfluidic biodetection system. A numerical model based on multiphysics coupled-field finite-element method is developed for evaluating the capture and segregation of magnetic nanoparticles in microfluidic channel. The model consists of microfluidic channels surrounded by four electromagnets changed periodically. The trajectories and trapping efficiencies are numerically analyzed for multiple magnetic nanoparticles released in microfluidic channel. Simulation results showed that magnetic pole current, inlet velocity and diameter of magnetic nanoparticles have an impact on the capture efficiency of magnetic nanoparticle. Thus, the model with the optimal parameters can reasonably predict and evaluate completely trapping of 180 nm magnetic nanoparticles in the simulation. The numerical analysis will encouraging for the design and development of new microfluidic bioseparation and detection microsystems.

Biosensor Based on Giant Magnetoresistance Material

2012 ◽  
pp. 107-122 ◽  
Author(s):  
Mitra Djamal ◽  
Ramli ◽  
Yulkifli ◽  
Suprijadi ◽  
Khairurrijal
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.

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 Molecular bridge-mediated ultralow-power gas sensing

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Aishwaryadev Banerjee ◽  
Shakir-Ul Haque Khan ◽  
Samuel Broadbent ◽  
Ashrafuzzaman Bulbul ◽  
Kyeong Heon Kim ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Electron Tunneling ◽  
Gold Surface ◽  
Gold Electrodes ◽  
Self Assembled Monolayer ◽  
Output Resistance ◽  
Resistance Change ◽  
Ultralow Power ◽  
Linker Molecules ◽  
Molecular Bridge

AbstractWe report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps. The gas-sensing nanogap device consists of a pair of vertically stacked gold electrodes separated by an insulating 6 nm spacer (~1.5 nm of sputtered α-Si and ~4.5 nm ALD SiO2), which is notched ~10 nm into the stack between the gold electrodes. The exposed gold surface is functionalized with a self-assembled monolayer (SAM) of conjugated thiol linker molecules. When the device is exposed to a target gas (1,5-diaminopentane), the SAM layer electrostatically captures the target gas molecules, forming a molecular bridge across the nanogap. The gas capture lowers the barrier potential for electron tunneling across the notched edge region, from ~5 eV to ~0.9 eV and establishes additional conducting paths for charge transport between the gold electrodes, leading to a substantial decrease in junction resistance. We demonstrated an output resistance change of >108 times upon exposure to 80 ppm diamine target gas as well as ultralow standby power consumption of <15 pW, confirming electron tunneling through molecular bridges for ultralow-power gas sensing.

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