Particle focusing in microfluidic devices

Xuan, Xiangchun; Zhu, Junjie; Church, Christopher

doi:10.1007/s10404-010-0602-7

Cited by 324 publications

(282 citation statements)

References 140 publications

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“…1. The results demonstrated in this study will be practically important in the design of microflow cytometer, a miniaturized device used to count or sort cells [11][12][13] . The ability to focus particles in a spatially narrow stream is a prerequisite in such equipment to accurately manipulate the cells 11 .…”

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confidence: 87%

“…The results demonstrated in this study will be practically important in the design of microflow cytometer, a miniaturized device used to count or sort cells [11][12][13] . The ability to focus particles in a spatially narrow stream is a prerequisite in such equipment to accurately manipulate the cells 11 . However, the methods currently in use-active focusing by electric or acoustic forces and passive focusing such as inertial focusing-demand complicated structures, as they require generating external fields or secondary flows, and further their throughputs are restricted by a narrow range of flow rates 11 .…”

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confidence: 87%

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DNA-based highly tunable particle focuser

et al. 2013

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DNA is distinguished by both long length and structural rigidity. Classical polymer theories predict that DNA enhances the non-Newtonian elastic properties of its dilute solution more significantly than common synthetic flexible polymers because of its larger size and longer relaxation time. Here we exploit this property to report that under Poiseuille microflow, rigid spherical particles laterally migrate and form a tightly focused stream in an extremely dilute DNA solution (0.0005 (w/v)%). By the use of the DNA solution, we achieve highly efficient focusing (499.5%) over an unprecedented wide range of flow rates (ratio of maximum to minimum flow rates B400). This highly tunable particle-focusing technique can be used in the design of cost-effective portable flow cytometers, high-throughput cell analysis and also for cell sorting by size. We demonstrate that DNA is an efficient elasticity enhancer, which originates from its unique structural properties.

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confidence: 87%

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confidence: 87%

DNA-based highly tunable particle focuser

et al. 2013

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“…[4][5][6] Microfluidic systems have been proven to be promising tools for particle/cell manipulation with higher sensitivity and accuracy than their macroscale counterparts. The last decade has seen extensive development of microfluidic approaches for particle/cell manipulation that resort to immunocapture, 7 externally applied physical fields, [8][9][10][11][12][13][14][15][16][17][18] microfiltration, 19,20 gravitational sedimentation, 21 or deterministic lateral migration.…”

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confidence: 99%

Size-Based Separation of Particles and Cells Utilizing Viscoelastic Effects in Straight Microchannels

et al. 2015

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Viscoelasticity-induced particle migration has recently received increasing attention due to its ability to obtain high-quality focusing over a wide range of flow rates. However, its application is limited to low throughput regime since the particles can defocus as flow rate increases. Using an engineered carrier medium with constant and low viscosity and strong elasticity, the sample flow rates are improved to be one order of magnitude higher than those in existing studies. Utilizing differential focusing of particles of different sizes, here we present sheathless particle/cell separation in simple straight microchannels that possess excellent parallelizability for further throughput enhancement. The present method can be implemented over a wide range of particle/cell sizes and flow rates. We successfully separate small particles from larger particles, MCF-7 cells from red blood cells (RBCs), and Escherichia coli (E. coli) bacteria from RBCs in different straight microchannels. The proposed method could broaden the applications of viscoelastic microfluidic devices to particle/cell separation due to the enhanced sample throughput and simple channel design.Continuous manipulation and separation of particles and cells is important for a wide range of applications in biology, 1,2 medicine, 2,3 and industry. [4][5][6] Microfluidic systems have been proven to be promising tools for particle/cell manipulation with higher sensitivity and accuracy than their macroscale counterparts. The last decade has seen extensive development of microfluidic approaches for particle/cell manipulation that resort to immunocapture, 7 externally applied physical fields, [8][9][10][11][12][13][14][15][16][17][18] microfiltration, 19,20 gravitational sedimentation, 21 or deterministic lateral migration. 22,23 More recently, cross-streamline migration induced by the hydrodynamic effects of carrier media, such as inertia 24,25 and viscoelasticity, 26,27 has shown its promise for effective particle/cell manipulation without need of labeling and external force fields. Particles and cells can be separated based on the size-dependent nature of hydrodynamic forces. Briefly, the inertial lift scales as F a ∝ , where a is the particle diameter. There are several cell types of biological and clinical interest with separable size ranges: epithelial tumor cells (15-25 µm in diameter), blood cells (erythrocytes are 6-8 µm biconcave disks and peripheral blood lymphocytes are 7-10 µm in diameter), and bacteria (1-3 µm). Inertial migration in Newtonian fluids has been intensively studied and implemented in high-throughput label-free separation devices for cell separation. [28][29][30][31][32][33][34] Recently, particle migration induced by viscoelasticity has begun to attract increasing attention due to its simple focusing pattern and potential for achieving efficient focusing over a wide range of flow rates. 35,36 In a viscoelastic medium, elasticity coupled with non-negligible inertia will drive particles towards the channel centerline, whic...

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“…To be truly competitive with standard instrumentation, these microfluidic devices should satisfy several challenging constraints: (i) a high throughput, necessary to process large amounts of samples in a reasonable amount of time; (ii) a low pressure drop over the microfluidic device, which basically means low fluidic resistance, thus allowing vacuum driven flows; (iii) optical accessibility inside the microchannel to allow high quality optical detection 3 . Moreover, a fundamental requirement is the capability to perform 3D particle focusing that forces the cells to flow one behind the other to enable enhanced optical alignment with better signal 4,5 . Unfortunately, due to the intrinsic 2D nature of the standard fabrication techniques, this achievement is difficult to obtain.…”

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confidence: 99%

Particle focusing by 3D inertial microfluidics

et al. 2017

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Three-dimensional (3D) particle focusing in microfluidics is a fundamental capability with a wide range of applications, such as on-chip flow cytometry, where high-throughput analysis at the single-cell level is performed. Currently, 3D focusing is achieved mainly in devices with complex layouts, additional sheath fluids, and complex pumping systems. In this work, we present a compact microfluidic device capable of 3D particle focusing at high flow rates and with a small footprint, without the requirement of external fields or lateral sheath flows, but using only a single-inlet, single-outlet microfluidic sequence of straight channels and tightly curving vertical loops. This device exploits inertial fluidic effects that occur in a laminar regime at sufficiently high flow rates, manipulating the particle positions by the combination of inertial lift forces and Dean drag forces. The device is fabricated by femtosecond laser irradiation followed by chemical etching, which is a simple two-step process enabling the creation of 3D microfluidic networks in fused silica glass substrates. The use of tightly curving three-dimensional microfluidic loops produces strong Dean drag forces along the whole loop but also induces an asymmetric Dean flow decay in the subsequent straight channel, thus producing rapid cross-sectional mixing flows that assist with 3D particle focusing. The use of out-of-plane loops favors a compact parallelization of multiple focusing channels, allowing one to process large amounts of samples. In addition, the low fluidic resistance of the channel network is compatible with vacuum driven flows. The resulting device is quite interesting for high-throughput on-chip flow cytometry.

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Particle focusing in microfluidic devices

Cited by 324 publications

References 140 publications

DNA-based highly tunable particle focuser

DNA-based highly tunable particle focuser

Size-Based Separation of Particles and Cells Utilizing Viscoelastic Effects in Straight Microchannels

Particle focusing by 3D inertial microfluidics

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