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Resonance-based detection of magnetic nanoparticles and microbeads using nanopatterned ferromagnets

Resonance-based detection of magnetic nanoparticles and microbeads using nanopatterned ferromagnets
Resonance-based detection of magnetic nanoparticles and microbeads using nanopatterned ferromagnets
Biosensing with ferromagnet-based magnetoresistive devices has been dominated by electrical detection of particle-induced changes to a device’s (quasi-)static magnetic configuration. There are however potential advantages to be gained from using field dependent, high frequency resonant magnetization dynamics for magnetic particle detection. Here, we demonstrate the use of nanoconfined ferromagnetic resonances in periodically nanopatterned magnetic films for the detection of adsorbed magnetic particles having diameters ranging from 6 nm to 4???m. The nanopatterned films contain arrays of holes which appear to act as preferential adsorption sites for small particles. Hole-localized particles act in unison to shift the frequencies of the patterned layer’s ferromagnetic-resonance modes, with shift polarities determined by the localization of each mode within the nanopattern’s repeating unit cell. The same polarity shifts are observed for a large range of coverages, even when quasicontinuous particle sheets form above the hole-localized particles. For large particles, preferential adsorption no longer occurs, leading to resonance shifts with polarities that are independent of the mode localization, and amplitudes that are comparable to those seen in continuous layers. Indeed, for nanoparticles adsorbed onto a continuous layer, the particle-induced shift of the layer’s fundamental mode is up to 10 times less than that observed for nanoconfined modes in the nanopatterned systems, the low shift being induced by relatively weak fields emanating beyond the particle in the direction of the static applied field. This result highlights the importance of having particles consistently positioned in the close vicinity of confined modes.
1-12
Sushruth, Manu
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Ding, Junjia
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Duczynsky, Jeremy
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Woodward, Robert C.
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Begley, Ryan
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Fangohr, Hans
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Fuller, Rebecca O.
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Adeyeye, Adekunle O.
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Kostylev, Mikhail
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Metaxas, Peter J
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Sushruth, Manu
cfd81b5b-0dc2-41d9-bd43-e46ea58fab64
Ding, Junjia
7ee7fdc0-17c1-4f5d-b279-11b05f9600c6
Duczynsky, Jeremy
01ed0aa2-2be9-4ae7-970f-d38b0a522bcb
Woodward, Robert C.
fe722368-49b1-4f75-9c00-2a9128e0c0fd
Begley, Ryan
ad477c66-194e-49da-baff-2d3ed1b64dec
Fangohr, Hans
9b7cfab9-d5dc-45dc-947c-2eba5c81a160
Fuller, Rebecca O.
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Adeyeye, Adekunle O.
7afb3a23-5426-419d-8204-791be13b1578
Kostylev, Mikhail
987113b2-474b-4b97-a51b-51e81ed79e83
Metaxas, Peter J
70725004-2786-448f-b030-951487ef8b90

Sushruth, Manu, Ding, Junjia, Duczynsky, Jeremy, Woodward, Robert C., Begley, Ryan, Fangohr, Hans, Fuller, Rebecca O., Adeyeye, Adekunle O., Kostylev, Mikhail and Metaxas, Peter J (2016) Resonance-based detection of magnetic nanoparticles and microbeads using nanopatterned ferromagnets. Physical Review Applied, 6 (4), 1-12. (doi:10.1103/PhysRevApplied.6.044005).

Record type: Article

Abstract

Biosensing with ferromagnet-based magnetoresistive devices has been dominated by electrical detection of particle-induced changes to a device’s (quasi-)static magnetic configuration. There are however potential advantages to be gained from using field dependent, high frequency resonant magnetization dynamics for magnetic particle detection. Here, we demonstrate the use of nanoconfined ferromagnetic resonances in periodically nanopatterned magnetic films for the detection of adsorbed magnetic particles having diameters ranging from 6 nm to 4???m. The nanopatterned films contain arrays of holes which appear to act as preferential adsorption sites for small particles. Hole-localized particles act in unison to shift the frequencies of the patterned layer’s ferromagnetic-resonance modes, with shift polarities determined by the localization of each mode within the nanopattern’s repeating unit cell. The same polarity shifts are observed for a large range of coverages, even when quasicontinuous particle sheets form above the hole-localized particles. For large particles, preferential adsorption no longer occurs, leading to resonance shifts with polarities that are independent of the mode localization, and amplitudes that are comparable to those seen in continuous layers. Indeed, for nanoparticles adsorbed onto a continuous layer, the particle-induced shift of the layer’s fundamental mode is up to 10 times less than that observed for nanoconfined modes in the nanopatterned systems, the low shift being induced by relatively weak fields emanating beyond the particle in the direction of the static applied field. This result highlights the importance of having particles consistently positioned in the close vicinity of confined modes.

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1604.05835 v1 Fangohr.pdf - Accepted Manuscript
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More information

Accepted/In Press date: 28 June 2016
e-pub ahead of print date: 5 October 2016
Published date: October 2016
Organisations: Computational Engineering & Design Group

Identifiers

Local EPrints ID: 401702
URI: https://eprints.soton.ac.uk/id/eprint/401702
PURE UUID: 47653799-a4a3-478b-a1d1-88b9da9eaad9

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Date deposited: 19 Oct 2016 14:20
Last modified: 29 Nov 2018 17:31

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