Magnetophoresis of diamagnetic microparticles in a weak magnetic field

Zhu, Guiping; Hejiazan, Majid; Huang, Xiaoyang; Nguyen, Nam‐Trung

doi:10.1039/c4lc00885e

Cited by 35 publications

(29 citation statements)

References 58 publications

(78 reference statements)

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“…Also neglected are the dipole-dipole interactions among the same type or different types of particles in a magnetic field. Such a treatment of particle-fluid and particle-particle interactions has been demonstrated reasonable in previous theoretical studies from the groups of Mao et al, 28,32,37,40,42 Nguyen et al, 41 and Xuan et al 30,31,33,36,39 as long as the particle and ferrofluid concentrations are both low. These conditions are fulfilled in the current work because of the use of a dilute particle suspension in a diluted ferrofluid.…”

Section: Simulationmentioning

confidence: 83%

“…[28][29][30][31][32][33][36][37][38][39][40][41]47 As such, the steady-state flow field in the T-shaped microchannel, u, is governed by the conventional continuity and Navier-Stokes equations…”

Section: Flow Field and Concentration Field Of The Ferrofluidmentioning

confidence: 99%

“…[25][26][27] Diamagnetic particles must be re-suspended in magnetic media like ferrofluids [28][29][30][31][32][33] and paramagnetic solutions, 34,35 so that they experience negative magnetophoresis and are repelled away from the magnetic source. [36][37][38][39][40][41][42] While magnetic particle trapping has been demonstrated with single magnets placed on one side of the particle flowing microchannel, 23-27 diamagnetic particle trapping can only take place stably with one or multiple pair(s) of magnets arranged on both sides of the channel. [43][44][45][46][47] The strong attractive or repulsive force between the pair(s) of magnets often renders it difficult to align the magnets and place them close enough to the particle flowing channel.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet

Zhou

Kumar

et al. 2015

Biomicrofluidics

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Trapping and preconcentrating particles and cells for enhanced detection and analysis are often essential in many chemical and biological applications. Existing methods for diamagnetic particle trapping require the placement of one or multiple pairs of magnets nearby the particle flowing channel. The strong attractive or repulsive force between the magnets makes it difficult to align and place them close enough to the channel, which not only complicates the device fabrication but also restricts the particle trapping performance. This work demonstrates for the first time the use of a single permanent magnet to simultaneously trap diamagnetic and magnetic particles in ferrofluid flows through a T-shaped microchannel. The two types of particles are preconcentrated to distinct locations of the T-junction due to the induced negative and positive magnetophoretic motions, respectively. Moreover, they can be sequentially released from their respective trapping spots by simply increasing the ferrofluid flow rate. In addition, a three-dimensional numerical model is developed, which predicts with a reasonable agreement the trajectories of diamagnetic and magnetic particles as well as the buildup of ferrofluid nanoparticles.

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Section: Simulationmentioning

confidence: 83%

Section: Flow Field and Concentration Field Of The Ferrofluidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet

Zhou

Kumar

et al. 2015

Biomicrofluidics

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show abstract

“…We further developed a new device design that significantly reduces the exposure time of cells in ferrofluids, from hours to seconds, by taking advantage of the laminar flow nature of liquids in microchannels. 22, 23 The design is explained in detail in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Biocompatible and label-free separation of cancer cells from cell culture lines from white blood cells in ferrofluids

et al. 2017

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This paper reports a biocompatible and label-free cell separation method using ferrofluids that can separate a variety of low-concentration cancer cells from cell culture lines (~100 cancer cells/mL) from undiluted white blood cells, with a throughput of 1.2 mL/h and an average separation efficiency of 82.2%. The separation is based on size difference from cancer cells and white blood cells, and is conducted in a custom-made biocompatible ferrofluid that retains not only excellent short-term viabilities, but also normal proliferations of 7 commonly used cancer cell lines. A microfluidic device is designed and optimized specifically to shorten the exposure time of live cells in ferrofluids from hours to seconds, by eliminating time-consuming off-chip sample preparation and extraction steps and integrating them on-chip to achieve one-step process. As a proof-of-concept demonstration, a ferrofluid with 0.26% volume fraction was used in this microfluidic device to separate spiked cancer cells from cell lines at a concentration of ~100 cells/mL from white blood cells with a 1.2 mL/h throughput. The separation efficiencies were 80±3%, 81±5%, 82±5%, 82±4%, and 86±6% for A549 lung cancer, H1299 lung cancer, MCF-7 breast cancer, MDA-MB-231 breast cancer, and PC-3 prostate cancer cell lines, respectively. Separated cancer cells purity was between 25.3% and 28.8%. In addition, separated cancer cells from this strategy showed an average short-term viability of 94.4±1.3% and separated cells were cultured and demonstrated normal proliferation to the confluence even after the separation process. Owning to its excellent biocompatibility and label-free operation, and its ability to recover low concentration of cancer cells from white blood cells, this method could lead to a promising tool for rare cell separation.

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“…There are a variety of methods [7] to sort human sperm cells by their motility or morphology, as well as a multitude of microfluidic techniques yet to be used on sperm cells [8][9][10]. Dielectrophoresis [11] has been applied to separate mature spermatozoa from non-mature spermatogenic cells [12].…”

Section: Introductionmentioning

confidence: 99%

Supervised Learning to Predict Sperm Sorting by Magnetophoresis

2018

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Machine learning is gaining popularity in the commercial world, but its benefits are yet to be well-utilised by many in the microfluidics community. There is immense potential in bridging the gap between applied engineering and artificial intelligence as well as statistics. We illustrate this by a case study investigating the sorting of sperm cells for assisted reproduction. Slender body theory (SBT) is applied to compute the behavior of sperm subjected to magnetophoresis, with due consideration given to statistical variations. By performing computations on a small subset of the generated data, we train an ensemble of four supervised learning algorithms and use it to make predictions on the velocity of each sperm. Our results suggest that magnetophoresis can magnify the difference between normal and abnormal cells, such that a sorted sample has over twice the proportion of desirable cells. In addition, we demonstrated that the predictions from machine learning gave comparable results with significantly lower computational costs.

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Magnetophoresis of diamagnetic microparticles in a weak magnetic field

Cited by 35 publications

References 58 publications

Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet

Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet

Biocompatible and label-free separation of cancer cells from cell culture lines from white blood cells in ferrofluids

Supervised Learning to Predict Sperm Sorting by Magnetophoresis

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