Dielectrophoresis Effect Research Articles

Dielectrophoresis effect on anti-icing characteristics of superhydrophobic surface

In present study, icing experiment using semiconductor refrigeration method and 3D LBM (Lattice Boltzmann method) simulation by employing improved Shan-Chen model coupling the electric field model are conducted to confirm dielectrophoresis effect on freezing characterisitic of a sessile droplet at superhydrophobic surface. Tests are performed with the same droplet diameter of d = 2.6 mm, cold wall temperature of TW = -5 °C and ambient condition (TA = 20 °C, RH = 48%). The sessile droplet freezing process is recorded at different contact angles and electric field intensities. The improved Shan-Chen model with large density ratio (ρl/ρv = 36.55), electric field model and new wettability model are applied to simulate droplet deformation. The present results show that the droplet icing time has a positive relationship with contact angle and electric field intensity, the droplet icing time is extended up to about 40 times by the couple effect of superhydrophobic coating and the electric field. The size of droplet-solid interface and electric-induced convection are the key factors of anti-icing performance.

Dielectrophoretic motion of a red blood cell in a microfluidic environment: Insights from numerical simulations

This research delves into the dielectrophoresis (DEP) behavior of a biological cell within a sinusoidal-shaped microchannel utilizing the Maxwell stress tensor (MST) theory. A red blood cell (RBC), immersed in a viscoelastic fluid, is studied considering the Oldroyd-B model. The study aims to fill a gap in the literature by examining the DEP characteristics of RBC in a realistic geometric configuration and fluid environment, bridging the divide between theoretical modeling and practical application. This work uniquely explores the DEP behavior of an RBC within a sinusoidal microchannel in the presence of a viscoelastic flow regime, which simulates plasma properties, marking a novel contribution to the field. The two-dimensional numerical model incorporates the finite element method to accurately simulate the DEP effect and describe the behavior of the viscoelastic fluid. Validation results confirm the accuracy of the MST model. Crucially, numerical findings highlight the strong dependence of DEP force on electric potential and fluid permittivity. As a consequence of their heightened levels, there is an associated increase in both the DEP force and velocity. While the augmentation of fluid viscosity merely results in a deceleration of DEP velocity. The study provides valuable insights into the interplay between physical parameters and particle behavior, paving the way for advancements in microfluidic particle manipulation techniques.

Deflection of sliding droplets by dielectrophoresis force on a superhydrophobic surface

In this study, we experimentally identify the effect of liquid dielectrophoresis (LDEP) force on a superhydrophobic surface in directing the trajectory of moving water droplets across designed interdigitated electrodes and show that this method is capable of rapidly selecting droplets at a high speed (200 mm/s). As the droplets traverse down the surface by the electric field, their deflection on the edge of these electrodes is achieved successively, allowing for the selective manipulation of discrete droplets. A series of experiments were conducted to validate the relationships among droplet deflections, applied electric fields, and dynamic contact angles. Our findings reveal that the principal driving force behind the droplet deflections is the LDEP force, which can provide instant manipulation of moving droplets rather than a variation in contact angles brought about by electrowetting. This study presents a proof-of-concept experiment utilizing LDEP for high-throughput droplet selection and also highlights the potential applications of this mechanism in high-speed digital microfluidics (DMF) and biological separation methodologies.

A Novel Hybrid Platform for Live/Dead Bacteria Accurate Sorting by On-Chip DEP Device.

According to the World Health Organization (WHO) forecasts, Antimicrobial Resistance (AMR) will be the leading cause of death worldwide in the next decades. To prevent this phenomenon, rapid Antimicrobial Susceptibility Testing (AST) techniques are required to drive the selection of the most suitable antibiotic and its dosage. In this context, we propose an on-chip platform, based on a micromixer and a microfluidic channel, combined with a pattern of engineered electrodes to exploit the di-electrophoresis (DEP) effect. The role of the micromixer is to ensure the proper interaction of the antibiotic with the bacteria over a long time (≈1 h), and the DEP-based microfluidic channel enables the efficient sorting of live from dead bacteria. A sorting efficiency of more than 98%, with low power consumption (Vpp = 1 V) and time response of 5 s, within a chip footprint of ≈86 mm2, has been calculated, which makes the proposed system very attractive and innovative for efficient and rapid monitoring of the antimicrobial susceptibility at the single-bacterium level in next-generation medicine.

Microparticle separation using dielectrophoresis-assisted inertial microfluidics: A GPU-accelerated immersed boundary-lattice Boltzmann simulation.

In this study, the migration of microparticles towards the inertial equilibrium positions in a straight microchannel with a square cross sectionin the presence of an inhomogeneous oscillating electric field was examined. The dynamics of microparticles were simulated using the immersed boundary-lattice Boltzmann method of fluid-structure interaction simulation. Moreover, the lattice Boltzmann Poisson solver was applied to calculate the electric field required for calculation of the dielectrophoretic force using the equivalent dipole moment approximation. These numerical methods were implemented on a single GPU coupled with the AA pattern of storing distribution functions in memory to speed up the computationally demanding simulation of microparticles dynamics. In the absence of an electric field, spherical polystyrene microparticles migrate to four symmetric stable equilibrium positions corresponding to the sidewalls of the square cross-sectional microchannel. The equilibrium distance from the sidewall was increased by increasing the particle size. The equilibrium positions near electrodes disappeared and particles migrated to the other equilibrium positions far from the electrodes by the application of the high-frequency oscillatory electric field at voltages beyond a threshold value. Finally, a two-step dielectrophoresis-assisted inertial microfluidics methodology was introduced for particle separation based on the crossover frequencies and the observed threshold voltages of different particles. The proposed method exploited the synergistic effect of dielectrophoresis and inertial microfluidics methods to remove their limitations, allowing the separation of a broad range of polydisperse particle mixtures with a single device in a short time.

3D Printed Microfluidic Bioreactors Used for the Preferential Growth of Bacterial Biofilms through Dielectrophoresis.

A realistic modelling of the way biofilms form and evolve in time requests a dynamic approach. In this study, the proposed route uses continuous-flow bioreactors under controlled flow rates and temperature in the culture medium containing bacteria or fungi. 3D printed, Polylactic acid (PLA), flow-based bioreactors with integrated copper electrodes were used to investigate the effect of dielectrophoresis on the formation and growth of Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853, and Klebsiella pneumoniae ATCC 13883 biofilms. Bacterial suspensions of 1McF turbidity have been prepared and circulated through the bioreactors. At the same time, a 30 V potential difference was applied on the system. The effect of the non-uniform electric field induced upon the bacterial cells was determined using quantitative methods, such as an adjusted microtiter plate technique, as well as spectral domain optical coherence tomography (SD-OCT) images. The morphology and the surface quality of the biofilms were investigated using Scanning Electron Microscopy (SEM) images. The results show that the different bacterial cells present a positive dielectrophoretic behaviour, with the preferential formation of biofilms in the high field gradient region.

Separation of Heterotrophic Microalgae Crypthecodinium cohnii by Dielectrophoresis.

Microalgae constitute an abundant source of poly-unsaturated fatty acids which are applied in various biotechnological fields such as pharmaceuticals and food supplement. Separating microalgae cells with respect to their lipid content would establish a relevant at-line analytical technique. The present study demonstrates an electrical approach for the separation of the lipid-producing microalgae Crypthecodinium cohnii using the effect of dielectrophoresis (DEP) in a microfluidic flow cell. Microalgae were cultivated for 8 days, while cell growth was characterized by optical density, dry cell weight, glucose concentration and lipid content via fluorescence microscopy. The size distribution of cells during cultivation was thoroughly investigated, since the DEP force scales with cell volume, but also depends on lipid content via cell electrophysiological constants. Thus, the challenge was to deconvolute one separation effect from the other, while the electrical cell constants of C. cohnii are not known yet. The DEP-dependent separation was realized by slanted top-bottom electrodes with the flowing cell suspension between them. Turning on the voltage deflected the cells from their initial path as determined by the streaming and thus changed their direction of flow. The separation efficiency of DEP was tested for various electrical field strengths and its performance was determined by quantitative analysis of optical and fluorescence videos. It could be shown for all size groups that the most lipid-containing cells were always subject to DEP separation and that the method is thus not only suitable for process analysis, but also for strain selection of the most productive cell lines.

Correction to: High‑speed abrasive flow composite polishing based on dielectrophoresis effect

Correction to: High‑speed abrasive flow composite polishing based on dielectrophoresis effect

High-speed abrasive flow composite polishing based on dielectrophoresis effect

High-speed abrasive flow composite polishing based on dielectrophoresis effect

Window with Electrostatic Protection against Dust, Smoke, and Viruses

The article analyzes the effect of dangerous aerosols on the human body. In order to purify the air from aerosols, the effect of an electric field on them is considered. The electric and dielectrophoretic forces acting on submicron particles in an inhomogeneous electric field of two parallel wires are calculated. It is shown that part of this field is identical to the field between the wire and the grounded plate electrode located in the middle between the wires. This allows using a known formula for the electric field of a two-wire line to calculate the field gradient and the effect of dielectrophoresis on neutral particles. Smoke and dust particles already carry a negative charge, and a more or less uniform electric field is enough to move them. To filter neutral water droplets infected with the virus, you need either a field with a large gradient or a corona discharge. The paper shows that the polarization of particles in an electric field causes the particles to stick together, and larger particles settle faster on the electrodes of the filter. The design of a transparent electrostatic precipitator is proposed, which can be used to protect indoor air from external smoke, dust, or viruses.

A microfluidic chip integrated with 3D sidewall electrodes and wavy microchannel for cell focusing and separation

Cell focusing and separation is a prerequisite for several biological applications. Among these technologies that can achieve the operation, dielectrophoresis (DEP) has been widely used due to its non-contact, label-free and easy-to-operate advantages. In this paper, we designed a microchip that integrates 3D electrodes and wavy microchannel for cell focusing and separation. The 3D electrodes act as not only the electrodes but also as the microchannel walls. The wavy microchannel enables 3D electrodes to generate electric field gradient required by DEP force in the entire microchannel. Cells can be focused and separated under the synergistic effect of DEP and fluidic forces. We have demonstrated the feasibility of the microchip through numerical simulations and experiments. And we validated our approach by demonstrating focusing and separation of A549 and HeLa cells. According to the electrical differences of cells, in the range of 61–99 kHz, the two types of cells can be focused into three streams under the action of positive and negative DEP force to achieve cell separation. With the increase of the voltage amplitude to 10 V, the width of the cell streams was focused to about 30 μm, which can improve the effect of cell separation, the separation efficiency of A549 and HeLa can reach 91.2% and 95.1%, respectively. The proposed microchip is expected to provide a new pathway for designing an effective cell focusing and separation platform.

Multi-particle interaction in AC electric field driven by dielectrophoresis force.

When the dielectrophoresis technology is used to manipulate micron-sized particles, the interaction between particles should not be ignored because of the particle-particle interaction. Especially, when multiple particles (number of particles is above 2) are simultaneously manipulated, the interaction between neighboring particles will affect the results of the manipulation. This research investigates the interaction of particles caused dielectrophoresis effect by the Arbitrary Lagrangian-Eulerian (ALE) method based on the hypothesis of the thin layer of the electric double layer at the microscale. The mathematics model can be solved simultaneously by the finite element method for the AC electric field, the flow field around the suspended particles and the particle mechanics at the micrometer scale. In this study, the particle conductivity and the direction of the electric field are investigated, we find that particle conductivity and electric field direction pose an impact on particle movement, and the research reveal the law of microparticle dielectrophoresis movement, which could offer theoretical and technology support to profoundly understand the precise manipulation of particles in microfluidic chips by the dielectrophoresis effect.

Feasibility Study on the Precision Polishing of Zirconia Ceramics with Magnetic Compound Fluid (MCF) Slurry Under the Assistance of Dielectrophoresis Effect

In this work, a new polishing method for zirconia ceramics was firstly proposed, which combined dielec-trophoresis effect with magnetic compound fluid polishing. A key experimental device was designed and constructed, and the influence behavior of dielectrophoresis phenomenon on the polishing efficiency, surface roughness and glossiness of zirconia ceramic workpiece were investigated. Also, the effects of voltage, electrode shape and electric field parameters on the polishing results were deeply discussed. The results showed that when the magnetic field was stronger, the polishing efficiency would become higher, while the surface quality of the workpiece getting worse. And the glossiness was positively correlated with the surface roughness. Moreover, the smaller the electrode shape and the larger the electric field gradient caused the better dielectrophoresis-assisted effect. It was indicated that when the electrode shape was a circle with a diameter of 20 mm and the voltage was 1500 V, the material removal efficiency was improved by 36.4% while ensuring the surface quality of zirconia ceramics.

Biosensors Based on SOI Nanowire Transistors for Biomedicine and Virusology

This article contains the results of research on the topical problem of highly sensitive express registration of biological objects using field-effect transistors with the surface open for analyte access, which are made based on silicon-on-insulator (SOI) films. The possibilities of dielectrophoretic effects for controlling the concentration of the analyte in the area of sensory elements are considered on the example of the indication of viruses of nuclear polyhedrosis and vaccinia. It is shown that the use of the dielectrophoresis (DEPh) effect makes it possible to solve (1) the key tasks for creating sensor systems: increasing the detecting ability, as well as exrtacting and verifying the signal from the target particles; and (2) the fundamental task: determining the charge state of the analyte in solutions without modifying the sensors’ surface. The problems and prospects of the mass application of nanowire (NW) biosensors, including those with the dielectrophoretic effect, in biotechnology, virology, etc., are discussed.

Dielectrophoresis assisted high-throughput detection system for multiplexed immunoassays

Digital ELISA is introduced as a novel platform with unique advantages for detecting multiple kinds of single-molecule in the sample. How to improve the sensitivity of detection is the direction of current related research. Here, we report an immunoassay method that applied electrokinetic effects to isolate the individual encoded beads and confine in micro-wells to improve the efficiency of cytokines detection simultaneously. The microfluidic design provided a non-uniform electric field to induce dielectrophoresis (DEP) force and to manipulate the beads. Two wavelengths of excitation light excited the encoded beads for simultaneous detection of reporters. The light was confined to the bottom slide via the principle of total internal reflection. Finally, the concentration of captured cytokines was obtained by picking up each bead from the image and then integrating the intensity of fluorescent light emitted from the reporters. The results demonstrated that the fill percentage of encoded beads was raised from 10-20% to 60–80% via DEP effect. By comparing the fluorescence color of the particle, itself and its surface, the concentration of four target cytokines, IL-2, IL-6, IL-10 and TNF-α, were calculated to the pg/ml level. The spike and recovery experiments verified the efficiency, more than 70% of the target molecules were captured. The reliability of our method was verified by flow cytometry as well. In conclusion, we expect the application of DEP can increase the sensitivity of digital ELISA for multiple rapid detection.

An Enhanced Electrocoagulation Process for the Removal of Fe and Mn from Municipal Wastewater Using Dielectrophoresis (DEP)

In this study the removal of Fe and Mn from primary treated municipal wastewater using a new electrode configuration in electrocoagulation was evaluated. The used electrode configuration induced a dielectrophoretic (DEP) force in the electrocoagulation process. The impact of the electrolysis time, electrodes spacing and applied current on the removal of Fe and Mn was evaluated. The maximum removal percentages of Fe and Mn were obtained using an electrolysis time of 60 min, an electrode spacing of 0.5 cm and an applied current of 800 mA. Under these operating conditions and using the new electrodes configuration, the Fe and Mn removals were 96.8% and 66%, respectively. The main advantage of using the DEP-induced electrode configuration was the minimal consumption of the electrodes. The new electrode configuration showed 42% less aluminum content in the reactor compared to the aluminum electrodes with no DEP effect. The energy consumption at the selected operation conditions was 4.88 kWh/m3. The experimental results were comparable with the simulation results achieved by the COMSOL software.

Simulation Guided Microfluidic Design for Multitarget Separation Using Dielectrophoretic Principle

Microfluidic technologies have emerged as a potential tool for point of care — diagnostics and therapeutics applications. Isolation of multi-targets (Cancer cells along with platelets, red blood cells (RBCs), white blood cells (WBCs), and antigen-presenting cells (APCs)) simultaneously is of great interest in drug discovery and medical diagnosis. By utilizing dielectrophoresis (DEP) effect inside the micro channel, several attempts were made to separate binary mixtures by precisely controlling and manipulating the motion of the particles. However, all of these methods limit its applicability for multi-target particle separation in a single run. In this paper, we attempt to develop a simulation model with novel electrode arrangements to isolate multiple particles using negative DEP. Our proposed model establishes criteria for separating micron-sized particle mixtures (3µm, 7µm, 15µm, 20µm, 25µm) with various electrode shapes, electrode potentials, inlet velocities, and channel widths. The device efficiency was evaluated for a triangular electrode, square-shaped electrode, and rectangular electrode under various practical design constraints. Our study demonstrates an optimum solution for effective separation of particle mixtures using triangular electrode arrangements (utilizing less voltage) and a wider channel of 300µm width that eventually avoid channel clogging issues due to cells inside main channel and collection channels. While evaluating the separation efficiency of the proposed design, we observe that platelets, RBCs, WBCs, APCs, and CTCs experienced distinct DEP force on each, allowing them to collect in different collection outlets without any cross-mixing. Hence our proposed design allows flexibility to the researchers working on DEP by using a wider channel with triangular electrode arrangements enabling them to fabricate the device under resource-limited constraints.

An Approach to Ring Resonator Biosensing Assisted by Dielectrophoresis: Design, Simulation and Fabrication.

The combination of extreme miniaturization with a high sensitivity and the potential to be integrated in an array form on a chip has made silicon-based photonic microring resonators a very attractive research topic. As biosensors are approaching the nanoscale, analyte mass transfer and bonding kinetics have been ascribed as crucial factors that limit their performance. One solution may be a system that applies dielectrophoretic forces, in addition to microfluidics, to overcome the diffusion limits of conventional biosensors. Dielectrophoresis, which involves the migration of polarized dielectric particles in a non-uniform alternating electric field, has previously been successfully applied to achieve a 1000-fold improved detection efficiency in nanopore sensing and may significantly increase the sensitivity in microring resonator biosensing. In the current work, we designed microring resonators with integrated electrodes next to the sensor surface that may be used to explore the effect of dielectrophoresis. The chip design, including two different electrode configurations, electric field gradient simulations, and the fabrication process flow of a dielectrohoresis-enhanced microring resonator-based sensor, is presented in this paper. Finite element method (FEM) simulations calculated for both electrode configurations revealed ∇E2 values above 1017 V2m−3 around the sensing areas. This is comparable to electric field gradients previously reported for successful interactions with larger molecules, such as proteins and antibodies.

Effect of dielectrophoresis on the coalescence of binary droplets under a non-uniform electric field

Electric field assisted coalescence has been widely applied to separate water from water/oil (W/O) emulsions in the petroleum industry because of its high efficiency and large throughput. Under a non-uniform electric field, the coalescence results from the combination of the dieilectrophoresis force and dipole–dipole attraction. In previous works, the non-uniform electric field was thought to be advantageous because the dielectrophoresis force pulls droplets to a certain place. However, it was shown in this work that different types of dielectrophoresis have different effects on coalescence. Positive dielectrophoresis had adverse effects on causing binary droplets to separate. However, negative dielectrophoresis had an advantageous effect. For positive dielectrophoresis, there is a critical distance of coalescence. The results showed that the critical distance decreases with an increase of the electric field intensity and continuous phase viscosity and also decreases with an increase of the diameter of the droplet in the lower position. Thus, a stronger electric field intensity and lower viscosity might be a disadvantage if the electric field is non-uniform. These conclusions are important supplements for the mechanism of non-uniform electric field assisted coalescence, which has significant guidance for the design of an electrocoalescer.

Multiple Particle Manipulation under Dielectrophoresis Effect: Modeling and Experiments.

The dissipative particle dynamics (DPD) technique was employed to design multiple microfluidic devices for investigating the motion of bioparticles at low Reynolds numbers. A DPD in-house FORTRAN code was developed to simulate the trajectories of two microparticles in the presence of hydrodynamic and transverse deflecting force fields via considering interparticle interaction forces. The particle-particle interactions were described by using a simplified version of the Morse potential. The transverse deflecting force considered in this microfluidic application was the dielectrophoresis (DEP) force. Multiple microfluidic devices with different configurations of microelectrodes were numerically designed to investigate the dielectrophoretic behavior of bioparticles for their trajectories and the focusing of bioparticles into a single stream in the middle of the microchannel. The DPD simulation results were verified and validated against previously reported numerical and experimental works in the literature. The computationally designed microdevices were fabricated by employing standard lithographic techniques, and experiments were conducted via taking red blood cells as the representative bioparticles. The experimental results for the trajectories and focusing showed good agreement with the numerical results.