Method For Separation Of Particles Research Articles

Characteristics of electrical field flow fractionation with chronoamperometry and electrochemical impedance

Electrical field flow fractionation (EFFF) is a particle separation method that employs an electrical field to cause particles in the carrier flow transferring in the vertical direction. The electrical characteristics of EFFF are one of the important aspects to explore electrical field how to work on the particle separation in EFFF channel. The equivalent electrical circuit model of EFFF channel was built. The experiments of chronoamperometry and electrochemical impedance spectroscopy (EIS) were conducted on the EFFF channel. The electrical circuit was utilised to fit the data of EIS experiments on EFFF channel. The fitting data were compared with the experimental data of EIS. The result indicates that the experimental data is highly quantified with the fitting data. It manifested that the equivalent electrical circuit reflected the electrical characteristics of the EFFF channel.

Evaluation of acoustic-based particle separation methods

Purpose This paper aims to Separation and sorting of biological cells is desirable in many applications for analyzing cell properties, such as disease diagnostics, drugs delivery, chemical processing and therapeutics. Design/methodology/approach Acoustic energy-based bioparticle separation is a simple, viable, bio-compatible and contact-less technique using, which can separate the bioparticles based on their density and size, with-out labeling the sample particles. Findings Conventionally available bioparticle separation techniques as fluorescence and immunomagnetic may cause a serious threat to the life of the cells due to various compatibility issues. Moreover, they also require an extra pre-processing labeling step. Contrarily, label-free separation can be considered as an alternative solution to the traditional bio-particle separation methods, due to their simpler operating principles and lower cost constraints. Acoustic based particle separation methods have captured a lot of attention among the other reported label-free particle separation techniques because of the numerous advantages it offers. Practical implications This study tries to briefly cover the developments of different acoustic-based particle separation techniques over the years. Unlike the conventional surveys on general bioparticles separation, this study is focused particularly on the acoustic-based particle separation. The study would provide a comprehensive guide for the future researchers especially working in the field of the acoustics, in studying and designing the acoustic-based particle separation techniques. Originality/value The study insights a brief theory of different types of acoustic waves and their interaction with the bioparticles is considered, followed by acoustic-based particle separation devices reported till the date. The integration of acoustic-based separation techniques with other methods and with each other is also discussed. Finally, all major aspects like the approach, and productivity, etc., of the adopted acoustic particle separation methods are sketched in this article.

Efficient paradigm to enhance particle separation in deterministic lateral displacement arrays

Microfluidics based particle sorting and separation methods are gaining momentum to be applied for various applications. Deterministic lateral displacement (DLD) methods are prominent for high resolution in separation and there has been extensive studies to develop more efficient devices based on the DLD. However, it is still challenging to fully eliminate negative effects of the boundaries that degrade particle separation efficiency by perturbing the fluid flow in the channel. In this article, we present two equations to optimize channels’ geometry near the boundaries. Implementing the equations, the fluid behavior is improved around the pillars and thereby, separation efficiency is increased. The Boundary Correction Paradigm (BCP) enhances the microchannel’s functionality as much as 2–3 times and can be highly beneficial in microchannels. Also, an equation is proposed in order to recalibrate the BCP in microchannels with desired pillar diameters. The calibration equation assures high accuracy and resolution of the DLD devices corrected with the BCP.

Separation of particles with bacterial size range using the control of sheath flow ratio in spiral microfluidic channel

A method of concentrating and separating small particles with a specific size in a microfluidic system can be applied to obtain high-purity biological samples, such as viruses, bacteria, and cells. This paper presents the highly efficient separation method of bacteria-sized particles using Dean flow and inertial force in a curved spiral microfluidic channel. By adjusting the flow rate ratio of particle solution to sheath flow at the inlet, the stream line of small particles circulating in the transverse direction with Dean flow becomes more distinct from large particle stream line focused at specific equilibrium position by inertial force. Therefore, submicron-sized particles can be separated from larger particles with high efficiency. In addition, the effects of the number of small particle circulations with Dean flow on the extraction efficiency have been studied. The fluidic channel has been tested for the separation of fluorescent particles with diameters of 0.81 μm, 2.29 μm, and 4.70 μm. The channel design and flow control were optimized so that 0.81-μm particles circulated in the channel along with Dean flow, while 2.29-μm and 4.70-μm particles were concentrated at separate equilibrium points by the inertial force. The extraction yields of 0.81-μm, 2.29-μm, and 4.70-μm particles were measured to be 98.42%, 97.69%, and 99.17%, respectively. Moreover, separation of bacteria from 2.29-μm and 4.70-μm particles has been demonstrated with 98.01% extraction yield.

Induced charge electro-osmotic particle separation.

Vortex-based separation is a promising method in particle-particle separation and has only been demonstrated theoretically some years ago. To date, a continuous-flow separation device based on vortices has not been conceived because many known vortices were either unstable or controlling them lacked precision. Electro-convection from induced charge electro-osmosis (ICEO) has advantages, such as adjustable flow profiles, long-range actuation, and long-lived vortices, and offers an alternative means of particle separation. We found though a different ICEO focusing behaviour of particles whereby particles were trapped and concentrated in two vortex cores. Encouraged by these features of ICEO vortices, we proposed a direct method for particle separation in continuous flow. In various experiments, we first characterized the ICEO-induced focusing performances of various kinds of particle samples in a straight channel embedded with an individual central bipolar electrode, presenting a justifiable explanation. Second, the combined dependences of ICEO particle separation on the sample size and mass density were investigated. Third, an application to cell purification was performed in which we obtained a purity surpassing 98%. Finally, we investigated the ICEO characteristics of nanoparticles, exploiting our method in isolating nanoscale objects by separating 500 nm and 5 μm polystyrene beads, gaining clear separation. Certain features of this method, such as having ease of operation, simple structure, and continuous flow, and being prefocusing free and physical property-based, indicate its good potential in tackling environmental monitoring, cell sorting, chemical analysis, isolation of uniform-sized graphene and transesterification of micro-algal lipids to biodiesel.

Shape-based separation of micro-/nanoparticles in liquid phases.

The production of particles with shape-specific properties is reliant upon the separation of micro-/nanoparticles of particular shapes from particle mixtures of similar volumes. However, compared to a large number of size-based particle separation methods, shape-based separation methods have not been adequately explored. We review various up-to-date approaches to shape-based separation of rigid micro-/nanoparticles in liquid phases including size exclusion chromatography, field flow fractionation, deterministic lateral displacement, inertial focusing, electrophoresis, magnetophoresis, self-assembly precipitation, and centrifugation. We discuss separation mechanisms by classifying them as either changes in surface interactions or extensions of size-based separation. The latter includes geometric restrictions and shape-dependent transport properties.

Using magnets for particle extraction from powder flow

A model is explored for the extraction of ferromagnetic metallic particles using a magnetic filtration system. These metallic particles, which are transported by a powder flow may be fragments resulting from the standard wear and tear on industrial machinery. A project of this nature was brought to the 2015 Mathematics and Statistics in Industry NZ Study Group. Possible configurations of the magnetic filtration systems are considered with the target of better particle capture. The dependence of the model on the metallic particle's release zone and velocity is investigated. Monte-Carlo simulations are conducted for cases using perpendicular as well as parallel magnetic rods. The results confirm the efficacy of parallel offset rods and emphasise the importance of dense rod placement. The approach could be used to explore further alternative rod arrangements in advance of experimental implementation. References S.M. Blinder (2011) Magnetic Field of a Cylindrical Bar Magnet Wolfram Demonstrations Project. http://demonstrations.wolfram.com/MagneticFieldOfACylindricalBarMagnet/ J.C. Butcher (2008) Numerical Methods for Ordinary Differential Equations , John Wiley and Sons Ltd., England. H. Cooper, J. Denier, A. Ali, V. Chopovda, A. Gulley (2017) Modelling the effectiveness of magnets in particle extraction , ANZIAM Journal (2017), 57: M332–M352. doi:10.21914/anziamj.v57i0.12037 A. Einstein (1906) Eine neue Bestimmung der Molekuldimensionen , Ann. Phys., 324: 289–306. A. Einstein, R. Furth (1893-1956) Investigations on the theory of the Brownian movement , Dover. isbn=978-0-486-60304-9 Y. Nakai, F. Mishima, Y. Akiyama, S. Nishijima (2010) Development of Magnetic Separation System for Powder Separation , IEEE Transactions on applied superconductivity, 20:3, 941-944. doi:10.1109/TASC.2010.2043086 S. Noguchi, S. Kim (2011) Development of a numerical simulation method for the magnetic separation of magnetic particles , IEEE Transactions on magnetics, 47:5, 898-901. doi:10.1109/CEFC.2010.5481745 A.W. Strandling (1993) The physics of open-gradient dry magnetic separation , International Journal of Mineral Processing, 39, 1-18. doi:10.1016/0301-7516(93)90048-F J. Svoboda, T. Fujita (2003) Recent developments in magnetic methods of material separation , Minerals Engineering, 16, 785-792. doi:10.1016/S0892-6875(03)00212-7

Controlled Fluidization, Mobility, and Clogging in Obstacle Arrays Using Periodic Perturbations.

We show that the clogging susceptibility and flow of particles moving through a random obstacle array can be controlled with a transverse or longitudinal ac drive. The flow rate can vary over several orders of magnitude, and we find both an optimal frequency and an optimal amplitude of driving that maximizes the flow. For dense arrays, at low ac frequencies, a heterogeneous creeping clogged phase appears in which rearrangements between different clogged configurations occur. At intermediate frequencies, a high-mobility fluidized state forms, and, at high frequencies, the system reenters a heterogeneous frozen clogged state. These results provide a technique for optimizing flow through heterogeneous media that could also serve as the basis for a particle separation method.

Particle Shape Influences Settling and Sorting Behavior in Microfluidic Domains

We present a new numerical model to simulate settling trajectories of discretized individual or a mixture of particles of different geometrical shapes in a quiescent fluid and their flow trajectories in a flowing fluid. Simulations unveiled diverse particle settling trajectories as a function of their geometrical shape and density. The effects of the surface concavity of a boomerang particle and aspect ratio of a rectangular particle on the periodicity and amplitude of oscillations in their settling trajectories were numerically captured. Use of surrogate circular particles for settling or flowing of a mixture of non-circular particles were shown to miscalculate particle velocities by a factor of 0.9–2.2 and inaccurately determine the particles’ trajectories. In a microfluidic chamber with particles of different shapes and sizes, simulations showed that steady vortices do not necessarily always control particle entrapments, nor do larger particles get selectively and consistently entrapped in steady vortices. Strikingly, a change in the shape of large particles from circular to elliptical resulted in stronger entrapments of smaller circular particles, but enhanced outflows of larger particles, which could be an alternative microfluidics-based method for sorting and separation of particles of different sizes and shapes.

A Study of the Particle-Level Fabric and Morphology of Granular Soils under One-Dimensional Compression Using Insitu X-ray CT Imaging.

The particle morphology and fabric of a granular soil influence its mechanical behavior. This study focuses on the evolution of the particle-level fabric and morphology of a uniformly graded sand sample subjected to one-dimensional compression up to 64 MPa. The microstructural changes with increased stresses were captured using in situ high-resolution X-ray computed tomography (X-ray CT) imaging. The processed images of particles were separated using the Monash Particle Separation Method (MPSM) for subsequent fabric and morphological analyses. The variations of various fabric parameters were studied using the separated particle volumes. New methods of assessing the morphology and crushability of particles were introduced including a comprehensive algorithm for determining coordination number, branch and contact normal vectors. Results of all fabric parameters were analyzed and discussed with reference to observed changes. Potential mechanisms were identified and relevant correlations were developed where warranted.

A multilayer lateral-flow microfluidic device for particle separation

Particle separation technology plays an important role in a wide range of applications as a critical sample preprocessing step for analysis. In this work, we proposed and fabricated a multilayer lateral-flow particle filtration and separation device based on polydimethylsiloxane molding and transfer bonding techniques. Particle separation capability was demonstrated by 4.5-um polystyrene bead filtration and cancer cell (SK-BR-3) retrieving. This device exhibits higher throughput compared with most active particle separation methods and is less vulnerable to membrane clogging problem. This novel multilayer particle filtration and separation device is expected to find applications in biomedical, environmental and microanalysis fields.

Numerical Investigation into Particle Separation Methods Using Inertial Focusing Behavior

Numerical Investigation into Particle Separation Methods Using Inertial Focusing Behavior

A New Cluster Analysis-Marker-Controlled Watershed Method for Separating Particles of Granular Soils.

An accurate determination of particle-level fabric of granular soils from tomography data requires a maximum correct separation of particles. The popular marker-controlled watershed separation method is widely used to separate particles. However, the watershed method alone is not capable of producing the maximum separation of particles when subjected to boundary stresses leading to crushing of particles. In this paper, a new separation method, named as Monash Particle Separation Method (MPSM), has been introduced. The new method automatically determines the optimal contrast coefficient based on cluster evaluation framework to produce the maximum accurate separation outcomes. Finally, the particles which could not be separated by the optimal contrast coefficient were separated by integrating cuboid markers generated from the clustering by Gaussian mixture models into the routine watershed method. The MPSM was validated on a uniformly graded sand volume subjected to one-dimensional compression loading up to 32 MPa. It was demonstrated that the MPSM is capable of producing the best possible separation of particles required for the fabric analysis.

Rapid prototyping and parametric optimization of plastic acoustofluidic devices for blood-bacteria separation.

Acoustic manipulation has emerged as a versatile method for microfluidic separation and concentration of particles and cells. Most recent demonstrations of the technology use piezoelectric actuators to excite resonant modes in silicon or glass microchannels. Here, we focus on acoustic manipulation in disposable, plastic microchannels in order to enable a low-cost processing tool for point-of-care diagnostics. Unfortunately, the performance of resonant acoustofluidic devices in plastic is hampered by a lack of a predictive model. In this paper, we build and test a plastic blood-bacteria separation device informed by a design of experiments approach, parametric rapid prototyping, and screening by image-processing. We demonstrate that the new device geometry can separate bacteria from blood while operating at 275% greater flow rate as well as reduce the power requirement by 82%, while maintaining equivalent separation performance and resolution when compared to the previously published plastic acoustofluidic separation device.

Flow rate-insensitive microparticle separation and filtration using a microchannel with arc-shaped groove arrays

Inertial microfluidics can separate microparticles in a continuous and high-throughput manner, and is very promising for a wide range of industrial, biomedical and clinical applications. However, most of the proposed inertial microfluidic devices only work effectively at a limited and narrow flow rate range because the performance of inertial particle focusing and separation is normally very sensitive to the flow rate (Reynolds number). In this work, an innovative particle separation method is proposed and developed by taking advantage of the secondary flow and particle inertial lift force in a straight channel (AR = 0.2) with arc-shaped groove arrays patterned on the channel top surface. Through the simulation results achieved, it can be found that a secondary flow is induced within the cross section of the microchannel and guides different-size particles to the corresponding equilibrium positions. On the other hand, the effects of the particle size, flow rate and particle concentration on particle focusing and separation quality were experimentally investigated. In the experiments, the performance of particle focusing, however, was found relatively insensitive to the variation of flow rate. According to this, a separation of 4.8 and 13 µm particle suspensions was designed and successfully achieved in the proposed microchannel, and the results show that a qualified particle separation can be achieved at a wide range of flow rate. This flow rate-insensitive microfluidic separation (filtration) method is able to potentially serve as a reliable biosample preparation processing step for downstream bioassays.

Asymmetrical Deterministic Lateral Displacement Gaps for Dual Functions of Enhanced Separation and Throughput of Red Blood Cells

Deterministic lateral displacement (DLD) method for particle separation in microfluidic devices has been extensively used for particle separation in recent years due to its high resolution and robust separation. DLD has shown versatility for a wide spectrum of applications for sorting of micro particles such as parasites, blood cells to bacteria and DNA. DLD model is designed for spherical particles and efficient separation of blood cells is challenging due to non-uniform shape and size. Moreover, separation in sub-micron regime requires the gap size of DLD systems to be reduced which exponentially increases the device resistance, resulting in greatly reduced throughput. This paper shows how simple application of asymmetrical DLD gap-size by changing the ratio of lateral-gap (GL) to downstream-gap (GD) enables efficient separation of RBCs without greatly restricting throughput. This method reduces the need for challenging fabrication of DLD pillars and provides new insight to the current DLD model. The separation shows an increase in DLD critical diameter resolution (separate smaller particles) and increase selectivity for non-spherical RBCs. The RBCs separate better as compared to standard DLD model with symmetrical gap sizes. This method can be applied to separate non-spherical bacteria or sub-micron particles to enhance throughput and DLD resolution.

Field-flow fractionation of microparticles in a rotating coiled column for the preparative separation of sorption materials

It is demonstrated that field-flow fractionation using a rotating coiled column (RCC) can be used for the separation and purification of the polydisperse sorbents based on polystyrene–divinylbenzene. The behavior of the sorbent at different operating parameters of RCC was studied. The mobile phase composition, column rotation speed, and the initial flow rate of the mobile phase were selected, optimized for the isolation of a monodisperse fraction with the particle size 4.5 µm and the separation of particles 0.5–2 µm in size, particle fragments, and residues of sorbent synthesis. It is shown that a 15-mL analytical RCC ensures the efficient fractionation of 100 mg of the sorbent in one experiment taking less than one hour with the yield of the desired fraction greater than 95%. The perspectives for scaling up the fractionation in RCC are evaluated; the possibility of using the method for the preparative separation of particles of different nature is discussed.

On the Application of Inertial Microfluidics for the Size-Based Separation of Polydisperse Cementitious Particulates

The early‐age performance of concrete is determined by the properties of the cementitious binder and the evolution of its chemical reactions. The chemical reactivity, and to some extent, the composition of cementitious particles can depend on particle size. Therefore, it is valuable to physically separate cementing minerals into well‐defined size classes so that the influences of both particle size and composition on reaction progress can be studied without the confounding effects of a broad particle size distribution. However, conventional particle separation methods (e.g., density fractionation, wet sieving, field-flow extraction, ultrasonification-sedimentation) are time-consuming and cumbersome and result in poor particle yields and size-selectivity, thus, making them unsuitable for processing larger volumes of cementitious powders (on the order of grams). This study applies a novel inertial microfluidics (IMF) based procedure to separate cementitious powders on the basis of their size. Special attention is paid to optimizing operating variables to ensure that particles in a fluid streamline achieve unique equilibrium positions within the device. From such positions, particles can be retrieved as per their size using symmetrical outlet configurations with tuned fluidic resistances. The approach is critically assessed in terms of: (1) its ability to separate cementitious powders into narrow size bins, and therefore its feasibility as a fractionation procedure, and (2) quantitatively relating the operating parameters to the particle yield and size selectivity. The study establishes metrics for assessing the ability of IMF methods to classify minerals and other polydisperse particles on the basis of their size.

Continuous Microfluidic Particle Separation via Elasto-Inertial Pinched Flow Fractionation.

Many of the fluids encountered in chemical and biomedical applications exhibit non-Newtonian behavior. However, the majority of current particle separation methods have been demonstrated in Newtonian fluids only. This work presents an experimental study of continuous particle separation in viscoelastic solutions via a combined action of elastic and inertial lift forces, which we term elasto-inertial pinched flow fractionation (eiPFF). The parametric effects on eiPFF are systematically investigated in terms of dimensionless numbers. It is found that eiPFF offers much higher particle throughput and separation resolution than the traditional steric effects-based PFF. Moreover, eiPFF works most efficiently when the Reynolds number, Re, is of order 1 and hence fills perfectly into the gap of our recently proposed inertia-enhanced PFF (iPFF) technique (Anal. Chem. 2015, 87, 4560-4565) that favors Re of the order 10 or more. However, the particle separation via eiPFF does not increase monotonically with the elasticity number at higher polymer concentrations and is strongly affected by the aspect ratio of channel width to height, both of which have not been previously reported. More surprisingly, the elasto-inertial deflection of small particles can be even greater than that of large particles in a high-aspect-ratio channel for Re less than 1.

Gravity-driven hydrodynamic particle separation in digital microfluidic systems

In the present study, the electrode configuration and actuation scheme are designed in a fashion to implement a gravity-based hydrodynamic particle separation method on digital microfluidic systems.