Diamagnetic particle focusing using ferromicrofluidics with a single magnet

Liang, Litao; Xuan, Xiangchun

doi:10.1007/s10404-012-1003-x

Cited by 64 publications

(55 citation statements)

References 40 publications

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“…Various manipulation techniques have already been proposed and developed to focus particles in microfluidics, such as dielectrophoresis [4][5], magnetophoresis [6][7] and acoustophoresis [8][9].…”

Section: Introductionmentioning

confidence: 99%

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Zhang

et al. 2013

J. Micromech. Microeng.

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G. (2013). Inertial focusing in a straight channel with asymmetrical expansion-contraction cavity arrays using two secondary flows. Journal of Micromechanics and Microengineering, 23 (8), 1-13. Inertial focusing in a straight channel with asymmetrical expansioncontraction cavity arrays using two secondary flows AbstractThe focusing of particles has a variety of applications in industry and biomedicine, including wastewater purification, fermentation filtration, and pathogen detection in flow cytometry, etc. In this paper a novel inertial microfluidic device using two secondary flows to focus particles is presented. The geometry of the proposed microfluidic channel is a simple straight channel with asymmetrically patterned triangular expansion-contraction cavity arrays. Three different focusing patterns were observed under different flow conditions: (1) a single focusing streak on the cavity side; (2) double focusing streaks on both sides; (3) half of the particles were focused on the opposite side of the cavity, while the other particles were trapped by a horizontal vortex in the cavity. The focusing performance was studied comprehensively up to flow rates of 700 μl min−1. The focusing mechanism was investigated by analysing the balance of forces between the inertial lift forces and secondary flow drag in the cross section. The influence of particle size and cavity geometry on the focusing performance was also studied. The experimental results showed that more precise focusing could be obtained with large particles, some of which even showed a single-particle focusing streak in the horizontal plane. Meanwhile, the focusing patterns and their working conditions could be adjusted by the geometry of the cavity. This novel inertial microfluidic device could offer a continuous, sheathless, and high-throughput performance, which can be potentially applied to high-speed flow cytometry or the extraction of blood cells. (1) single focusing streak on cavity side; (2) double focusing streaks on both sides; (3) half of particles focused on the opposite side of cavity, and other particles trapped by horizontal vortex in cavity. The focusing performance was studied comprehensively up to the flow rates of 700 µl min -1 . The focusing mechanism was investigated by analyzing force balance between inertial lift forces and secondary flow drag in the cross section.The influence of particle size and cavity geometry on the focusing performance was also studied. Experimental results showed that a more pronounced focusing performance can be obtained with large particles, which even showed a single-particle focusing streak in horizontal plane. Meanwhile, focusing patterns and their working conditions were adjustable by the geometry of cavity. The novel inertial microfluidic device was capable of offering a continuous, sheathless, and high-throughput performance, which can be potentially applied to highspeed flow cytometry or extraction of blood cells.

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Section: Introductionmentioning

confidence: 99%

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Zhang

et al. 2013

J. Micromech. Microeng.

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“…This is a consequence of positive magnetophoresis, which is astonishing because polystyrene particles have been previously found to behave diamagnetic in ferrofluids by multiple research groups, [32][33][34][35][36][37] including ours. 30,38,39 Such a counterintuition phenomenon becomes much more obvious in Figure 3(b), where the particle mixture migrates in a focused stream adjacent to the channel sidewall nearer to the magnet as a result of the positive magnetophoretic deflection. We speculate that these observed "pseudomagnetic" polystyrene particles are formed due to the attachment of magnetic nanoparticles (the content of the suspending ferrofluid) onto their surfaces, which has been reported in a recent experiment.…”

Section: Resultsmentioning

confidence: 98%

“…28 One neodymium-iron-boron (NdFeB) permanent magnet (B221, 1/8 00 Â 1/8 00 Â 1/16 00 , K&J Magnetics) was embedded in PDMS using the approach we developed earlier. 29,30 It is 600 lm away from the channel edge of the U turn and 1.5 mm from the straight section connecting to the inlet reservoir. Its magnetization direction (through the 1/ 16 00 thickness) is normal to the branches of the U-turn.…”

Section: Separation Mechanismmentioning

confidence: 99%

Continuous sheath-free magnetic separation of particles in a U-shaped microchannel

Liang¹,

Xuan²

2012

Biomicrofluidics

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Particle separation is important to many chemical and biomedical applications. Magnetic field-induced particle separation is simple, cheap, and free of fluid heating issues that accompany electric, acoustic, and optical methods. We develop herein a novel microfluidic approach to continuous sheath-free magnetic separation of particles. This approach exploits the negative or positive magnetophoretic deflection to focus and separate particles in the two branches of a U-shaped microchannel, respectively. It is applicable to both magnetic and diamagnetic particle separations, and is demonstrated through the sorting of 5 lm and 15 lm polystyrene particles suspended in a dilute ferrofluid. V C 2012 American Institute of Physics. [http://dx

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“…Due to the ease of process and possibility of embedding the magnets into the device, most widely used material is PDMS [48,64,98,99,65,[100][101][102]. Other materials are also used in this method such as PMMA [66] and silica [76].…”

Section: Materials and Fabricationmentioning

confidence: 99%

Microfluidic bio-particle manipulation for biotechnology

Çetin

Özer

Solmaz

2014

Biochemical Engineering Journal

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a b s t r a c tMicrofluidics and lab-on-a-chip technology offers unique advantages for the next generation devices for diagnostic therapeutic applications. For chemical, biological and biomedical analysis in microfluidic systems, there are some fundamental operations such as separation, focusing, filtering, concentration, trapping, detection, sorting, counting, washing, lysis of bio-particles, and PCR-like reactions. The combination of these operations led to the complete analysis systems for specific applications. Manipulation of the bio-particles is the key ingredient for these applications. Therefore, microfluidic bio-particle manipulation has attracted a significant attention from the academic community. Considering the size of the bio-particles and the throughput of the practical applications, manipulation of the bio-particles is a challenging problem. Different techniques are available for the manipulation of bio-particles in microfluidic systems. In this review, some of the techniques for the manipulation of bio-particles; namely hydrodynamic based, electrokinetic-based, acoustic-based, magnetic-based and optical-based methods have been discussed. The comparison of different techniques and the recent applications regarding the microfluidic bio-particle manipulation for different biotechnology applications are presented. Finally, challenges and the future research directions for microfluidic bio-particle manipulation are addressed.

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Diamagnetic particle focusing using ferromicrofluidics with a single magnet

Cited by 64 publications

References 40 publications

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Continuous sheath-free magnetic separation of particles in a U-shaped microchannel

Microfluidic bio-particle manipulation for biotechnology

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