Micro-magnetometry for susceptibility measurement of superparamagnetic single bead

Brajalal Sinha; S. Anandakumar; Sunjong Oh; Cheolgi Kim

doi:10.1016/j.sna.2012.05.001

Micro-magnetometry for susceptibility measurement of superparamagnetic single bead

Brajalal Sinha
, S. Anandakumar
, Sunjong Oh
, Cheolgi Kim

Department of Physics and Chemistry

Chungnam National University

Research output: Contribution to journal › Article › peer-review

31 Scopus citations

Abstract

We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads ^® M-280 of 2.8 μm). The sensor arm length with an active sensing junction of 3 μm × 3 μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7 μm arm length sensor was measured to be 0.075 μV/A m ^-1 (6.0 μV/Oe) in the low field region. An average voltage change of 7.6 μV with a standard deviation of 0.26 μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.

Original language	English
Pages (from-to)	34-40
Number of pages	7
Journal	Sensors and Actuators, A: Physical
Volume	182
DOIs	https://doi.org/10.1016/j.sna.2012.05.001
State	Published - Aug 2012

Bibliographical note

Funding Information:
Dr. CheolGi Kim (M’91) is currently working as a full professor in the Department of Materials Science and Engineering at Chungnam National University, South Korea. He received his Ph.D. in physics from Korea Advanced Institute of Science and Technology in 1989. Currently he is director of the Center for NanoBioEngineering and SpinTronics, supported by the Ministry of Education, Science and Technology in Korea through the WCU program. He has vast experience in the fields of nanomagnetic materials, thin film based sensors and devices. His current research interests are nanostructured materials, spintronic sensors and devices, micro-magnetophoresis, and lab-on-a-chip systems.

Funding Information:
This research was supported by WCU program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology ( R32-20026 ).

Keywords

Magnetic beads
Micro-magnetometry
Multilayer thin films
PHR sensor
Susceptibility

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10.1016/j.sna.2012.05.001

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title = "Micro-magnetometry for susceptibility measurement of superparamagnetic single bead",

abstract = "We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads {\textregistered} M-280 of 2.8 μm). The sensor arm length with an active sensing junction of 3 μm × 3 μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7 μm arm length sensor was measured to be 0.075 μV/A m -1 (6.0 μV/Oe) in the low field region. An average voltage change of 7.6 μV with a standard deviation of 0.26 μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.",

keywords = "Magnetic beads, Micro-magnetometry, Multilayer thin films, PHR sensor, Susceptibility",

author = "Brajalal Sinha and S. Anandakumar and Sunjong Oh and Cheolgi Kim",

note = "Funding Information: Dr. CheolGi Kim (M{\textquoteright}91) is currently working as a full professor in the Department of Materials Science and Engineering at Chungnam National University, South Korea. He received his Ph.D. in physics from Korea Advanced Institute of Science and Technology in 1989. Currently he is director of the Center for NanoBioEngineering and SpinTronics, supported by the Ministry of Education, Science and Technology in Korea through the WCU program. He has vast experience in the fields of nanomagnetic materials, thin film based sensors and devices. His current research interests are nanostructured materials, spintronic sensors and devices, micro-magnetophoresis, and lab-on-a-chip systems. Funding Information: This research was supported by WCU program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology ( R32-20026 ). ",

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AU - Anandakumar, S.

AU - Oh, Sunjong

AU - Kim, Cheolgi

N1 - Funding Information: Dr. CheolGi Kim (M’91) is currently working as a full professor in the Department of Materials Science and Engineering at Chungnam National University, South Korea. He received his Ph.D. in physics from Korea Advanced Institute of Science and Technology in 1989. Currently he is director of the Center for NanoBioEngineering and SpinTronics, supported by the Ministry of Education, Science and Technology in Korea through the WCU program. He has vast experience in the fields of nanomagnetic materials, thin film based sensors and devices. His current research interests are nanostructured materials, spintronic sensors and devices, micro-magnetophoresis, and lab-on-a-chip systems. Funding Information: This research was supported by WCU program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology ( R32-20026 ).

PY - 2012/8

Y1 - 2012/8

N2 - We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads ® M-280 of 2.8 μm). The sensor arm length with an active sensing junction of 3 μm × 3 μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7 μm arm length sensor was measured to be 0.075 μV/A m -1 (6.0 μV/Oe) in the low field region. An average voltage change of 7.6 μV with a standard deviation of 0.26 μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.

AB - We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads ® M-280 of 2.8 μm). The sensor arm length with an active sensing junction of 3 μm × 3 μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7 μm arm length sensor was measured to be 0.075 μV/A m -1 (6.0 μV/Oe) in the low field region. An average voltage change of 7.6 μV with a standard deviation of 0.26 μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.

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KW - Susceptibility

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JO - Sensors and Actuators, A: Physical

JF - Sensors and Actuators, A: Physical

ER -

Micro-magnetometry for susceptibility measurement of superparamagnetic single bead

Abstract

Bibliographical note

Keywords

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