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Low-frequency noise in planar Hall effect bridge sensors
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
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2011 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 171, no 2, 212-218 p.Article in journal (Refereed) Published
Abstract [en]

The low-frequency characteristics of planar Hall effect bridge sensors are investigated as function of the sensor bias current and the applied magnetic field. The noise spectra reveal a Johnson-like spectrum at high frequencies, and a 1/f-like excess noise spectrum at lower frequencies, with a knee frequency of around 400 Hz. The 1/f-like excess noise can be described by the phenomenological Hooge equation with a Hooge parameter of γH = 0.016. The detectivity is shown to depend on the total length, width and thickness of the bridge branches. The detectivity is improved by the square root of the length increase. Moreover, the detectivity is shown to depend on the amplitude of the applied magnetic field, revealing a magnetic origin to part of the 1/f noise.

Place, publisher, year, edition, pages
Elsevier, 2011. Vol. 171, no 2, 212-218 p.
Keyword [en]
Magnetoresistance, Planar Hall effect, Low-frequency noise, Detectivity
National Category
Materials Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-163740DOI: 10.1016/j.sna.2011.09.014ISI: 000297454400022OAI: oai:DiVA.org:uu-163740DiVA: diva2:464746
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Available from: 2011-12-19 Created: 2011-12-14 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Biomolecular Recognition Based on Field Induced Magnetic Bead Dynamics
Open this publication in new window or tab >>Biomolecular Recognition Based on Field Induced Magnetic Bead Dynamics
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, three different read-out techniques for biomolecular recognition have been studied. All three techniques rely on the change in dynamic behaviour of probe functionalised magnetic beads after binding to a biomolecular target complementary to the probe.

In the first technique presented, the sample is exposed to an AC magnetic field while the response to this field is probed using a laser source and a photodetector positioned at opposite sides of the sample. Beads bound to the target entity will experience an increase in their hydrodynamic volume, and will not be able to respond as rapidly to an alternating field as free beads. Here, the target entity is either DNA coils formed by rolling circle amplification or biotinylated bovine serum albumin (bBSA). The change in dynamic behaviour is measured as a frequency dependent modulation of transmitted light. Limit of detections (LODs) of 5 pM DNA coils originating from a V. cholerae target and 100 pM of bBSA have been achieved.

In the second technique presented, the beads are magnetically transported across a probe functionalised detection area on a microchip. Beads bound to a target will be blocked from interaction with the detection area probes, whereas in the absence of a target, beads will be immobilised on the detection area. The LOD of biotin for this system proved to be in the range of 20 to 50 ng/ml.

In the third technique presented, the sample is microfluidically transported to a detection area on a microchip. The read-out is performed using a planar Hall effect bridge sensor. A sinusoidal current is applied to the bridge in one direction and the sensor output voltage is measured across the sensor in the perpendicular direction. The AC current induced bead magnetisation contributing to the sensor output will appear different for free beads compared to beads bound to a target. LODs of 500 B. globigii spores and 2 pM of V. cholerae DNA coils were achieved.

From a lab-on-a-chip point of view, all three techniques considered in this thesis show promising results with regards to sensitivity and integrability.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 94 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1193
Keyword
Magnetic biosensor, magnetic nanoparticle, DNA detection
National Category
Nano Technology Biochemistry and Molecular Biology Condensed Matter Physics
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-234302 (URN)978-91-554-9077-5 (ISBN)
Public defence
2014-12-12, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Available from: 2014-11-21 Created: 2014-10-15 Last updated: 2015-02-03

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Publisher's full texthttp://www.sciencedirect.com/science/article/pii/S0924424711005280

Authority records BETA

Persson, AndersBejhed, Rebecca SNguyen, HugoGunnarsson, KlasSvedlindh, Peter

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