Electro-Osmotic Flow in Reservoir-Connected Flat Microchannels With Non-Uniform Zeta Potential

The effects of non-uniform zeta potentials on electro-osmotic flows in flat microchannels have been investigated with particular attention to reservoir effects. The governing equations, which consist of a Laplace equation for the distribution of external electric potential, a Poisson equation for the distribution of electric double layer potential, the Nernst-Planck equation for the distribution of charge density, and modified Navier-Stokes equations for the flow field are solved numerically for an incompressible steady flow of a Newtonian fluid using the finite-volume method. For the validation of the numerical scheme, the key features of an ideal electro-osmotic flow with uniform zeta potential have been compared with analytical solutions for the ionic concentration, electric potential, pressure, and velocity fields. When reservoirs are included in the analysis, an adverse pressure gradient is induced in the channel due to entrance and exit effects even when the reservoirs are at the same pressure. Non-uniform zeta potentials lead to complex flow fields, which are examined in detail.

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Towards bio-inspired artificial muscle: a mechanism based on electro-osmotic flow simulated using dissipative particle dynamics

Scientific Reports ◽

10.1038/s41598-021-81608-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ramin Zakeri

Keyword(s):

Zeta Potential ◽

Electric Field ◽

Dissipative Particle Dynamics ◽

Artificial Muscle ◽

Particle Dynamics ◽

Polymer Membrane ◽

Channel Width ◽

Micro Channel ◽

Osmotic Flow ◽

Electro Osmotic Flow

AbstractOne of the unresolved issues in physiology is how exactly myosin moves in a filament as the smallest responsible organ for contracting of a natural muscle. In this research, inspired by nature, a model is presented consisting of DPD (dissipative particle dynamics) particles driven by electro-osmotic flow (EOF) in micro channel that a thin movable impermeable polymer membrane has been attached across channel width, thus momentum of fluid can directly transfer to myosin stem. At the first, by validation of electro-osmotic flow in micro channel in different conditions with accuracy of less than 10 percentage error compared to analytical results, the DPD results have been developed to displacement of an impermeable polymer membrane in EOF. It has been shown that by the presence of electric field of 250 V/m and Zeta potential − 25 mV and the dimensionless ratio of the channel width to the thickness of the electric double layer or kH = 8, about 15% displacement in 8 s time will be obtained compared to channel width. The influential parameters on the displacement of the polymer membrane from DPD particles in EOF such as changes in electric field, ion concentration, zeta potential effect, polymer material and the amount of membrane elasticity have been investigated which in each cases, the radius of gyration and auto correlation velocity of different polymer membrane cases have been compared together. This simulation method in addition of probably helping understand natural myosin displacement mechanism, can be extended to design the contraction of an artificial muscle tissue close to nature.

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Time-Periodic Electro-Osmotic Flow With Nonuniform Surface Charges

Journal of Fluids Engineering ◽

10.1115/1.4042469 ◽

2019 ◽

Vol 141 (8) ◽

Cited By ~ 1

Author(s):

Hyunsung Kim ◽

Aminul Islam Khan ◽

Prashanta Dutta

Keyword(s):

Zeta Potential ◽

Analytical Model ◽

Potential Distribution ◽

Step Change ◽

Creeping Flow ◽

Function Technique ◽

Osmotic Flow ◽

Nonuniform Surface ◽

Time Periodic ◽

Electro Osmotic Flow

Mixing in a microfluidic device is a major challenge due to creeping flow, which is a significant roadblock for development of lab-on-a-chip device. In this study, an analytical model is presented to study the fluid flow behavior in a microfluidic mixer using time-periodic electro-osmotic flow. To facilitate mixing through microvortices, nonuniform surface charge condition is considered. A generalized analytical solution is obtained for the time-periodic electro-osmotic flow using a stream function technique. The electro-osmotic body force term is accounted as a slip boundary condition on the channel wall, which is a function of time and space. To demonstrate the applicability of the analytical model, two different surface conditions are considered: sinusoidal and step change in zeta potential along the channel surface. Depending on the zeta potential distribution, we obtained diverse flow patterns and vortices. The flow circulation and its structures depend on channel size, charge distribution, and the applied electric field frequency. Our results indicate that the sinusoidal zeta potential distribution provides elliptical shaped vortices, whereas the step change zeta potential provides rectangular shaped vortices. This analytical model is expected to aid in the effective micromixer design.

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Applicability of electro-osmotic flow for the analysis of the surface zeta potential

RSC Advances ◽

10.1039/c9ra10414c ◽

2020 ◽

Vol 10 (12) ◽

pp. 6777-6789 ◽

Cited By ~ 2

Author(s):

Olivija Plohl ◽

Lidija Fras Zemljič ◽

Sanja Potrč ◽

Thomas Luxbacher

Keyword(s):

Zeta Potential ◽

Bulk Properties ◽

Electrokinetic Phenomena ◽

Osmotic Flow ◽

Electro Osmotic Flow

Detail comparison of two different electrokinetic phenomena EOF and SP method for the SZP determination with taking into account various materials with different surface and bulk properties.

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Thermal Effect on Microchannel Electro-osmotic Flow With Consideration of Thermodiffusion

Journal of Heat Transfer ◽

10.1115/1.4030240 ◽

2015 ◽

Vol 137 (9) ◽

Cited By ~ 4

Author(s):

Yi Zhou ◽

Yongqi Xie ◽

Chun Yang ◽

Yee Cheong Lam

Keyword(s):

Charge Density ◽

Thermal Effect ◽

Temperature Difference ◽

Electrical Potential ◽

Ionic Concentration ◽

Free Charge ◽

Regular Perturbation ◽

Osmotic Flow ◽

Ionic Distribution ◽

Electro Osmotic Flow

Electro-osmotic flow (EOF) is widely used in microfluidic systems. Here, we report an analysis of the thermal effect on EOF under an imposed temperature difference. Our model not only considers the temperature-dependent thermophysical and electrical properties but also includes ion thermodiffusion. The inclusion of ion thermodiffusion affects ionic distribution, local electrical potential, as well as free charge density, and thus has effect on EOF. In particular, we formulate an analytical model for the thermal effect on a steady, fully developed EOF in slit microchannel. Using the regular perturbation method, we solve the model analytically to allow for decoupling several physical mechanisms contributing to the thermal effect on EOF. The parametric studies show that the presence of imposed temperature difference/gradient causes a deviation of the ionic concentration, electrical potential, and electro-osmotic velocity profiles from their isothermal counterparts, thereby giving rise to faster EOF. It is the thermodiffusion induced free charge density that plays a key role in the thermodiffusion induced electro-osmotic velocity.

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Electro-osmotic flow in microchannels

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes784 ◽

2008 ◽

Vol 222 (5) ◽

pp. 753-759 ◽

Cited By ~ 7

Author(s):

A K Arnold ◽

P Nithiarasu ◽

P F Eng

Keyword(s):

Stokes Equations ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Driven Systems ◽

Osmotic Flow ◽

Poisson Boltzmann ◽

Wafer Surfaces ◽

Flow Experiments ◽

Complex Eof ◽

Electro Osmotic Flow

In the current study, the modified Navier—Stokes equations together with the Poisson—Boltzmann and Laplace equations have been used to numerically model electro-osmotic flow (EOF) in straight microchannels. Flow experiments have been carried out using microchannels etched into silicon wafer surfaces. The numerical results from the present study have been compared against experimental data and an analytical solution. The results indicate that the numerical simulations are an accurate representation of EOF and that this model could be used as a tool in the design and analysis of complex EOF driven systems.

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Streaming Electric Potential in Pressure-Driven Flows Through Reservoir-Connected Microchannels

Journal of Fluids Engineering ◽

10.1115/1.2776967 ◽

2007 ◽

Vol 129 (10) ◽

pp. 1346-1357 ◽

Cited By ~ 10

Author(s):

S. A. Mirbozorgi ◽

H. Niazmand ◽

M. Renksizbulut

Keyword(s):

Zeta Potential ◽

Electric Potential ◽

Stokes Equations ◽

Fundamental Problem ◽

Electrical Power ◽

Applied Pressure ◽

Streaming Potential ◽

Electrical Current ◽

Electrokinetic Flow ◽

Pressure Driven

Electrical power generation employing pressure-driven flows is a fundamental problem in microfluidics. In the present work, analytical and numerical analyses are performed to study the interplaying effects of electrolyte motion with the associated electrical current in a flat microchannel with and without fluid reservoirs. The modified Navier–Stokes equations as well as a Poisson equation for the distribution of electric potential and the Nernst–Planck equations for the distribution of charge densities are solved for the steady flow of a Newtonian liquid. The results show that for a pressure-driven flow, an electric potential is induced due to the motion of charged particles, which increases linearly along the microchannel. This streaming potential generates an opposing conduction current in the core region of the channel as well as in the immediate vicinity of the walls, where the streaming current is negligible. The streaming potential varies in a nonlinear manner with the zeta potential at the walls such that a maximum potential exists at a certain zeta potential. The maximum potential is also observed to increase with both the applied pressure difference and the electric double layer thickness in the range studied. The presence of reservoirs adds significant complexity to this electrokinetic flow.

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Numerical Analysis of a T-Type Electrokinetic Micromixer With Heterogeneous Zeta Potentials and Viscoelectric Effects

Volume 10: Fluids Engineering ◽

10.1115/imece2020-23425 ◽

2020 ◽

Author(s):

Juan P. Escandón ◽

David A. Torres

Keyword(s):

Zeta Potential ◽

Concentration Field ◽

Mass Conservation ◽

Ionic Concentration ◽

Wave Number ◽

Correct Selection ◽

Mixing Efficiency ◽

Fluid Viscosity ◽

Zeta Potentials ◽

Sinusoidal Functions

Abstract This paper presents the 2-D numerical solution of the flow and concentration field of an electrokinetic T-type micromixer, under heterogeneous zeta potentials modulated via sinusoidal functions and interfacial viscoelectric effects. Here, the viscoelectric effects appear to modify the fluid viscosity due to the high voltages within the electric double layer. The mathematical model is based on the Poisson-Boltzmann, mass conservation, momentum, and species concentration equations. In the steady-state analysis, two electrolytes with known ionic concentration and an imposed velocity profile are considered at the inlet of the micromixer. The results demonstrate that by using heterogeneous zeta potentials, at the mixer walls, generated flow recirculations along the mixer channel, promoting the rise in mixing efficiency; however, for high zeta potential values, this is counteracted by the viscoelectric effects. The present investigation shows how the viscoelectric condition deteriorates the mixing performance and how with the correct selection of modulated zeta potential parameters as the wave number, and the phase angle can improve it. Therefore, the performance of the mixer studied here should be considered for the design of microfluidic devices in the future.

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Measurement of Zeta-potential of Electro-osmotic Flow Inside a Micro-channel

Transactions of the Korean Society of Mechanical Engineers B ◽

10.3795/ksme-b.2006.30.10.935 ◽

2006 ◽

Vol 30 (10) ◽

pp. 935-941 ◽

Cited By ~ 1

Author(s):

Su-Dong Han ◽

Sang-Joon Lee

Keyword(s):

Zeta Potential ◽

Micro Channel ◽

Osmotic Flow ◽

Electro Osmotic Flow

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Study of three-dimensional electro-osmotic flow with curved boundary via lattice Boltzmann method

International Journal of Modern Physics C ◽

10.1142/s0129183116500637 ◽

2016 ◽

Vol 27 (06) ◽

pp. 1650063 ◽

Cited By ~ 5

Author(s):

Q. Chen ◽

X. B. Zhang ◽

Q. Li ◽

X. S. Jiang ◽

H. P. Zhou

Keyword(s):

Electric Field ◽

Flow Velocity ◽

Electric Potential ◽

Lattice Boltzmann ◽

Potential Distribution ◽

Three Dimensional ◽

Ionic Concentration ◽

Curved Boundary ◽

Sphere Radius ◽

Electro Osmotic Flow

A three-dimensional (3D) lattice Boltzmann model and boundary method is developed to simulate electro-osmotic flow (EOF) with a charged spherical particle immersed in an electrolyte solution. The general governing equations for electro-osmotic transport are Navier–Stokes equations for fluid flow and the Poisson–Boltzmann equation for electric potential distribution around the particle. Two sets of D3Q19 lattice structure with curved boundary conditions are implemented. The simulation results are compared with analytical predictions and are found to be in excellent agreement. The potential distribution appears circularly symmetric and the flow velocity decreases with the cross-sectional area for flow passage increasing due to the mass conservation. The effects of the ionic concentration, the sphere radius, electric potential and external electric field on the velocity profiles are investigated. The flow velocity increases with both the electric potential and the external electric field. However, the variation in flow velocity with the ionic concentration and the sphere radius is complex due to the change in electrical double layer (EDL) thickness.

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