Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Rapoport, Elizabeth; Beach, Geoffrey S. D.

doi:10.1103/physrevb.87.174426

Cited by 16 publications

(24 citation statements)

References 42 publications

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“…Additionally, much research interest in this area is driven by the potential for novel technological developments such as logic [1] and memory [2] devices. More recently the ability to detect [3] and manipulate [4][5][6][7][8] magnetic nanoparticles with DWs has been demonstrated with possible futures in lab-on-a-chip technologies.…”

Section: Introductionmentioning

confidence: 99%

Dynamic interaction between domain walls and nanowire vertices

et al. 2014

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The dynamic behavior of magnetic domain walls incident upon a Y-shaped junction between three nanowires is explored. Details in the micromagnetic structure of the domain wall and the local spin texture at a vertex result in a complex interaction which ultimately determines the propagation direction of the domain wall following the vertex. This interaction has been explored through both magneto-optical Kerr effect experiments and micromagnetic simulations on single-vertex structures. Differences in the micromagnetic structure of incident domain walls in the dynamic regime have a significant influence on the interaction. We observe an oscillatory path selection with increasing domain wall propagation distance preceding the vertex. Our analysis shows that this behavior originates from cyclic reversals of the transverse domain wall chirality due to Walker breakdown processes.

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Section: Introductionmentioning

confidence: 99%

Dynamic interaction between domain walls and nanowire vertices

et al. 2014

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“…Similarly, patterned disk arrays are used for the movement of micro particles, involving the applications of in‐plane and out‐of‐plane magnetic field sequences. The precise positioning through predefined magnetic tracks and 2D periodic structures was realized. Moreover, the linear motion of magnetic particles within magnetic tubes was shown.…”

Section: Introductionmentioning

confidence: 99%

A Trisymmetric Magnetic Microchip Surface for Free and Two‐Way Directional Movement of Magnetic Microbeads

Sajjad

Lage

McCord

2018

Adv Materials Inter

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it is dominated by the out-of-plane (z) stray component of the magnetic stray field gradient, denoted as dH stray,z /dz, occurring above the magnetised magnetic surface. By alteration of the external magnetic field strength and direction, the occurrence and the position of magnetic field gradients can be varied in a controlled way.Thus, using rotating magnetic fields, the manipulation and transportation of mere and labeled microbeads are realized along defined paths of discrete soft-magnetic patterns. [5][6][7][8][9][10] Similarly, patterned disk arrays are used for the movement of micro particles, [11][12][13][14][15] involving the applications of in-plane and out-of-plane magnetic field sequences. The precise positioning through predefined magnetic tracks [16][17][18][19][20][21] and 2D periodic structures [22] was realized. Moreover, the linear motion of magnetic particles within magnetic tubes [23] was shown. The sorting of microbeads populations in a fixed direction and along a magnetic track on a chip was demonstrated. [24][25][26] In all the latter cases, the particle motion takes place along a predefined axis or direction. A node structure or a switch is necessary in such structures. Limitations in efficiency of movement is another factor that affects the adaptability of magnetic chip based approaches. [27] Overall, using magnetically labeled superparamagnetic beads for selective and free or flexible lateral cell moving together with sorting has not been realized for microfluidic lab-on-chip applications.In this paper, we demonstrate a novel approach for the realization of free lateral and selective motion and, thus, sorting of different ensembles of microbeads by utilizing a broken symmetry in stray field gradients due to symmetrically and asymmetrically applied external magnetic fields. Temporally and spatially tuning of the stray field gradients at corners and along edges in periodically arranged soft-magnetic micromagnets facilitates the individual movement of dissimilar microbead populations. By applying square wave modulated externally applied magnetic field components, we realize the guided motion of microbeads along selectable microcorridors across arrays of magnetic elements. Choosing the proper external magnetic field parameters, we achieve bidirectional propulsion and separation, depending on the size of the microbeads. The areas with 2D periodic structures enable multidirectional and microbead selective transportation of mixed-sized microbead ensembles at a single bead level. The presented dynamical approach of selective bead motion and bead separation paves a new way for the development of alternative magnetic field configurable micromagnetic lab-on-chip devices.The guidance of labeled microcarriers in microfluidic environments is a prerequisite to the development of magnetic pattern assisted lab-on-chip technology. Square wave modulations of in-plane applied magnetic fields enable the forward and backward locomotion of superparamagnetic microspheres on discrete hexagonally arranged ferromagn...

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“…Microscale electromagnets 25 – 28 and two-dimensional arrays of soft magnetic microstructures 14 , 16 , 29 – 32 have been used to transport microbead ensembles 26 , 29 , 30 and even individual beads 14 , 16 , 31 , 32 . Extended magnetic track structures have also been introduced, which allow for one-dimensional transport and the construction of multiplexed networks 11 , 15 , 17 – 23 , 33 – 37 . These transport systems are based on periodic, nonuniform magnetic textures or propagating magnetic domain walls (DWs) that lead to either stepped or continuously translating potential energy wells that can transport individual magnetic particles.…”

Section: Introductionmentioning

confidence: 99%

“…These transport systems are based on periodic, nonuniform magnetic textures or propagating magnetic domain walls (DWs) that lead to either stepped or continuously translating potential energy wells that can transport individual magnetic particles. The strong, localized stray field 38 from domain walls in submicrometer tracks can trap individual superparamagnetic (SPM) beads with forces up to hundreds of pN 15 , 18 , 22 , 23 , 33 , 39 . As DWs can be readily driven along a track by a magnetic field, 40 – 43 spin-polarized electric current 44 , 45 , or electric fields 46 they can serve as mobile magnetic traps for single bead transport along a predefined path.…”

Section: Introductionmentioning

confidence: 99%

“…Designs in which a DW is continuously translated while continuously binding a magnetic particle have some advantages compared to systems in which beads jump stepwise from one localized stray field source to another: higher transport speeds can be obtained by eliminating the diffusive transport step between binding sites, and particles can be more robust in, e.g., fluid flows since the particles are always magnetically bound during transport. Recently, a curved track architecture was introduced in which a rotating magnetic field can continuously drive magnetic domain walls along a track at a speed set by the field rotation rate, and that very high particle transport speeds in excess of 1000 μm/s can be obtained 22 , 23 .…”

Section: Introductionmentioning

confidence: 99%

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Architecture for Directed Transport of Superparamagnetic Microbeads in a Magnetic Domain Wall Routing Network

Rapoport

Beach

2017

Sci Rep

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Directed transport of biological species across the surface of a substrate is essential for realizing lab-on-chip technologies. Approaches that utilize localized magnetic fields to manipulate magnetic particles carrying biological entities are attractive owing to their sensitivity, selectivity, and minimally disruptive impact on biomaterials. Magnetic domain walls in magnetic tracks produce strong localized fields and can be used to capture, transport, and detect individual superparamagnetic microbeads. The dynamics of magnetic microbead transport by domain walls has been well studied. However, demonstration of more complex functions such as selective motion and sorting using continuously driven domain walls in contiguous magnetic tracks is lacking. Here, a junction architecture is introduced that allows for branching networks in which superparamagnetic microbeads can be routed along dynamically-selected paths by a combination of rotating in-plane field for translation, and a pulsed out-of-plane field for path selection. Moreover, experiments and modeling show that the select-field amplitude is bead-size dependent, which allows for digital sorting of multiple bead populations using automated field sequences. This work provides a simple means to implement complex routing networks and selective transport functionalities in chip-based devices using magnetic domain wall conduits.

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Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Cited by 16 publications

References 42 publications

Dynamic interaction between domain walls and nanowire vertices

Dynamic interaction between domain walls and nanowire vertices

A Trisymmetric Magnetic Microchip Surface for Free and Two‐Way Directional Movement of Magnetic Microbeads

Architecture for Directed Transport of Superparamagnetic Microbeads in a Magnetic Domain Wall Routing Network

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