Multi-Stage Particle Separation based on Microstructure Filtration and Dielectrophoresis

Yin, Danfen; Zhang, Xiaoling; Han, Xianwei; Yang, Jun; Hu, Ning

doi:10.3390/mi10020103

Cited by 19 publications

(12 citation statements)

References 53 publications

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“…An ultrasonic method achieved a low separation efficiency, although the samples were separated under a high flow rate [13]. Unlike passive methods [17][18][19], no clogging effect was observed [20][21][22] when beads were trapped and accumulated, because there was no passive structure. The proposed method can be used in water pre-treatment for the extraction and concentration of suspended biological particles, as the operation method was not influenced by the physical particle properties.…”

Section: Discussionmentioning

confidence: 99%

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Fabrication of a Pneumatic Microparticle Concentrator

Jang

Jeong

2019

Micromachines

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We developed a microfluidic platform employing (normally open) pneumatic valves for particle concentration. The device features a three-dimensional network with a curved fluidic channel and three pneumatic valves (a sieve valve (Vs) that concentrates particles and two ON/OFF rubber-seal pneumatic valves that block the working fluid). Double-sided replication employing polydimethylsiloxane (PDMS) was used to fabricate the network, channel, and chamber. Particles were blocked by deformation of the Vs diaphragm, and then accumulated in the curved microfluidic channel. The working fluid was discharged via operation of the two ON/OFF valves. After concentration, particles were released to an outlet port. The Vs pressure required to block solid particles varying in diameter was determined based on the height of the curved microchannel and a finite element method (FEM) simulation of Vs diaphragm displacement. Our method was verified according to the temporal response of the fluid flow rate controlled by the pneumatic valves. Furthermore, all particles with various diameters were successfully blocked, accumulated, and released. The operating pressure, time required for concentration, and concentration ratio were dependent on the particle diameter. The estimated concentration percentage of 24.9 µm diameter polystyrene particles was about 3.82% for 20 min of operation.Micromachines 2020, 11, 40 2 of 12 are lifted, and then the trapped cells are released. A microfiltration mechanism of particles using structural deformation of the thin membrane was developed [25]. The beads or cells are trapped at voids formed in the two corners of a microfluidic channel by the structural difference between the pneumatically inflated thin diaphragm and the microfluidic channel with a rectangular cross section. A pneumatic filtration system was also developed for the size-based separation of particles [26]. It consists of the pneumatic micropump for automatic liquid transport and normally closed valves for the separation of the particles. The filtration mechanism is based on adjustable deformation of the flexible membrane, defining the gap between the microchannel and the floating block structure, which determines the maximum diameter of the bead/cell that can pass through the filter structure. An integrated microfluidic device for dynamic trapping and high-throughput patterning of cells using pneumatic microstructures [27] was investigated. There are two kinds of membrane structures, that is, an array of active U-shaped microstructures for dynamic localization of cells and an umbrella structure for protecting trapped cells in the process of rinsing.In general, these methods are suitable for handling a limited number of particles when considering the operating methods and structures of the microfluidic platform. The operation conditions such as the flow rate and the magnitude of the compressed air pressure are carefully controlled to prevent unwanted damage to the cells. Further, additional microstructures are also needed to increase cell tr...

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Section: Discussionmentioning

confidence: 99%

“…As the external forces imparted to target particles in microfluidic systems are generally weak, the flow rate must be carefully controlled. Typically, passive microfluidic devices feature micropillars in the microchannels [17][18][19]. Particles are trapped via physical interaction with the streaming working fluid.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of a Pneumatic Microparticle Concentrator

Jang

Jeong

2019

Micromachines

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“…If the electric field is non-uniform, the electric-field strengths on the two sides of the particle differ, and the size of the induced dipole is not equal. The resultant force, which is called the dielectrophoretic force, is nonzero, resulting in particle movement [ 30 ]. The time-averaged dielectrophoretic force of a spherical particle in a non-uniform electric field can be expressed as follows:

where

represents the dielectrophoretic force to which the particles are subjected,

represents the absolute permittivity of the suspending medium;

represents the particle radius,

represents the gradient of the square of the electric-field intensity, and

represents the Clausius–Mossotti factor (also known as the CM factor), which is determined by the electric-field frequency and the complex permittivity of the suspending medium [ 31 ].…”

Section: Methodsmentioning

confidence: 99%

Dielectrophoretic Separation of Particles Using Microfluidic Chip with Composite Three-Dimensional Electrode

et al. 2020

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Integrating three-dimensional (3D) microelectrodes on microfluidic chips based on polydimethylsiloxane (PDMS) has been a challenge. This paper introduces a composite 3D electrode composed of Ag powder (particle size of 10 nm) and PDMS. Ethyl acetate is added as an auxiliary dispersant during the compounding process. A micromachining technique for processing 3D microelectrodes of any shape and size was developed to allow the electrodes to be firmly bonded to the PDMS chip. Through theoretical calculations, numerical simulations, and experimental verification, the role of the composite 3D microelectrodes in separating polystyrene particles of three different sizes via dielectrophoresis was systematically studied. This microfluidic device separated 20-, 10-, and 5-μm polystyrene particles nondestructively, efficiently, and accurately.

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“…This phenomenon is called positive DEP (or pDEP). On the other hand, if the microparticles are less polarizable than the medium, it will move toward the low electric field gradient in a phenomenon called negative DEP (nDEP) [31,32,33]. The mathematical expression for the DEP force acting on a microparticle is given by Equation (1) [29,34].…”

Section: Introductionmentioning

confidence: 99%

Dielectrophoresis Multipath Focusing of Microparticles through Perforated Electrodes in Microfluidic Channels

et al. 2019

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This paper presents focusing of microparticles in multiple paths within the direction of the flow using dielectrophoresis. The focusing of microparticles is realized through partially perforated electrodes within the microchannel. A continuous electrode on the top surface of the microchannel is considered, while the bottom side is made of a circular meshed perforated electrode. For the mathematical model of this microfluidic channel, inertia, buoyancy, drag and dielectrophoretic forces are brought up in the motion equation of the microparticles. The dielectrophoretic force is accounted for through a finite element discretization taking into account the perforated 3D geometry within the microchannel. An ordinary differential equation is solved to track the trajectories of the microparticles. For the case of continuous electrodes using the same mathematical model, the numerical simulation shows a very good agreement with the experiments, and this confirms the validation of focusing of microparticles within the proposed perforated electrode microchannel. Microparticles of silicon dioxide and polystyrene are used for this analysis. Their initial positions and radius, the Reynolds number, and the radius of the pore in perforated electrodes mainly conduct microparticles trajectories. Moreover, the radius of the pore of perforated electrode is the dominant factor in the steady state levitation height.

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Multi-Stage Particle Separation based on Microstructure Filtration and Dielectrophoresis

Cited by 19 publications

References 53 publications

Fabrication of a Pneumatic Microparticle Concentrator

Fabrication of a Pneumatic Microparticle Concentrator

Dielectrophoretic Separation of Particles Using Microfluidic Chip with Composite Three-Dimensional Electrode

Dielectrophoresis Multipath Focusing of Microparticles through Perforated Electrodes in Microfluidic Channels

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