A Detection System Based on Giant Magnetoresistive Sensors and High‐Moment Magnetic Nanoparticles Demonstrates Zeptomole Sensitivity: Potential for Personalized Medicine

Balasubramanian, S.; Li, Yuanpeng; Jing, Ying; Xu, Yun; Yao, Xiling; Xing, Chengguo; Wang, Jian Ping

doi:10.1002/anie.200806266

Cited by 125 publications

(71 citation statements)

References 29 publications

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“…and are employed in detecting target biomolecules by binding the probe biomolecules immobilized on the magnetic sensor surface. In the literature, the magnetic sensing bioassay research has mainly focused on improving the limits of detection [1][2][3]. The improvement of the detection limit is attributed to the detection of very weak magnetic fields generated from the small number of conjugated magnetic biolabels (e.g single bead) on the magnetic sensor surfaces [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

Kim¹,

Reddy²,

Kim³

et al. 2014

Journal of Magnetics

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In this study, we fabricate an integrated microfluidic chip with a planar Hall effect (PHE) sensor for single magnetic bead detection. The PHE sensor was constructed with a junction size of 10 µm × 10 µm using a trilayer structure of Ta(3 nm)/NiFe(10 nm)/Cu(1.2 nm)/IrMn(10 nm)/Ta(3 nm). The sensitivity of the PHE sensor was 19.86 µV/Oe. A diameter of 8.18 µm magnetic beads was used, of which the saturation magnetization was ~2.1 emu/g. The magnetic susceptibility χ of these magnetic beads was calculated to bẽ 0.14. The diluted magnetic beads solution was introduced to the microfluidic channel attributing a single bead flow and simultaneously the PHE sensor voltage was measured to be 0.35 µV. The integrated microchip was able to detect a magnetic moment of 1.98 × 10 −10 emu.

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Section: Introductionmentioning

confidence: 99%

Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

Kim¹,

Reddy²,

Kim³

et al. 2014

Journal of Magnetics

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“…The technique is intrinsically matrix-insesntive 1 , can compete with industry-standard immunoassays 4 and can be combined with magnetic separation methods 5 . The central element of a magnetic biosensor is a detector for the stray or 'fringing' magnetic fields generated by magnetised MNPs which are used to label, typically in-vitro, analytes of interest within a biological sample.…”

mentioning

confidence: 99%

“…Previously used sensors include SQuIDs 6 , Hall sensors 7 , ferromagnetic rings 8,9 and magneto-impedance devices 10 . However one of the most widely used methods is that employing magnetoresistive (MR) magnetic field sensors [1][2][3][4][5][11][12][13][14] which are typically fabricated with at least one lateral dimension on the order of 10-100 µm. An MNP is detected when its stray (or 'fringing') magnetic field modifies the quasi-static magnetic configuration in the ferromagnetic MR device.…”

mentioning

confidence: 99%

Sensing magnetic nanoparticles using nano-confined ferromagnetic resonances in a magnonic crystal

Metaxas¹,

Sushruth²,

Begley³

et al. 2015

Applied Physics Letters

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We demonstrate the use of the magnetic-field-dependence of highly spatially confined, GHz-frequency ferromagnetic resonances in a ferromagnetic nanostructure for the detection of adsorbed magnetic nanoparticles. This is achieved in a large area magnonic crystal consisting of a thin ferromagnetic film containing a periodic array of closely spaced, nano-scale anti-dots. Stray fields from nanoparticles within the anti-dots modify resonant dynamic magnetisation modes in the surrounding magnonic crystal, generating easily measurable resonance peak shifts. The shifts are comparable to the resonance linewidths for high anti-dot filling fractions with their signs and magnitudes dependent upon the modes' localisations (in agreement with micromagnetic simulation results). This is a highly encouraging result for the development of frequencybased nanoparticle detectors for high speed nano-scale biosensing.Magnetic biosensors, in which biological analytes are tagged with magnetic nanoparticles (MNPs), have excellent potential for solid-state point-of-care medical diagnostics 1-3 . The technique is intrinsically matrix-insesntive 1 , can compete with industry-standard immunoassays 4 and can be combined with magnetic separation methods 5 . The central element of a magnetic biosensor is a detector for the stray or 'fringing' magnetic fields generated by magnetised MNPs which are used to label, typically in-vitro, analytes of interest within a biological sample. Previously used sensors include SQuIDs 6 , Hall sensors 7 , ferromagnetic rings 8,9 and magneto-impedance devices 10 . However one of the most widely used methods is that employing magnetoresistive (MR) magnetic field sensors [1][2][3][4][5][11][12][13][14] which are typically fabricated with at least one

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“…This enables the use of magnetic nanoparticles (MNPs) to tag and subsequently detect biological analytes of interest reliably within a range of bodily fluids [4][5][6] . Common device setups include sandwich assays 4,7,8 , where the analyte is immobilised on the sensor surface and sandwiched between two antibodies which bind it to the sensor and the MNP used for detection ( Fig. 1(a)), and flow cytometry 9,10 , where the MNP-tagged analyte is detected as it flows through a microfluidic channel.…”

Section: Introductionmentioning

confidence: 99%

Frequency-based nanoparticle sensing over large field ranges using the ferromagnetic resonances of a magnetic nanodisc

et al. 2016

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Using finite element micromagnetic simulations, we study how resonant magnetisation dynamics in thin magnetic discs with perpendicular anisotropy are influenced by magnetostatic coupling to a magnetic nanoparticle. We identify resonant modes within the disc using direct magnetic eigenmode calculations and study how their frequencies and profiles are changed by the nanoparticle's stray magnetic field. We demonstrate that particles can generate shifts in the resonant frequency of the disc's fundamental mode which exceed resonance linewidths in recently studied spin torque oscillator devices. Importantly, it is shown that the simulated shifts can be maintained over large field ranges (here up to 1 T). This is because the resonant dynamics (the basis of nanoparticle detection here) respond directly to the nanoparticle stray field, i.e. detection does not rely on nanoparticle-induced changes to the magnetic ground state of the disk. A consequence of this is that in the case of small disc-particle separations, sensitivities to the particle are highly mode-and particle-positiondependent, with frequency shifts being maximised when the intense stray field localised directly beneath the particle can act on a large proportion of the disc's spins that are undergoing high amplitude precession.

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A Detection System Based on Giant Magnetoresistive Sensors and High‐Moment Magnetic Nanoparticles Demonstrates Zeptomole Sensitivity: Potential for Personalized Medicine

Cited by 125 publications

References 29 publications

Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

Single Magnetic Bead Detection in a Microfluidic Chip Using Planar Hall Effect Sensor

Sensing magnetic nanoparticles using nano-confined ferromagnetic resonances in a magnonic crystal

Frequency-based nanoparticle sensing over large field ranges using the ferromagnetic resonances of a magnetic nanodisc

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