Electroosmotic Flow In Microchannels Research Articles

CHARACTERIZATION OF ELECTROOSMOTIC FLOW IN MICROCHANNELS

This paper presents experimental and theoretical studies of the electroosmotic flow in microchannels. The current monitoring method is used to determine the average flow velocity and the ζ potential by measuring the current-time relationship during electrolyte displacement process. A rigorous mathematical model is developed to describe the electrokinetic transport phenomena in such displacement process. Experiments were carried out for the NaCl electrolyte to evaluate the electroosmotic velocity and the ζ potential under various experimental conditions. The theoretical predictions for the current-time relationship are compared with measured results.

NUMERICAL STUDIES OF DEVELOPING FLOW IN MICROCHANNEL

International Journal of Computational Engineering ScienceVol. 04, No. 02, pp. 389-392 (2003) Design, Modelling and SimulationNo AccessNUMERICAL STUDIES OF DEVELOPING FLOW IN MICROCHANNELS. T. TAN and E. Y. K. NGS. T. TANFerrotec Corporation, Kallang Basin Industrial estate, Singapore 339412, SingaporeSchool of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue Singapore 639798, Singapore Search for more papers by this author and E. Y. K. NGSchool of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue Singapore 639798, Singapore Search for more papers by this author https://doi.org/10.1142/S1465876303001344Cited by:6 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractMicrochannels have the potential to be ultra compact, very efficient heat exchangers, which capitalize on the large surface area to volume ratio of the channels, to transport high heat fluxes with small thermal resistance. This paper describes a 3-D developing flow model by using Navier stoke equations with electric double layer (EDL) effect to model the flow field in microchannel. The electric potential distribution is simulated using a Poisson-Boltzmann equation. Results comparing the performances of the microchannel under different nondimensionalized electric potential are shown and discussed. Nusselt numbers for each case such as with or without EDL effect is also calculated; so that the actual effectiveness of the micro-channel can be understand.Keywords:numericaldeveloping flowmicrochannelEDLNavier-Stoke References G. M. Mala, D. Li and J. D. Dale, Int. J. Heat Mass Transfer 40(13), 3079 (1997). Crossref, Google ScholarE. Y. K. Ng and S. T. Poh, Journal of Computer Modeling in Engineering & Sciences 3(3), 351 (2002). Google ScholarC. Yang, D. Li and J. H. Masliyah, International Journal of Heat and Mass Transfer 41, 4229 (1998). Crossref, Google Scholar S. V. Patankar , Numerical heat transfer and fluid flow ( McGraw-Hill , New York , 1980 ) . Crossref, Google Scholar FiguresReferencesRelatedDetailsCited By 6A NOVEL INVESTIGATION OF HEAT TRANSFER CHARACTERISTICS IN HYBRID MICRO-CHANNEL HEAT SINK STRUCTURE: OPPOSITION-BASED ANTLION OPTIMIZATIONR. DEENA and G. SAI SUNDARA KRISHNAN22 August 2019 | Surface Review and Letters, Vol. 27, No. 05Study of EDL effect on 3-D developing flow in microchannel with Poisson–Boltzmann and Nernst–Planck modelsE. Y. K. Ng and S. T. Tan1 January 2007 | International Journal for Numerical Methods in Engineering, Vol. 71, No. 7LATTICE BOLTZMANN SIMULATION OF VISCOUS DISSIPATION IN ELECTRO-OSMOTIC FLOW IN MICROCHANNELSZHEN-HUA CHAI, BAO-CHANG SHI, and LIN ZHENG21 November 2011 | International Journal of Modern Physics C, Vol. 18, No. 07Simulation of electro-osmotic flow in microchannel with lattice Boltzmann methodZhenhua Chai and Baochang Shi1 Apr 2007 | Physics Letters A, Vol. 364, No. 3-4Numerical Analysis of EDL Effect on Heat Transfer Characteristic of 3-D Developing Flow in a MicrochannelS. T. Tan and E. Y. K. Ng22 September 2006 | Numerical Heat Transfer, Part A: Applications, Vol. 49, No. 10Computational studies of the EDL effect in 3-D developing flow in microchannelS T Tan and E Y K Ng25 April 2006 | Journal of Physics: Conference Series, Vol. 34 Recommended Vol. 04, No. 02 Metrics History Keywordsnumericaldeveloping flowmicrochannelEDLNavier-StokePDF download

Effect of analyte adsorption on the electroosmotic flow in microfluidic channels.

The predictability and constancy over time of the electroosmotic flow in microchannels is an important consideration in microfluidic devices. A common cause for alteration of the flow is the adsorption of analytes to channel walls, for example, during capillary electrophoresis of proteins. It is shown that certain experimental data, published by Towns and Regnier (Towns, J. K; Regnier, F. E. Anal. Chem. 1992, 64, 2473-2478.), on the anomalous elution times for proteins in capillary electrophoresis can be explained using a simple model for analyte adsorption that uses a result first reported by Anderson and Idol (Anderson, J. L.; Idol, W. K Chem. Eng. Commun. 1985, 38, 93-106.) on the electroosmotic flux in capillaries with axial variations in zeta-potential. It is suggested that it might be possible to use such a model to dynamically correct for altered elution times in capillary electrophoretic devices.

Active control of electroosmotic flow in microchannels using light

The ability to control bulk electroosmotic flow in microchannels via light modulation is demonstrated. Microchannels (1000 μm wide, 20 μm deep) were fabricated and a TiO 2 film was deposited on the inner walls of the channel. TiO 2 is a direct semiconductor that exhibits a change in surface charge upon radiation with UV light; leading to variations in the zeta potential and subsequent flow modulation. The bulk velocity was measured using the current monitoring technique in the presence and absence of UV radiation. Phosphate buffer solutions of different pH values (2.2, 4.7, 8.4) were tested. The magnitude of the change in velocity due to irradiation varied from 7 to 242 μm/s depending on the pH of the buffer. The largest velocity change was observed at pH 4.7, with smaller changes observed at higher and lower pH values. Parameters influencing flow velocity are also discussed.

Electroosmotic flows in microchannels with finite inertial and pressure forces.

Emerging microfluidic systems have spurred an interest in the study of electrokinetic flow phenomena in complex geometries and a variety of flow conditions. This paper presents an analysis of the effects of fluid inertia and pressure on the velocity and vorticity field of electroosmotic flows. In typical on-chip electrokinetics applications, the flow field can be separated into an inner flow region dominated by viscous and electrostatic forces and an outer flow region dominated by inertial and pressure forces. These two regions are separated by a slip velocity condition determined by the Helmholtz-Smoulochowski equation. The validity of this assumption is investigated by analyzing the velocity field in a pressure-driven, two-dimensional flow channel with an impulsively started electric field. The regime for which the inner/outer flow model is valid is described in terms of nondimensional parameters derived from this example problem. Next, the inertial forces, surface conditions, and pressure-gradient conditions for a full-field similarity between the electric and velocity fields in electroosmotic flows are discussed. A sufficient set of conditions for this similarity to hold in arbitrarily shaped, insulating wall microchannels is the following: uniform surface charge, low Reynolds number, low Reynolds and Strouhal number product, uniform fluid properties, and zero pressure differences between inlets and outlets. Last, simple relations describing the generation of vorticity in electroosmotic flow are derived using a wall-local, streamline coordinate system.