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

2006 ◽  
Vol 30 (10) ◽  
pp. 935-941 ◽  
Author(s):  
Su-Dong Han ◽  
Sang-Joon Lee
Keyword(s):  
Zeta Potential ◽  
Micro Channel ◽  
Osmotic Flow ◽  
Electro Osmotic Flow

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

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.

Numerical investigation on pressure-driven electro osmatic flow and mixing in a constricted micro channel by triangular obstacle

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahamed Saleel C. ◽  
Asif Afzal ◽  
Irfan Anjum Badruddin ◽  
T.M. Yunus Khan ◽  
Sarfaraz Kamangar ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Mixing Efficiency ◽  
Micro Channel ◽  
Wall Surface ◽  
Content Type ◽  
Osmotic Flow ◽  
Boundary Method ◽  
Electro Osmotic Flow

Purpose The characteristics of fluid motions in micro-channel are strong fluid-wall surface interactions, high surface to volume ratio, extremely low Reynolds number laminar flow, surface roughness and wall surface or zeta potential. Due to zeta potential, an electrical double layer (EDL) is formed in the vicinity of the wall surface, namely, the stern layer (layer of immobile ions) and diffuse layer (layer of mobile ions). Hence, its competent designs demand more efficient micro-scale mixing mechanisms. This paper aims to therefore carry out numerical investigations of electro osmotic flow and mixing in a constricted microchannel by modifying the existing immersed boundary method. Design/methodology/approach The numerical solution of electro-osmotic flow is obtained by linking Navier–Stokes equation with Poisson and Nernst–Planck equation for electric field and transportation of ion, respectively. Fluids with different concentrations enter the microchannel and its mixing along its way is simulated by solving the governing equation specified for the concentration field. Both the electro-osmotic effects and channel constriction constitute a hybrid mixing technique, a combination of passive and active methods. In microchannels, the chief factors affecting the mixing efficiency were studied efficiently from results obtained numerically. Findings The results indicate that the mixing efficiency is influenced with a change in zeta potential (ζ), number of triangular obstacles, EDL thickness (λ). Mixing efficiency decreases with an increment in external electric field strength (Ex), Peclet number (Pe) and Reynolds number (Re). Mixing efficiency is increased from 28.2 to 50.2% with an increase in the number of triangular obstacles from 1 to 5. As the value of Re and Pe is decreased, the overall percentage increase in the mixing efficiency is 56.4% for the case of a mixing micro-channel constricted with five triangular obstacles. It is also vivid that as the EDL overlaps in the micro-channel, the mixing efficiency is 52.7% for the given zeta potential, Re and Pe values. The findings of this study may be useful in biomedical, biotechnological, drug delivery applications, cooling of microchips and deoxyribonucleic acid hybridization. Originality/value The process of mixing in microchannels is widely studied due to its application in various microfluidic devices like micro electromechanical systems and lab-on-a-chip devices. Hence, its competent designs demand more efficient micro-scale mixing mechanisms. The present study carries out numerical investigations by modifying the existing immersed boundary method, on pressure-driven electro osmotic flow and mixing in a constricted microchannel using the varied number of triangular obstacles by using a modified immersed boundary method. In microchannels, the theory of EDL combined with pressure-driven flow elucidates the electro-osmotic flow.

Modeling electro-osmotic flow and thermal transport of Caputo fractional Burgers fluid through a micro-channel

2021 ◽  
pp. 095440892110259
Author(s):  
Mohammed Abdulhameed ◽  
Garba Tahiru Adamu ◽  
Gulibur Yakubu Dauda
Keyword(s):  
Electric Field ◽  
Laplace Transform ◽  
Inverse Laplace Transform ◽  
Micro Channel ◽  
Osmotic Flow ◽  
Sine Transform ◽  
Fourier Sine ◽  
Fourier Sine Transform ◽  
Burgers Fluid ◽  
Electro Osmotic Flow

In this paper, we construct transient electro-osmotic flow of Burgers’ fluid with Caputo fractional derivative in a micro-channel, where the Poisson–Boltzmann equation described the potential electric field applied along the length of the microchannel. The analytical solution for the component of the velocity profile was obtained, first by applying the Laplace transform combined with the classical method of partial differential equations and, second by applying Laplace transform combined with the finite Fourier sine transform. The exact solution for the component of the temperature was obtained by applying Laplace transform and finite Fourier sine transform. Further, due to the complexity of the derived models of the governing equations for both velocity and temperature, the inverse Laplace transform was obtained with the aid of numerical inversion formula based on Stehfest's algorithms with the help of MATHCAD software. The graphical representations showing the effects of the time, retardation time, electro-kinetic width, and fractional parameters on the velocity of the fluid flow and the effects of time and fractional parameters on the temperature distribution in the micro-channel were presented and analyzed. The results show that the applied electric field, electro-osmotic force, electro-kinetic width, and relaxation time play a vital role on the velocity distribution in the micro-channel. The fractional parameters can be used to regulate both the velocity and temperature in the micro-channel. The study could be used in the design of various biomedical lab-on-chip devices, which could be useful for biomedical diagnosis and analysis.

Time-Periodic Electro-Osmotic Flow With Nonuniform Surface Charges

2019 ◽  
Vol 141 (8) ◽  
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.

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

RSC Advances ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 6777-6789 ◽  
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.

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

2006 ◽  
Vol 128 (6) ◽  
pp. 1133-1143 ◽  
Author(s):  
S. A. Mirbozorgi ◽  
H. Niazmand ◽  
M. Renksizbulut
Keyword(s):  
Zeta Potential ◽  
Electric Potential ◽  
Stokes Equations ◽  
Planck Equation ◽  
Ionic Concentration ◽  
Complex Flow ◽  
Layer Potential ◽  
Osmotic Flow ◽  
Zeta Potentials ◽  
Electro Osmotic Flow

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.

Enhanced Electro-Osmotic Flow Pump for Micro-Scale Heat Exchangers

2012 ◽  
Author(s):  
Marwan F. Al-Rjoub ◽  
Ajit K. Roy ◽  
Sabyasachi Ganguli ◽  
Rupak K. Banerjee
Keyword(s):  
Thermal Management ◽  
Flow Rate ◽  
Hot Spots ◽  
Nano Particles ◽  
Distilled Water ◽  
Micro Channel ◽  
Osmotic Flow ◽  
Micro Pump ◽  
Improved Design ◽  
Electro Osmotic Flow

Non-uniform heat flux generated by microchips can create “hot spots” in localized areas on the microchip surface. This research presents an improved design of an active cooling electro-osmotic flow (EOF) based micro-pump for hot spots thermal management. The design of the micro-pump was simpler and more practical for the application compared to designs presented in literature. Most micro-channel heat sink devices presented in literature were silicon based. Though silicon has better thermal conductivity when compared to polymers used in micro-devices fabrication, processes of silicon fabrication are complicated and time consuming. Also, most micro-channel fabrication processes use silicon etching which leads to rough walls within the micro-channel. An improved design, which uses a combination of silicon and Polydimethylsiloxane (PDMS), is being developed and tested. The main idea of this design is to utilize the favorable thermal properties of silicon while achieving both smoother charged surfaces and ease of fabrication of PDMS material. The EOF micro-pump was tested for four cooling fluid namely, DI water, distilled water, borax buffer, and Al2O3 nano-particles suspended in water solution. A maximum flow rate of 31.2 μL/min was achieved using distilled water at 500 V of EOF voltage. Such micro-pump with this flow rate range can be implemented in a closed loop heat rejection system for hot spot thermal management. Moreover, it can be used in Lap-on-chip and uTAS application for sample transport.

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