Focusing microparticles in a microfluidic channel with standing surface acoustic waves (SSAW)

Shi, Jinjie; Mao, Xiaole; Ahmed, Daniel; Colletti, Ashley A.; Huang, Tony Jun

doi:10.1039/b716321e

Cited by 400 publications

(342 citation statements)

References 15 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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“…The proposed design provided an additional advantage of utilizing both the horizontal and stronger vertical components of the ARF acting on the particles. The height and width of the microchannel did not significantly alter the device performance, unlike the SSAW‐based devices, in which the microchannel aspect ratio significantly affected the locations of the pressure nodes and antinodes 22, 39, 40, 42. The present device utilized a comparatively low input power because the energy loss to PDMS walls was minimal as the IDT was directly exposed to the fluid and both the vertical and horizontal components of the ARF were employed.…”

Section: Introductionmentioning

confidence: 98%

“…A SSAW is a combination of two constructively interfering TSAWs propagating in opposite directions. SSAWs form pressure nodes and antinodes inside the fluid and are used to push particles toward regions of low pressure inside the microchannel, achieving particle focusing and separation 22, 23, 24. On the other hand, TSAWs have been used in cross‐type acoustic particle separators to laterally migrate particles and realize separation across the microchannel width or within a sessile droplet, because particles predominantly migrate within the horizontal plane 11, 25, 26, 27.…”

Section: Introductionmentioning

confidence: 99%

Vertical Hydrodynamic Focusing and Continuous Acoustofluidic Separation of Particles via Upward Migration

et al. 2017

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A particle suspended in a fluid within a microfluidic channel experiences a direct acoustic radiation force (ARF) when traveling surface acoustic waves (TSAWs) couple with the fluid at the Rayleigh angle, thus producing two components of the ARF. Most SAW‐based microfluidic devices rely on the horizontal component of the ARF to migrate prefocused particles laterally across a microchannel width. Although the magnitude of the vertical component of the ARF is more than twice the magnitude of the horizontal component, it is long ignored due to polydimethylsiloxane (PDMS) microchannel fabrication limitations and difficulties in particle focusing along the vertical direction. In the present work, a single‐layered PDMS microfluidic chip is devised for hydrodynamically focusing particles in the vertical plane while explicitly taking advantage of the horizontal ARF component to slow down the selected particles and the stronger vertical ARF component to push the particles in the upward direction to realize continuous particle separation. The proposed particle separation device offers high‐throughput operation with purity >97% and recovery rate >99%. It is simple in its fabrication and versatile due to the single‐layered microchannel design, combined with vertical hydrodynamic focusing and the use of both the horizontal and vertical components of the ARF.

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“…1 With the increasing demand of more integrated functions on a chip, advancements in manufacturing technology are critical to provide flexibility in integration of heterogeneous materials, a better interface between macro and micro components, and simple routing approaches for massively parallel fluid manipulation and control. 3D microfluidics is one of the future trends since it not only significantly increases the number of functional units that can be integrated on a chip, thus increasing the processing power and throughput, but also provides many important unique functions that are difficult to realize with conventional 2D technologies, [2][3][4] such as 3D sheath flows for sample focusing 5,6 and 3D tissue engineering. [7][8][9][10][11][12][13][14] Versatile approaches have been demonstrated in the prior literature for fabricating 3D microfluidic structures.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of 3D high aspect ratio PDMS microfluidic networks with a hybrid stamp

et al. 2015

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Focusing microparticles in a microfluidic channel with standing surface acoustic waves (SSAW)

Abstract: We introduce a novel on-chip microparticle focusing technique using standing surface acoustic waves (SSAW). Our method is simple, fast, dilution-free, and applicable to virtually any type of microparticle.

Cited by 400 publications

References 15 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

Vertical Hydrodynamic Focusing and Continuous Acoustofluidic Separation of Particles via Upward Migration

Fabrication of 3D high aspect ratio PDMS microfluidic networks with a hybrid stamp

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