High-throughput particle focusing and separation in split-recombination channel

Abstract Inertial microfluidic has been widely applied to manipulate particles or bio-sample based on the inertial lift force and Dean Vortices. This technology provides significant advantages over conventional technologies, including simple structure, high throughput and freedom from an external field. Among many inertial microfluidic systems, the straight microchannel is commonly used to produce inertial focusing, which is a phenomenon that particles or cells are aligned and separated based on their size under the influence of inertial lift force. Besides the inertial lift force, flow drag forces induced by the geometrical structures of microchannel can also affect particle focusing. Herein, a split-recombination microchannel, consisting of curved and straight channels, is proposed to focus and separate particles at high flow rate. As compared with the straight channel, the particle focusing in the split-recombination channel is greatly improved, which results from the combined effects of the inertial lift force, the curvature-induced Dean drag force and the structure of split and recombination. Moreover, the distribution of different-sized particles in designed microchannel is investigated. The results indicate that the proposed microchannel not only enhances the particle focusing but also enables the separation of different-sized particles with high throughput. Finally, it is discovered that the larger length of straight channel and curvature radius of curved channel can result in a more efficient particle separation. Another important feature of designed split-recombination microchannel is that it can be arranged in parallel to handle large-volume samples, holding great potential in lab-on-a-chip applications.

Download Full-text

A Microchannel With Repeated Sharp Corners for Single Stream Particle Focusing

ASME 2014 12th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2014-21578 ◽

2014 ◽

Author(s):

Liangliang Fan ◽

Xukun He ◽

Liang Zhao ◽

Yu Han ◽

Jiang Zhe

Keyword(s):

Centrifugal Force ◽

High Throughput ◽

Flow Rate ◽

Lift Force ◽

Channel Wall ◽

Sharp Corner ◽

Force Effect ◽

Particle Focusing ◽

Wide Range ◽

Sharp Corners

A new microfluidic device for fast and high throughput microparticle focusing is reported. The particle focusing is based on the combination of inertial lift force effect and centrifugal force effect generated in a microchannel with a series of repeated sharp corners on one side of the channel wall. The inertial lift force effect induces two focused particles streams in the microchannel, and the centrifugal force generated at the sharp corner structures tends to drive the particles laterally away from the corner. With the use of a series of the repeated, sharp corner structures, a single and highly focused particle stream was achieved near the straight channel wall at a wide range of flow rates. In comparison to other hydrodynamic particle focusing methods, this method is less sensitive to the flow rate and can work at a higher flow rate (high throughput). With its simple structure and operation, and high throughput, this method can be potentially used in microparticle focusing processes in a variety of lab-on-a chip applications.

Download Full-text

Pattern Transition on Inertial Focusing of Neutrally Buoyant Particles Suspended in Rectangular Duct Flows

Micromachines ◽

10.3390/mi12101242 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1242

Author(s):

Hiroshi Yamashita ◽

Takeshi Akinaga ◽

Masako Sugihara-Seki

Keyword(s):

Cross Section ◽

Lift Force ◽

Pitchfork Bifurcation ◽

Blockage Ratio ◽

Duct Flow ◽

Rectangular Duct ◽

Inertial Focusing ◽

Particle Focusing ◽

Wide Range ◽

The Cross

The continuous separation and filtration of particles immersed in fluid flows are important interests in various applications. Although the inertial focusing of particles suspended in a duct flow is promising in microfluidics, predicting the focusing positions depending on the parameters, such as the shape of the duct cross-section and the Reynolds number (Re) has not been achieved owing to the diversity of the inertial-focusing phenomena. In this study, we aimed to elucidate the variation of the inertial focusing depending on Re in rectangular duct flows. We performed a numerical simulation of the lift force exerted on a spherical particle flowing in a rectangular duct and determined the lift-force map within the duct cross-section over a wide range of Re. We estimated the particle trajectories based on the lift map and Stokes drag, and identified the particle-focusing points appeared in the cross-section. For an aspect ratio of the duct cross-section of 2, we found that the blockage ratio changes transition structure of particle focusing. For blockage ratios smaller than 0.3, particles focus near the centres of the long sides of the cross-section at low Re and near the centres of both the long and short sides at relatively higher Re. This transition is expressed as a subcritical pitchfork bifurcation. For blockage ratio larger than 0.3, another focusing pattern appears between these two focusing regimes, where particles are focused on the centres of the long sides and at intermediate positions near the corners. Thus, there are three regimes; the transition between adjacent regimes at lower Re is found to be expressed as a saddle-node bifurcation and the other transition as a supercritical pitchfork bifurcation.

Download Full-text

Inertial focusing and zeta potential measurements of single-nanoparticles using octet-nanochannels

Lab on a Chip ◽

10.1039/d1lc00239b ◽

2021 ◽

Author(s):

Shohei Kishimoto ◽

Makusu Tsutsui ◽

Kazumichi Yokota ◽

Masateru Taniguchi

Keyword(s):

Zeta Potential ◽

Inertial Effects ◽

Inertial Focusing ◽

Particle Focusing ◽

Single Nanoparticle

Electrokinetics in octet nanochannels was demonstrated to enable particle focusing via inertial effects to accurate single-nanoparticle zeta-potential measurements.

Download Full-text

Inertial focusing of finite-size particles in microchannels

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.95 ◽

2018 ◽

Vol 840 ◽

pp. 613-630 ◽

Cited By ~ 23

Author(s):

Evgeny S. Asmolov ◽

Alexander L. Dubov ◽

Tatiana V. Nizkaya ◽

Jens Harting ◽

Olga I. Vinogradova

Keyword(s):

Lattice Boltzmann ◽

Slip Velocity ◽

Lift Force ◽

Finite Size ◽

Reynolds Numbers ◽

Velocity Difference ◽

Inertial Focusing ◽

Inertial Migration ◽

Lattice Boltzmann Simulations ◽

Insight Into

At finite Reynolds numbers, $Re$, particles migrate across laminar flow streamlines to their equilibrium positions in microchannels. This migration is attributed to a lift force, and the balance between this lift and gravity determines the location of particles in channels. Here we demonstrate that velocity of finite-size particles located near a channel wall differs significantly from that of an undisturbed flow, and that their equilibrium position depends on this, referred to as slip velocity, difference. We then present theoretical arguments, which allow us to generalize expressions for a lift force, originally suggested for some limiting cases and $Re\ll 1$, to finite-size particles in a channel flow at $Re\leqslant 20$. Our theoretical model, validated by lattice Boltzmann simulations, provides considerable insight into inertial migration of finite-size particles in a microchannel and suggests some novel microfluidic approaches to separate them by size or density at a moderate $Re$.

Download Full-text

Inertial focusing in a parallelogram profiled microchannel over a range of aspect ratios

Micro and Nano Systems Letters ◽

10.1186/s40486-019-0102-9 ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

Joo Young Kwon ◽

Dong-Ki Lee ◽

Jungwoo Kim ◽

Young Hak Cho

Keyword(s):

Aspect Ratio ◽

Cfd Simulation ◽

Rectangular Cross Section ◽

Wet Etching ◽

Pdms Mold ◽

Rectangular Microchannel ◽

Inertial Focusing ◽

Particle Focusing ◽

Aspect Ratios ◽

Si Wafer

AbstractIn this study, particle focusing phenomena are studied in parallelogram and rectangular cross-sectioned microchannels of varying aspect ratio. In contrast to prior work the microchannels were fabricated using anisotropic wet etching of a Si wafer, plasma bonding, and self-alignment between the Si channel and the PDMS mold. It is shown that the inertial focusing points of the fabricated microchannels of parallelogram and rectangular cross-section were modified as the aspect ratio of the microchannels changed. The particle focusing points of the parallelogram profiled microchannel are compared with those of the rectangular microchannel through experimental measurements and CFD simulation. It is shown that particles can be efficiently focused and separated at a relatively low Reynolds number using a parallelogram profiled microchannel with a low aspect ratio.

Download Full-text

Sheathless Dean-flow-coupled elasto-inertial particle focusing and separation in viscoelastic fluid

RSC Advances ◽

10.1039/c6ra25328h ◽

2017 ◽

Vol 7 (6) ◽

pp. 3461-3469 ◽

Cited By ~ 16

Author(s):

Dan Yuan ◽

Say Hwa Tan ◽

Qianbin Zhao ◽

Sheng Yan ◽

Ronald Sluyter ◽

...

Keyword(s):

Viscoelastic Fluid ◽

Straight Channel ◽

Inertial Particle ◽

Channel Section ◽

Dean Flow ◽

Particle Focusing

Sheathless particle focusing and separation in viscoelastic fluid is demonstrated using an integrated ECCA (straight channel section with asymmetrical expansion–contraction cavity arrays) straight channel.

Download Full-text

High-Throughput Particle Concentration Using Complex Cross-Section Microchannels

Micromachines ◽

10.3390/mi11040440 ◽

2020 ◽

Vol 11 (4) ◽

pp. 440 ◽

Cited By ~ 1

Author(s):

Asma Mihandoust ◽

Sajad Razavi Bazaz ◽

Nahid Maleki-Jirsaraei ◽

Majid Alizadeh ◽

Robert A. Taylor ◽

...

Keyword(s):

Cross Section ◽

High Throughput ◽

Cross Sections ◽

Particle Concentration ◽

Separation Efficiency ◽

Channel Cross Section ◽

Total Width ◽

Particle Focusing ◽

Complex Cross ◽

Complex Cross Section

High throughput particle/cell concentration is crucial for a wide variety of biomedical, clinical, and environmental applications. In this work, we have proposed a passive spiral microfluidic concentrator with a complex cross-sectional shape, i.e., a combination of rectangle and trapezoid, for high separation efficiency and a confinement ratio less than 0.07. Particle focusing in our microfluidic system was observed in a single, tight focusing line, in which higher particle concentration is possible, as compared with simple rectangular or trapezoidal cross-sections with similar flow area. The sharper focusing stems from the confinement of Dean vortices in the trapezoidal region of the complex cross-section. To quantify this effect, we introduce a new parameter, complex focusing number or CFN, which is indicative of the enhancement of inertial focusing of particles in these channels. Three spiral microchannels with various widths of 400 µm, 500 µm, and 600 µm, with the corresponding CFNs of 4.3, 4.5, and 6, respectively, were used. The device with the total width of 600 µm was shown to have a separation efficiency of ~98%, and by recirculating, the output concentration of the sample was 500 times higher than the initial input. Finally, the investigation of results showed that the magnitude of CFN relies entirely on the microchannel geometry, and it is independent of the overall width of the channel cross-section. We envision that this concept of particle focusing through complex cross-sections will prove useful in paving the way towards more efficient inertial microfluidic devices.

Download Full-text