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Tavari T, Meamardoost S, Sepehry N, Akbarzadeh P, Nazari M, Hashemi NN, Nazari M. Effects of 3D electrodes arrangement in a novel AC electroosmotic micropump: Numerical modeling and experimental validation. Electrophoresis 2023; 44:450-461. [PMID: 36448415 DOI: 10.1002/elps.202200215] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/07/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022]
Abstract
To date, a comprehensive systematic optimization framework, capable of accurately predicting an efficient electrode geometry, is not available. Here, different geometries, including 3D step electrodes, have been designed in order to fabricate AC electroosmosis micropumps. It is essential to optimize both geometrical parameters of electrode, such as width and height of steps on each base electrode and their location in one pair, the size of each base electrode (symmetric or asymmetric), the gap of electrode pairs, and nongeometrical parameters such as fluid flow in a channel and electrical characteristics (e.g., frequency and voltage). The governing equations comprising of electric domain and fluid domain have been coupled using finite element method. The developed model was employed to investigate the effect of electrode geometric parameters on electroosmotic slip velocity and its subsequent effect on pressure and flow rate. Numerical simulation indicates that the optimal performance can be achieved using a design with varying step height and displacement, at a given voltage (2.5 V) and frequency (1 kHz). Finally, in order to validate the numerical simulation, the optimal microchip was fabricated using a combination of photolithography, electroplating, and a polydimethylsiloxane microchannel. Our results indicate that our micropump is capable of generating a pressure, velocity, and flow rate of 74.2 Pa, 1.76 mm/s, and 14.8 µl/min, respectively. This result reveals that our proposed geometry outperforms the state-of-the-art micropumps previously reported in the literature by improving the fluid velocity by 32%, with 80% less electrodes per unit length, and whereas the channel length is ∼80% shorter.
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Affiliation(s)
- Tannaz Tavari
- Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
| | - Saber Meamardoost
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York, USA
| | - Naserodin Sepehry
- Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
| | - Pooria Akbarzadeh
- Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
| | - Mostafa Nazari
- Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
| | - Nicole N Hashemi
- Department of Mechanical Engineering, Iowa State University, Ames, Iowa, USA
| | - Mohsen Nazari
- Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
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2
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M Boymelgreen A, Kunti G, Garcia-Sanchez P, Ramos A, Yossifon G, Miloh T. The role of particle-electrode wall interactions in mobility of active Janus particles driven by electric fields. J Colloid Interface Sci 2022; 616:465-475. [PMID: 35421638 DOI: 10.1016/j.jcis.2022.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/19/2022] [Accepted: 02/04/2022] [Indexed: 11/29/2022]
Abstract
HYPOTHESIS The interaction of active particles with walls can explain discrepancies between experiments and theory derived for particles in the bulk. For an electric field driven metallodielectric Janus particle (JP) adjacent to an electrode, interaction between the asymmetric particle and the partially screened electrode yields a net electrostatic force - termed self-dielectrophoresis (sDEP) - that competes with induced-charge electrophoresis (ICEP) to reverse particle direction. EXPERIMENTS The potential contribution of hydrodynamic flow to the reversal is evaluated by visualizing flow around a translating particle via micro-particle image velocimetry and chemically suppressing ICEP with poly(l-lysine)-g-poly(ethylene glycol) (PLL-PEG). Mobility of Polystyrene-Gold JPs is measured in KCl electrolytes of varying concentration and with a capacitive SiO2 coating at the metallic JP surface or electrode. Results are compared with theory and numerical simulations accounting for electrode screening. FINDINGS PLL-PEG predominantly suppresses low-frequency mobility where propulsive electro-hydrodynamic jetting is observed; supporting the hypothesis of an electrostatic driving force at high frequencies. Simulations and theory show the magnitude, direction and frequency dispersion of JP mobility are obtained by superposition of ICEP and sDEP using the JP height and capacitance as fitting parameters. Wall proximity enhances ICEP and sDEP and manifests a secondary ICEP charge relaxation time dominating in the contact limit.
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Affiliation(s)
- A M Boymelgreen
- Department of Mechanical and Materials Engineering, Florida International University, Miami, FL, 33174, USA.
| | - G Kunti
- Department of Mechanical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa, 3200003, Israel
| | - P Garcia-Sanchez
- Departamento de Electrónica y Electromagnetismo, Facultad de Física, Universidad de Sevilla, Avenida Reina Mercedes s/n, Sevilla 41012, Spain
| | - A Ramos
- Departamento de Electrónica y Electromagnetismo, Facultad de Física, Universidad de Sevilla, Avenida Reina Mercedes s/n, Sevilla 41012, Spain
| | - G Yossifon
- Department of Mechanical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa, 3200003, Israel
| | - T Miloh
- Department of Mechanical Engineering, Tel Aviv University, Ramat Aviv 6997801, Israel
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Baños R, Arcos J, Bautista O, Méndez F. Steric and Slippage Effects on Mass Transport by Using an Oscillatory Electroosmotic Flow of Power-Law Fluids. MICROMACHINES 2021; 12:mi12050539. [PMID: 34068510 PMCID: PMC8151737 DOI: 10.3390/mi12050539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 11/16/2022]
Abstract
In this paper, the combined effect of the fluid rheology, finite-sized ions, and slippage toward augmenting a non-reacting solute's mass transport due to an oscillatory electroosmotic flow (OEOF) is determined. Bikerman's model is used to include the finite-sized ions (steric effects) in the original Poisson-Boltzmann (PB) equation. The volume fraction of ions quantifies the steric effects in the modified Poisson-Boltzmann (MPB) equation to predict the electrical potential and the ion concentration close to the charged microchannel walls. The hydrodynamics is affected by slippage, in which the slip length was used as an index for wall hydrophobicity. A conventional finite difference scheme was used to solve the momentum and species transport equations in the lubrication limit together with the MPB equation. The results suggest that the combined slippage and steric effects promote the best conditions to enhance the mass transport of species in about 90% compared with no steric effect with proper choices of the Debye length, Navier length, steric factor, Womersley number, and the tidal displacement.
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Affiliation(s)
- Ruben Baños
- Instituto Politécnico Nacional, ESIME Azcapotzalco, Av. de las Granjas No. 682, Col. Santa Catarina, Del. Azcapotzalco, Ciudad de México 02250, Mexico;
| | - José Arcos
- Instituto Politécnico Nacional, ESIME Azcapotzalco, Av. de las Granjas No. 682, Col. Santa Catarina, Del. Azcapotzalco, Ciudad de México 02250, Mexico;
- Correspondence: (J.A.); (O.B.)
| | - Oscar Bautista
- Instituto Politécnico Nacional, ESIME Azcapotzalco, Av. de las Granjas No. 682, Col. Santa Catarina, Del. Azcapotzalco, Ciudad de México 02250, Mexico;
- Correspondence: (J.A.); (O.B.)
| | - Federico Méndez
- Departamento de Termofluidos, Facultad de Ingeniería, UNAM, Ciudad de México 04510, Mexico;
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Mehta SK, Pati S, Mondal PK. Numerical study of the vortex-induced electroosmotic mixing of non-Newtonian biofluids in a nonuniformly charged wavy microchannel: Effect of finite ion size. Electrophoresis 2021; 42:2498-2510. [PMID: 33527431 DOI: 10.1002/elps.202000225] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 11/11/2022]
Abstract
We propose a micromixer for obtaining better efficiency of vortex induced electroosmotic mixing of non-Newtonian bio-fluids at a relatively higher flow rate, which finds relevance in many biomedical and biological applications. To represent the rheology of non-Newtonian fluid, we consider the Carreau model in this study, while the applied electric field drives the constituent components in the micromixer. We show that the spatial variation of the applied field, triggered by the topological change of the bounding surfaces, upon interacting with the non-uniform surface potential gives rise to efficient mixing as realized by the formation of vortices in the proposed micromixer. Also, we show that the phase-lag between surface potential leads to the formation of asymmetric vortices. This behavior offers better mixing performance following the appearance of undulation on the flow pattern. Finally, we establish that the assumption of a point charge in the paradigm of electroosmotic mixing, which is not realistic as well, under-predicts the mixing efficiency at higher amplitude of the non-uniform zeta potential. The inferences of the present analysis may guide as a design tool for micromixer where rheological properties of the fluid and flow actuation parameters can be simultaneously tuned to obtain phenomenal enhancement in mixing efficiency.
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Affiliation(s)
- Sumit Kumar Mehta
- Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar, 788010, India
| | - Sukumar Pati
- Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar, 788010, India
| | - Pranab Kumar Mondal
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039, India
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Gopmandal PP, De S, Bhattacharyya S, Ohshima H. Impact of ion-steric and ion-partitioning effects on electrophoresis of soft particles. Phys Rev E 2020; 102:032601. [PMID: 33075919 DOI: 10.1103/physreve.102.032601] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/12/2020] [Indexed: 11/07/2022]
Abstract
A theoretical study on the electrophoresis of a soft particle is made by taking into account the ion steric interactions and ion partitioning effects under a thin Debye layer consideration with negligible surface conduction. Objective of this study is to provide a simple expression for the mobility of a soft particle which accounts for the finite-ion-size effect and the ion partitioning arise due to the Born energy difference between two media. The Donnan potential in the soft layer is determined by considering the ion steric interactions and the ion partitioning effect. The volume exclusion due to the finite ion size is considered by the Carnahan-Starling equation and the ion partitioning is accounted through the difference in Born energy. The modified Poisson-Boltzmann equation coupled with Stokes-Darcy-Brinkman equations are considered to determine the mobility. A closed-form expression for the electrophoretic mobility is obtained, which reduces to several existing expressions for mobility under various limiting cases.
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Affiliation(s)
- Partha P Gopmandal
- Department of Mathematics, National Institute of Technology Durgapur, Durgapur 713209, India
| | - Simanta De
- Department of Mathematics, University of Gour Banga, Malda 732103, India
| | - S Bhattacharyya
- Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - H Ohshima
- Faculty of Pharmaceutical Sciences, Tokyo University of Science Noda, Chiba 278-8510, Japan
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6
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Yao Y, Wen C, Pham NH, Zhang SL. On Induced Surface Charge in Solid-State Nanopores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8874-8882. [PMID: 32646217 DOI: 10.1021/acs.langmuir.0c01189] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Solid-state nanopores constitute a versatile platform for study of ion transport in nanoconfinement. The electrical double layer (EDL) plays a vital role in such nanoconfinements, but effects of induced surface charge on the EDL in the presence of an external transmembrane electric field are yet to be characterized. Here, the formation of induced charge on the nanopore sidewall surface and its effects, via modulation of the EDL and electroosmotic flow, on the ionic current are elucidated using a novel experimental setup with solid-state truncated-pyramidal nanopores. This study consists of three complementary approaches, i.e., an analytical model for induced surface charge, numerical simulation of induced surface charge, electroosmotic flow, and ionic current, and experimental validation with respect to the ionic current. The induced surface charge is generated by polarization in the dielectric membrane as a response to the applied electric field. This charge generation results in a nonuniform density of surface charge along the nanopore sidewall. It further causes ions in the electrolyte to redistribute, leading to a massive accumulation of single-polarity ions in the EDL and their counterions near the smaller opening of the nanopore. It also alters electrohydrodynamic properties in the nanopore, giving rise to the formation of electroosmotic vortexes in the vicinity of the smaller opening of the nanopore. Finally, the pattern of the electroosmotic flow can significantly influence the transport properties of the nanopore.
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Affiliation(s)
- Yao Yao
- Division of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
| | - Chenyu Wen
- Division of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
| | - Ngan H Pham
- Division of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
| | - Shi-Li Zhang
- Division of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
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7
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Recent advancement in induced-charge electrokinetic phenomena and their micro- and nano-fluidic applications. Adv Colloid Interface Sci 2020; 280:102159. [PMID: 32344205 DOI: 10.1016/j.cis.2020.102159] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/11/2020] [Accepted: 04/12/2020] [Indexed: 11/21/2022]
Abstract
Induced-charge electrokinetics (ICEK) remains a hot topic due to its promising applications in micro- and nano-fluidics. Over the past decade, researchers have made a great advancement in both fundamental studies and application developments. They captured (I) a flow reversal in induced-charge electroosmosis (ICEO) and attributed it to the phase delay effect of ions, (II) a chaotic ICEO and attributed it to the concentration polarization in the bulk solution, (III) a non-quadratic correlation for ICEO of non-Newtonian fluids and attributed it to the power-law viscosity, (IV) an induced-charge electrophoretic (ICEP) rotation of Janus doublets, etc. Furthermore, various ICEK-based micro- and nano-fluidic devices have been developed, namely, micropumps, particle focusers, trappers, sorters, and nanopore ion diodes. The present article provides a comprehensive review on the recent advancement of ICEK. Firstly, the fundamental studies of ICEK are introduced; then the micro- and nano-fluidic applications based on ICEK are presented; lastly, promising future directions for both fundamental and applications are discussed. This review presents the basic framework of ICEK, and can facilitate the development of ICEK-based applications.
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Shen C, Jiang Z, Li L, Gilchrist JF, Ou-Yang HD. Frequency Response of Induced-Charge Electrophoretic Metallic Janus Particles. MICROMACHINES 2020; 11:mi11030334. [PMID: 32213879 PMCID: PMC7142510 DOI: 10.3390/mi11030334] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 03/19/2020] [Accepted: 03/21/2020] [Indexed: 12/23/2022]
Abstract
The ability to manipulate and control active microparticles is essential for designing microrobots for applications. This paper describes the use of electric and magnetic fields to control the direction and speed of induced-charge electrophoresis (ICEP) driven metallic Janus microrobots. A direct current (DC) magnetic field applied in the direction perpendicular to the electric field maintains the linear movement of particles in a 2D plane. Phoretic force spectroscopy (PFS), a phase-sensitive detection method to detect the motions of phoretic particles, is used to characterize the frequency-dependent phoretic mobility and drag coefficient of the phoretic force. When the electric field is scanned over a frequency range of 1 kHz-1 MHz, the Janus particles exhibit an ICEP direction reversal at a crossover frequency at ~30 kH., Below this crossover frequency, the particle moves in a direction towards the dielectric side of the particle, and above this frequency, the particle moves towards the metallic side. The ICEP phoretic drag coefficient measured by PFS is found to be similar to that of the Stokes drag. Further investigation is required to study microscopic interpretations of the frequency at which ICEP mobility switched signs and the reason why the magnitudes of the forward and reversed modes of ICEP are so different.
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Affiliation(s)
- Chong Shen
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - Zhiyu Jiang
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - Lanfang Li
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
| | - James F. Gilchrist
- Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA;
| | - H. Daniel Ou-Yang
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA; (C.S.); (Z.J.); (L.L.)
- Emulsion Polymers Institute, Lehigh University, Bethlehem, PA 18015, USA
- Department of Bioengineering, Lehigh University, Bethlehem, PA 18015, USA
- Correspondence:
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Paul A, Mukherjee S, Dhar J, Ghosal S, Chakraborty S. The effect of the finite size of ions and Debye layer overspill on the screened Coulomb interactions between charged flat plates. Electrophoresis 2019; 41:607-614. [PMID: 31855289 DOI: 10.1002/elps.201900318] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/21/2019] [Accepted: 12/14/2019] [Indexed: 11/08/2022]
Abstract
Screened repulsion between uniformly charged plates with an intervening electrolyte is analyzed for strongly overlapped electrical double layers (EDL), accounting for the steric effect of ions and their expulsion from EDL edges into the surrounding solution. As a generalization of a study by Philipse et al. which does not account for these effects, an analytical expression is derived for the repulsion pressure in the limit of infinitely long plates with a zero-field assumption, which agrees closely with the corresponding numerical solution at low inter-plate separations. Our results show an augmented repulsive pressure for finite-sized ions at strong EDL overlaps. For plates with a finite lateral size, we demonstrate a further extended domain of low inter-plate gaps where the repulsion pressure increases with ion size due to a strong interplay between the steric interaction of ions and the EDL overspill phenomenon, considered earlier in a study by Ghosal & Sherwood limited to the linear Debye-Hückel regime (which cannot account for the steric effect of ions). This investigation on a simple model should enhance our understanding of the interaction between charged particles in electrophoresis, nanoscale self-assembly, active particles, and various other electrokinetic systems.
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Affiliation(s)
- Arghyadeep Paul
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Siddhartha Mukherjee
- Advanced Technology Development Center, Indian Institute of Technology Kharagpur, Kharagpur, India
| | | | - Sandip Ghosal
- Department of Mechanical Engineering & Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois, USA
| | - Suman Chakraborty
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India.,Advanced Technology Development Center, Indian Institute of Technology Kharagpur, Kharagpur, India
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10
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Salari A, Navi M, Lijnse T, Dalton C. AC Electrothermal Effect in Microfluidics: A Review. MICROMACHINES 2019; 10:E762. [PMID: 31717932 PMCID: PMC6915365 DOI: 10.3390/mi10110762] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 10/27/2019] [Accepted: 10/28/2019] [Indexed: 02/06/2023]
Abstract
The electrothermal effect has been investigated extensively in microfluidics since the 1990s and has been suggested as a promising technique for fluid manipulations in lab-on-a-chip devices. The purpose of this article is to provide a timely overview of the previous works conducted in the AC electrothermal field to provide a comprehensive reference for researchers new to this field. First, electrokinetic phenomena are briefly introduced to show where the electrothermal effect stands, comparatively, versus other mechanisms. Then, recent advances in the electrothermal field are reviewed from different aspects and categorized to provide a better insight into the current state of the literature. Results and achievements of different studies are compared, and recommendations are made to help researchers weigh their options and decide on proper configuration and parameters.
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Affiliation(s)
- Alinaghi Salari
- Biomedical Engineering Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada;
- Institute for Biomedical Engineering, Science and Technology (iBEST), St. Michael’s Hospital, Toronto, ON M5B 1T8, Canada
- Keenan Research Centre, St. Michael’s Hospital, Toronto, ON M5B 1T8, Canada
| | - Maryam Navi
- Biomedical Engineering Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada;
- Institute for Biomedical Engineering, Science and Technology (iBEST), St. Michael’s Hospital, Toronto, ON M5B 1T8, Canada
- Keenan Research Centre, St. Michael’s Hospital, Toronto, ON M5B 1T8, Canada
| | - Thomas Lijnse
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB T2N 1N4, Canada;
| | - Colin Dalton
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB T2N 1N4, Canada;
- Electrical and Computer Engineering Department, University of Calgary, Calgary, AB T2N 1N4, Canada
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11
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Jimenez E, Escandón J, Méndez F, Bautista O. Combined viscoelectric and steric effects on the electroosmotic flow in nano/microchannels with heterogeneous zeta potentials. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.05.050] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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12
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Mitra S, Mukherjee S, Ghosh A, Bandyopadhyay D. Effects of Fluid–Structure–Interaction and Surface Heterogeneity on the Electrophoresis of Microparticles. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.8b06345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Shirsendu Mitra
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Shreya Mukherjee
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Abir Ghosh
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Dipankar Bandyopadhyay
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
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Kumar B, Gopmandal PP, Sinha RK, Ohshima H. Electrophoresis of hydrophilic/hydrophobic rigid colloid with effects of relaxation and ion size. Electrophoresis 2019; 40:1282-1292. [DOI: 10.1002/elps.201800427] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/04/2019] [Accepted: 01/24/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Binod Kumar
- Department of MathematicsNational Institute of Technology PatnaPatna India
| | - Partha P. Gopmandal
- Department of MathematicsNational Institute of Technology PatnaPatna India
- Department of MathematicsNational Institute of Technology DurgapurDurgapur India
| | - R. K. Sinha
- Department of MathematicsNational Institute of Technology PatnaPatna India
| | - H. Ohshima
- Faculty of Pharmaceutical SciencesTokyo University of ScienceNoda Chiba Japan
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López-García JJ, Horno J, Grosse C. Numerical Solution of the Electrokinetic Equations for Multi-ionic Electrolytes Including Different Ionic Size Related Effects. MICROMACHINES 2018; 9:mi9120647. [PMID: 30544513 PMCID: PMC6316493 DOI: 10.3390/mi9120647] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 11/26/2018] [Accepted: 12/05/2018] [Indexed: 11/16/2022]
Abstract
One of the main assumptions of the standard electrokinetic model is that ions behave as point-like entities. In a previous work (López-García, et al., 2015) we removed this assumption and analyzed the influence of finite ionic size on the dielectric and electrokinetic properties of colloidal suspensions using both the Bikerman and the Carnahan⁻Starling equations for the steric interactions. It was shown that these interactions improved upon the standard model predictions so that the surface potential, electrophoretic mobility, and the conductivity and permittivity increment values were increased. In the present study, we extend our preceding works to systems made of three or more ionic species with different ionic sizes. Under these conditions, the Bikerman and Carnahan⁻Starling expressions cease to be valid since they were deduced for single-size spheres. Fortunately, the Carnahan⁻Starling expression has been extended to mixtures of spheres of unequal size, namely the "Boublik⁻Mansoori⁻Carnahan⁻Starling⁻Leland" (BMCSL) equation of state, making it possible to analyze the most general case. It is shown that the BMCSL expression leads to results that differ qualitatively and quantitatively from the standard electrokinetic model.
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Affiliation(s)
- José J López-García
- Departamento de Física, Universidad de Jaén, Campus Las Lagunillas, Ed. A-3, 23071 Jaén, Spain.
| | - José Horno
- Departamento de Física, Universidad de Jaén, Campus Las Lagunillas, Ed. A-3, 23071 Jaén, Spain.
| | - Constantino Grosse
- Departamento de Física, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán, Argentina.
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Hossan MR, Dutta D, Islam N, Dutta P. Review: Electric field driven pumping in microfluidic device. Electrophoresis 2018; 39:702-731. [PMID: 29130508 PMCID: PMC5832652 DOI: 10.1002/elps.201700375] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/31/2017] [Accepted: 11/01/2017] [Indexed: 01/05/2023]
Abstract
Pumping of fluids with precise control is one of the key components in a microfluidic device. The electric field has been used as one of the most popular and efficient nonmechanical pumping mechanism to transport fluids in microchannels from the very early stage of microfluidic technology development. This review presents fundamental physics and theories of the different microscale phenomena that arise due to the application of an electric field in fluids, which can be applied for pumping of fluids in microdevices. Specific mechanisms considered in this report are electroosmosis, AC electroosmosis, AC electrothermal, induced charge electroosmosis, traveling wave dielectrophoresis, and liquid dielectrophoresis. Each phenomenon is discussed systematically with theoretical rigor and role of relevant key parameters are identified for pumping in microdevices. We specifically discussed the electric field driven body force term for each phenomenon using generalized Maxwell stress tensor as well as simplified effective dipole moment based method. Both experimental and theoretical works by several researchers are highlighted in this article for each electric field driven pumping mechanism. The detailed understanding of these phenomena and relevant key parameters are critical for better utilization, modulation, and selection of appropriate phenomenon for efficient pumping in a specific microfluidic application.
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Affiliation(s)
- Mohammad R. Hossan
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Diganta Dutta
- Department of Physics, University of Nebraska, Kearney, NE 68849, USA
| | - Nazmul Islam
- Department of Electrical Engineering, University of Texas Rio Grande Valley, TX, USA
| | - Prashanta Dutta
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA
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16
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Zhao W, Liu X, Yang F, Wang K, Bai J, Qiao R, Wang G. Study of Oscillating Electroosmotic Flows with High Temporal and Spatial Resolution. Anal Chem 2018; 90:1652-1659. [PMID: 29256244 DOI: 10.1021/acs.analchem.7b02985] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Near-wall velocity of oscillating electroosmotic flow (OEOF) driven by an AC electric field has been investigated using a laser-induced fluorescence photobleaching anemometer (LIFPA). For the first time, an up to 3 kHz velocity response of OEOF has been successfully measured experimentally, even though the oscillating velocity is as low as 600 nm/s. It is found that the oscillating velocity decays with the forcing frequency ff as ff-0.66. In the investigated range of electric field intensity (EA), below 1 kHz, the linear relation between oscillating velocity and EA is also observed. Because the oscillating velocity at high frequency is very small, the contribution of noise to velocity measurement is significant, and it is discussed in this manuscript. The investigation reveals the instantaneous response of OEOF to the temporal change of electric fields, which exists in almost all AC electrokinetic flows. Furthermore, the experimental observations are important for designing OEOF-based micro/nanofluidics systems.
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Affiliation(s)
- Wei Zhao
- Institute of Photonics and Photon-technology, International Scientific and Technological Cooperation Base of Photoelectric Technology and Functional Materials and Application, Northwest University , 229 North Taibai Road, Xi'an 710069, People's Republic of China.,Department of Mechanical Engineering & Biomedical Engineering Program, University of South Carolina , Columbia, South Carolina 29208, United States
| | - Xin Liu
- Department of Mechanical Engineering & Biomedical Engineering Program, University of South Carolina , Columbia, South Carolina 29208, United States
| | - Fang Yang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University , Changchun 130012, People's Republic of China
| | - Kaige Wang
- Institute of Photonics and Photon-technology, International Scientific and Technological Cooperation Base of Photoelectric Technology and Functional Materials and Application, Northwest University , 229 North Taibai Road, Xi'an 710069, People's Republic of China
| | - Jintao Bai
- Institute of Photonics and Photon-technology, International Scientific and Technological Cooperation Base of Photoelectric Technology and Functional Materials and Application, Northwest University , 229 North Taibai Road, Xi'an 710069, People's Republic of China
| | - Rui Qiao
- Department of Mechanical Engineering, Virginia Tech , Blacksburg, Virginia 24061, United States
| | - Guiren Wang
- Department of Mechanical Engineering & Biomedical Engineering Program, University of South Carolina , Columbia, South Carolina 29208, United States
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17
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Combined viscoelectric and steric effects on the electroosmotic flow in a microchannel under induced high zeta potentials. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.04.081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Liu W, Ren Y, Tao Y, Yao B, Li Y. Simulation analysis of rectifying microfluidic mixing with field-effect-tunable electrothermal induced flow. Electrophoresis 2017; 39:779-793. [DOI: 10.1002/elps.201700234] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/20/2017] [Accepted: 08/28/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Weiyu Liu
- School of Electronics and Control Engineering; Chang'an University; Xi'an P. R. China
| | - Yukun Ren
- School of Mechatronics Engineering; Harbin Institute of Technology; Harbin P. R. China
- State Key Laboratory of Robotics and System; Harbin Institute of Technology; Harbin P. R. China
| | - Ye Tao
- School of Mechatronics Engineering; Harbin Institute of Technology; Harbin P. R. China
| | - Bobin Yao
- School of Electronics and Control Engineering; Chang'an University; Xi'an P. R. China
| | - You Li
- School of Electronics and Control Engineering; Chang'an University; Xi'an P. R. China
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19
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Kolekar SK, Dubey A, Date KS, Datar S, Gopinath CS. An attempt to correlate surface physics with chemical properties: molecular beam and Kelvin probe investigations of Ce 1-xZr xO 2 thin films. Phys Chem Chem Phys 2016; 18:27594-27602. [PMID: 27711510 DOI: 10.1039/c6cp04700a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
What is the correlation between physical properties of the surfaces (such as surface potential, electronic nature of the surface), and chemical and catalysis properties (such as chemisorption, sticking probability of surface)? An attempt has been made to explore any correlation that might exist between the physical and chemical properties of thin film surfaces. Kelvin probe microscopy (KPM) and the molecular beam (MB) methods were employed to carry out the surface potential, and oxygen adsorption and oxygen storage capacity (OSC) measurements on Ce1-xZrxO2 thin films. A sol-gel synthesis procedure and spin-coating deposition method have been applied to make continuous nanocrystalline Ce1-xZrxO2 (x = 0-1) (CZ) thin films with uniform thickness (35-50 nm); however, surface roughness and porosity inherently changes with CZ composition. MB studies of O2 adsorption on CZ reveal high OSC for Ce0.9Zr0.1O2, which also exhibits highly porous and significantly rough surface characteristics. The surface potential observed from KPM studies varied between 30 and 80 mV, with Ce-rich compositions exhibiting the highest surface potential. Surface potential shows large changes after reduction or oxidation of the CZ film demonstrating the influence of Ce3+/Ce4+ on surface potential, which is also a key to catalytic activity for ceria-based catalysts. The surface potential measured from KPM and the OSC measured from MB vary linearly and they depend on the Ce3+/Ce4+ ratio. More and detailed studies are suggested to arrive at a correlation between the physical and chemical properties of the surfaces.
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Affiliation(s)
- Sadhu K Kolekar
- Catalysis Division, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India. and Center of Excellence on Surface Science, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India
| | - Anjani Dubey
- Catalysis Division, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India. and Center of Excellence on Surface Science, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India
| | - Kalyani S Date
- Department of Applied Physics, Defence Institute of Advanced Technology, Pune 411025, India
| | - Suwarna Datar
- Department of Applied Physics, Defence Institute of Advanced Technology, Pune 411025, India
| | - Chinnakonda S Gopinath
- Catalysis Division, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India. and Center of Excellence on Surface Science, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India
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20
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Boymelgreen A, Yossifon G, Miloh T. Propulsion of Active Colloids by Self-Induced Field Gradients. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9540-7. [PMID: 27611819 DOI: 10.1021/acs.langmuir.6b01758] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Previously, metallodielectric Janus particles have been shown to travel with their dielectric hemisphere forward under low frequency applied electric fields as a result of asymmetric induced-charge electroosmotic flow. Here, it is demonstrated that at high frequencies, well beyond the charge relaxation time of the electric double layer induced around the particle, rather than the velocity decaying to zero, the Janus particles reverse direction, traveling with their metallic hemisphere forward. It is proposed that such motion is the result of a surface force, arising from localized nonuniform electric field gradients, induced by the dual symmetry-breaking of an asymmetric particle adjacent to a wall, which act on the induced dipole of the particle to drive net motion even in a uniform AC field. Although the field is external, since the driving gradient is induced on the particle level, it may be considered an active colloid. We have thus termed this propulsion mechanism "self-dielectrophoresis", to distinguish from traditional dielectrophoresis where the driving nonuniform field is externally fixed and the particle direction is restricted. It is demonstrated theoretically and experimentally that the critical frequency at which the particle reverses direction can be characterized by a nondimensional parameter which is a function of electrolyte concentration and particle size.
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Affiliation(s)
- Alicia Boymelgreen
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion - Israel Institute of Technology , Haifa 32000, Israel
| | - Gilad Yossifon
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion - Israel Institute of Technology , Haifa 32000, Israel
| | - Touvia Miloh
- School of Mechanical Engineering, University of Tel-Aviv , Tel-Aviv 69978, Israel
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21
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Sugioka H. Direct simulation of phase delay effects on induced-charge electro-osmosis under large ac electric fields. Phys Rev E 2016; 94:022609. [PMID: 27627362 DOI: 10.1103/physreve.94.022609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Indexed: 06/06/2023]
Abstract
The standard theory of induced-charge electro-osmosis (ICEO) often overpredicts experimental values of ICEO velocities. Using a nonsteady direct multiphysics simulation technique based on the coupled Poisson-Nernst-Planck and Stokes equations for an electrolyte around a conductive cylinder subject to an ac electric field, we find that a phase delay effect concerning an ion response provides a fundamental mechanism for electrokinetic suppression. A surprising aspect of our findings is that the phase delay effect occurs even at much lower frequencies (e.g., 50 Hz) than the generally believed charging frequency of an electric double layer (typically, 1 kHz) and it can decrease the electrokinetic velocities in one to several orders. In addition, we find that the phase delay effect may also cause a change in the electrokinetic flow directions (i.e., flow reversal) depending on the geometrical conditions. We believe that our findings move toward a more complete understanding of complex experimental nonlinear electrokinetic phenomena.
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Affiliation(s)
- Hideyuki Sugioka
- Frontier Research Center, Canon Inc., 30-2, Shimomaruko 3-chome, Ohta-ku, Tokyo 146-8501, Japan and Department of Mechanical Systems Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
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22
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Oh JM, Kang IS. Ion size effects on the osmotic pressure and electrocapillarity in a nanoslit: Symmetric and asymmetric ion sizes. Phys Rev E 2016; 93:063112. [PMID: 27415363 DOI: 10.1103/physreve.93.063112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 06/06/2023]
Abstract
We analyze the effect of asymmetric finite ion size in nanoconfinement in the view of osmotic pressure and electrocapillarity. When the confinement width becomes comparable with the Debye length, the overlapped electric double layer is significantly deformed by the steric effects. We derive the osmotic pressure from the modified Poisson-Boltzmann equation in a nanoslit to examine the deviation from the ideal osmotic pressure and the repulsive force on the wall considering the asymmetry of ion sizes. Then the electrocapillarity due to the steric effect is investigated under constant potential condition with the flat interface assumption. Later, the deformation by the electrocapillarity is also considered in the first order approximation.
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Affiliation(s)
- J M Oh
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), 50 UNIST-gil, Ulju-gun 44919, Republic of Korea
| | - I S Kang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, Republic of Korea
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23
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Minton G, Lue L. The influence of excluded volume and excess ion polarisability on the capacitance of the electric double layer. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1169327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Geraint Minton
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow, UK
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24
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Strategies on improving the micro-fluidic devices using the nonlinear electro- and thermo-kinetic phenomena. Adv Colloid Interface Sci 2015; 226:44-53. [PMID: 26482087 DOI: 10.1016/j.cis.2015.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 07/03/2015] [Accepted: 07/29/2015] [Indexed: 11/21/2022]
Abstract
Surface science is key to innovations on microfluidics, smart materials, and future non-equilibrium systems. However, challenging issues still exist in this field. In this article, from the viewpoint of the fundamental design, we will briefly review our strategies on improving the micro-fluidic devices using the nonlinear electro- and thermo-kinetic phenomena. In particular, we will review the microfluidic applications using ICEO, the correction based on the ion-conserving Poisson-Boltzmann theory, the direct simulation on ICEO, and the new horizon such as nonlinear thermo-kinetic phenomena and the artificial cilia.
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25
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Influence of steric interactions on the dielectric and electrokinetic properties in colloidal suspensions. J Colloid Interface Sci 2015; 458:273-83. [DOI: 10.1016/j.jcis.2015.07.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/24/2015] [Accepted: 07/25/2015] [Indexed: 11/18/2022]
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26
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Electrokinetic mixing at high zeta potentials: Ionic size effects on cross stream diffusion. J Colloid Interface Sci 2015; 442:8-14. [DOI: 10.1016/j.jcis.2014.11.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/20/2014] [Accepted: 11/21/2014] [Indexed: 11/19/2022]
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27
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Collins L, Jesse S, Kilpatrick JI, Tselev A, Okatan MB, Kalinin SV, Rodriguez BJ. Kelvin probe force microscopy in liquid using electrochemical force microscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:201-14. [PMID: 25671164 PMCID: PMC4311590 DOI: 10.3762/bjnano.6.19] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/10/2014] [Indexed: 05/24/2023]
Abstract
Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid-gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid-liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe-sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid-liquid interface.
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Affiliation(s)
- Liam Collins
- School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stephen Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jason I Kilpatrick
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Alexander Tselev
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Baris Okatan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sergei V Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Brian J Rodriguez
- School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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28
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Hoshyargar V, Ashrafizadeh SN, Sadeghi A. Drastic alteration of diffusioosmosis due to steric effects. Phys Chem Chem Phys 2015; 17:29193-200. [DOI: 10.1039/c5cp05327g] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We demonstrate essential quantitative and qualitative distinctions between the steric effects on classical electrokinetic phenomena like electroosmosis and on diffusioosmosis.
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Affiliation(s)
- Vahid Hoshyargar
- Research Lab for Advanced Separation Processes
- Department of Chemical Engineering
- Iran University of Science and Technology
- Tehran 16846-13114
- Iran
| | - Seyed Nezameddin Ashrafizadeh
- Research Lab for Advanced Separation Processes
- Department of Chemical Engineering
- Iran University of Science and Technology
- Tehran 16846-13114
- Iran
| | - Arman Sadeghi
- Department of Mechanical Engineering
- University of Kurdistan
- Sanandaj 66177-15175
- Iran
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29
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Das S, Chanda S, Eijkel JCT, Tas NR, Chakraborty S, Mitra SK. Filling of charged cylindrical capillaries. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:043011. [PMID: 25375597 DOI: 10.1103/physreve.90.043011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Indexed: 06/04/2023]
Abstract
We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because of decreased velocity gradients at the wall. Both these effects essentially stem from the spontaneous formation of an electric double layer (EDL) and the resulting streaming potential caused by the net capillary-flow-driven advection of ionic species within the EDL. Our results demonstrate that filling of charged capillaries also exhibits the well-known linear and Washburn regimes witnessed for uncharged capillaries, although the filling rate is always lower than that of the uncharged capillary. We attribute this to a competitive success of the lowering of the driving forces (because of electroviscous effects), in comparison to the effect of weaker drag forces. We further reveal that the time at which the transition between the linear and the Washburn regime occurs may become significantly altered with the introduction of surface charges, thereby altering the resultant capillary dynamics in a rather intricate manner.
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Affiliation(s)
- Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Sourayon Chanda
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G8
| | - J C T Eijkel
- BIOS, The Lab-on-a-Chip Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - N R Tas
- Transducers Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Suman Chakraborty
- Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur-721302, India
| | - Sushanta K Mitra
- Department of Mechanical Engineering, Lassonde School of Engineering, York University, Toronto, Ontario, Canada M3J1P3
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30
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Xu Z, Ma M, Liu P. Self-energy-modified Poisson-Nernst-Planck equations: WKB approximation and finite-difference approaches. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:013307. [PMID: 25122410 DOI: 10.1103/physreve.90.013307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Indexed: 06/03/2023]
Abstract
We propose a modified Poisson-Nernst-Planck (PNP) model to investigate charge transport in electrolytes of inhomogeneous dielectric environment. The model includes the ionic polarization due to the dielectric inhomogeneity and the ion-ion correlation. This is achieved by the self energy of test ions through solving a generalized Debye-Hückel (DH) equation. We develop numerical methods for the system composed of the PNP and DH equations. Particularly, toward the numerical challenge of solving the high-dimensional DH equation, we developed an analytical WKB approximation and a numerical approach based on the selective inversion of sparse matrices. The model and numerical methods are validated by simulating the charge diffusion in electrolytes between two electrodes, for which effects of dielectrics and correlation are investigated by comparing the results with the prediction by the classical PNP theory. We find that, at the length scale of the interface separation comparable to the Bjerrum length, the results of the modified equations are significantly different from the classical PNP predictions mostly due to the dielectric effect. It is also shown that when the ion self energy is in weak or mediate strength, the WKB approximation presents a high accuracy, compared to precise finite-difference results.
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Affiliation(s)
- Zhenli Xu
- Department of Mathematics, Institute of Natural Sciences, and MoE Key Lab of Scientific and Engineering Computing, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Manman Ma
- Department of Mathematics, Institute of Natural Sciences, and MoE Key Lab of Scientific and Engineering Computing, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Pei Liu
- Department of Mathematics, Institute of Natural Sciences, and MoE Key Lab of Scientific and Engineering Computing, Shanghai Jiao Tong University, Shanghai 200240, China
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31
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Davidson SM, Andersen MB, Mani A. Chaotic induced-charge electro-osmosis. PHYSICAL REVIEW LETTERS 2014; 112:128302. [PMID: 24724683 DOI: 10.1103/physrevlett.112.128302] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Indexed: 05/11/2023]
Abstract
We present direct numerical simulations of the coupled Poisson-Nernst-Planck and Navier-Stokes equations for an electrolyte around a polarizable cylinder subject to an external electric field. For high fields, a novel chaotic flow phenomenon is discovered. Our calculations indicate significant improvement in the prediction of the mean flow relative to standard asymptotic models. These results open possibilities for chaos-enhanced mixing in microdevices and provide insight into barriers to efficient electrokinetic micropumps with broad applications in electrochemical and lab-on-a-chip systems.
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Affiliation(s)
- Scott M Davidson
- Center for Turbulence Research, Stanford University, Stanford, California 94305, USA and Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Mathias B Andersen
- Center for Turbulence Research, Stanford University, Stanford, California 94305, USA and Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
| | - Ali Mani
- Center for Turbulence Research, Stanford University, Stanford, California 94305, USA and Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
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32
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Zhao C, Yang C. Electrokinetics of non-Newtonian fluids: a review. Adv Colloid Interface Sci 2013; 201-202:94-108. [PMID: 24148843 DOI: 10.1016/j.cis.2013.09.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 08/19/2013] [Accepted: 09/16/2013] [Indexed: 10/26/2022]
Abstract
This work presents a comprehensive review of electrokinetics pertaining to non-Newtonian fluids. The topic covers a broad range of non-Newtonian effects in electrokinetics, including electroosmosis of non-Newtonian fluids, electrophoresis of particles in non-Newtonian fluids, streaming potential effect of non-Newtonian fluids and other related non-Newtonian effects in electrokinetics. Generally, the coupling between non-Newtonian hydrodynamics and electrostatics not only complicates the electrokinetics but also causes the fluid/particle velocity to be nonlinearly dependent on the strength of external electric field and/or the zeta potential. Shear-thinning nature of liquids tends to enhance electrokinetic phenomena, while shear-thickening nature of liquids leads to the reduction of electrokinetic effects. In addition, directions for the future studies are suggested and several theoretical issues in non-Newtonian electrokinetics are highlighted.
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33
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Das S, Guha A, Mitra SK. Exploring new scaling regimes for streaming potential and electroviscous effects in a nanocapillary with overlapping electric double layers. Anal Chim Acta 2013; 804:159-66. [PMID: 24267077 DOI: 10.1016/j.aca.2013.09.061] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 09/04/2013] [Accepted: 09/28/2013] [Indexed: 10/26/2022]
Abstract
In this paper, we unravel new scaling regimes for streaming potential and electroviscous effects in a nanocapillary with thick overlapping Electric Double Layers (EDLs). We observe that the streaming potential, for a given value of the capillary zeta (ζ) potential, varies with the EDL thickness and a dimensionless parameter R, quantifying the conduction current. Depending on the value of R, variation of the streaming potential with the EDL thickness demonstrates distinct scaling regimes: one can witness a Quadratic Regime where the streaming potential varies as the square of the EDL thickness, a Weak Regime where the streaming potential shows a weaker variation with the EDL thickness, and a Saturation Regime where the streaming potential ceases to vary with the EDL thickness. Effective viscosity, characterizing the electroviscous effect, obeys the variation of the streaming potential for smaller EDL thickness values; however, for larger EDL thickness the electroosmotic flow profile dictates the electroviscous effect, with insignificant contribution of the streaming potential.
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Affiliation(s)
- Siddhartha Das
- Micro and Nanoscale Transport Laboratory, Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G8
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Zhao H, Zhai S. The Influence of Dielectric Decrement on Electrokinetics. JOURNAL OF FLUID MECHANICS 2013; 724:69-94. [PMID: 24910471 PMCID: PMC4048037 DOI: 10.1017/jfm.2013.152] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We treat the dielectric decrement induced by excess ion polarization as a source of ion specificity and explore its impact on electrokinetics. We employ a modified Poisson-Nernst-Planck (PNP) equations accounting for the dielectric decrement. The dielectric decrement is determined by the excess ion polarization parameter α and when α = 0 the standard PNP model is recovered. Our model shows that ions saturate at large zeta potentials (ζ). Because of ion saturation, a condensed counterion layer forms adjacent to the charged surface, introducing a new length scale, the thickness of the condensed layer (lc ). For the electro-osmotic mobility, the dielectric decrement weakens the electro-osmotic flow owing to the decrease of the dielectric permittivity. At large ζ, when α ≠ 0, the electro-osmotic mobility is found to be proportional to ζ/2, in contrast to ζ predicted by the standard PNP model. This is attributed to ion saturation at large ζ. In terms of the electrophoretic mobility Me , we carry out both an asymptotic analysis in the thin-double-layer limit and solve the full modified PNP model to compute Me . Our analysis reveals that the impact of the dielectric decrement is intriguing. At small and moderate ζ, the dielectric decrement decreases Me with an increasing α. At large ζ, it is well known that the surface conduction becomes significant and plays an important role in determining Me . It is observed that the dielectric decrement effectively reduces the surface conduction. Hence in stark contrast, Me increases as α increases. Our predictions of the contrast dependence of the mobility on α at different zeta potentials qualitatively agree with experimental results on the dependence of the mobility among ions and provide a possible explanation for such ion specificity. Finally, the comparisons between the thin-double-layer asymptotic analysis and the full simulations of the modified PNP model suggest that at large ζ the validity of the thin-double-layer approximation is determined by lc rather than the traditional Debye length.
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Affiliation(s)
- Hui Zhao
- All correspondence should be directed to this author ()
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Lazo I, Lavrentovich OD. Liquid-crystal-enabled electrophoresis of spheres in a nematic medium with negative dielectric anisotropy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120255. [PMID: 23459958 DOI: 10.1098/rsta.2012.0255] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We describe electrophoresis of spherical dielectric particles in a uniformly aligned nematic medium with a negative dielectric anisotropy. A spherical particle that orients the liquid crystal (LC) perpendicularly to its surface moves under the application of a uniform direct current or alternating current electric field. The electric field causes no distortions of the LC director far away from the sphere. Electrophoresis in the nematic LC shows two types of nonlinearity in the velocity versus field dependence. The velocity component parallel to the applied electric field grows linearly with the field, but when the field is high enough, it also shows a cubic dependence. The most interesting is the second type of nonlinear electrophoresis that causes the sphere to move perpendicularly to the applied field. This perpendicular component of velocity is proportional to the square of the field. The effect exists only in an LC and disappears when the material is melted into an isotropic fluid. The quadratic effect is caused by the dipolar symmetry of director distortions around the sphere and is classified as an LC-enabled electrophoresis (LCEEP). The nonlinear electrophoretic mobility of particles in LCEEP offers a rich variety of control parameters to design three-dimensional trajectories of particles for microfluidic and optofluidic applications.
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Affiliation(s)
- Israel Lazo
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA
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36
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Suh YK, Baek KH. Competition between the bulk and the dissociation layer in electrohydrodynamic flow of dielectric liquid around coplanar electrodes. Phys Rev E 2013; 87:023009. [PMID: 23496612 DOI: 10.1103/physreve.87.023009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/04/2012] [Indexed: 11/07/2022]
Abstract
An experimental and numerical study has been conducted on the electrohydrodynamic flow around coplanar electrodes with a dielectric liquid: dodecane mixed with the surfactant Span 80. It is shown that the flow is asymmetric, although the electrode is symmetrically arranged, and numerically, we have shown that a difference in the ionic size can reproduce such asymmetric patterns. It is also found that the dissociation layer effect becomes more important in determining the flow pattern than is predicted from the conventional theory where the Langevin formula is used for the recombination constant. In numerical simulations, reducing the recombination constant to 0.035-0.055 times the Langevin value turned out to produce good comparisons between the experimental and the numerical results for the electrode pairs with 1 and 0.2 mm gaps.
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Affiliation(s)
- Y K Suh
- Department of Mechanical Engineering, Dong-A University, 840 Hadan-dong, Saha-gu, Busan 604-714, Korea
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37
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Zhao H. Influence of nonelectrostatic ion-ion interactions on double-layer capacitance. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:051502. [PMID: 23214784 DOI: 10.1103/physreve.86.051502] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Indexed: 06/01/2023]
Abstract
Recently a Poisson-Helmholtz-Boltzmann (PHB) model [Bohinc et al., Phys. Rev. E 85, 031130 (2012)] was developed by accounting for solvent-mediated nonelectrostatic ion-ion interactions. Nonelectrostatic interactions are described by a Yukawa-like pair potential. In the present work, we modify the PHB model by adding steric effects (finite ion size) into the free energy to derive governing equations. The modified PHB model is capable of capturing both ion specificity and ion crowding. This modified model is then employed to study the capacitance of the double layer. More specifically, we focus on the influence of nonelectrostatic ion-ion interactions on charging a double layer near a flat surface in the presence of steric effects. We numerically compute the differential capacitance as a function of the voltage under various conditions. At small voltages and low salt concentrations (dilute solution), we find out that the predictions from the modified PHB model are the same as those from the classical Poisson-Boltzmann theory, indicating that nonelectrostatic ion-ion interactions and steric effects are negligible. At moderate voltages, nonelectrostatic ion-ion interactions play an important role in determining the differential capacitance. Generally speaking, nonelectrostatic interactions decrease the capacitance because of additional nonelectrostatic repulsion among excess counterions inside the double layer. However, increasing the voltage gradually favors steric effects, which induce a condensed layer with crowding of counterions near the electrode. Accordingly, the predictions from the modified PHB model collapse onto those computed by the modified Poisson-Boltzmann theory considering steric effects alone. Finally, theoretical predictions are compared and favorably agree with experimental data, in particular, in concentrated solutions, leading one to conclude that the modified PHB model adequately predicts the diffuse-charge dynamics of the double layer with ion specificity and steric effects.
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Affiliation(s)
- Hui Zhao
- Department of Mechanical Engineering University of Nevada, Las Vegas, Nevada 89154, USA.
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Storey BD, Bazant MZ. Effects of electrostatic correlations on electrokinetic phenomena. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:056303. [PMID: 23214872 DOI: 10.1103/physreve.86.056303] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Indexed: 05/17/2023]
Abstract
The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture subtle aspects of molecular simulations and allows for simple calculations of electrokinetic flows in correlated ionic fluids. Charge-density oscillations tend to reduce electro-osmotic flow and streaming current, and overscreening of surface charge can lead to flow reversal. These effects also help to explain the suppression of induced-charge electrokinetic phenomena at high salt concentrations.
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Affiliation(s)
- Brian D Storey
- Franklin W. Olin College of Engineering, Needham, Massachusetts 02492, USA
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Sugioka H. Ion-conserving Poisson-Boltzmann theory. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:016318. [PMID: 23005536 DOI: 10.1103/physreve.86.016318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/11/2012] [Indexed: 06/01/2023]
Abstract
It is well known that the Poisson-Nernst-Planck (PNP) theory and the classical Gouy-Chapman theory are inconsistent at a high applied voltage. For solving this problem, we propose an ion-conserving Poisson-Boltzmann theory, which shows remarkable agreement with the numerical PNP solutions, even at a high applied voltage. In other words, we have found the exact analytical solutions for steady PNP equations; we believe that this finding greatly contributes to understanding surface science between solids and liquids.
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Affiliation(s)
- Hideyuki Sugioka
- Frontier Research Center, Canon Inc., 30-2, Shimomaruko 3-chome, Tokyo 146-8501, Japan.
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Das S. Electric-double-layer potential distribution in multiple-layer immiscible electrolytes: effect of finite ion sizes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:012502. [PMID: 22400605 DOI: 10.1103/physreve.85.012502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 12/06/2011] [Indexed: 05/31/2023]
Abstract
In a recent study [S. Das and S. Hardt, Phys. Rev. E 84, 022502 (2011).], we provided analytical results for the electric-double-layer (EDL) electrostatic potential distribution in a system of immiscible electrolyte layers confined between plates with gap dimensions comparable to the EDL thickness. We demonstrated that the intrinsic jumps in the ion-solvent interactions across the interface of the immiscible electrolytes lead to nontrivial electrostatic potential distributions that may completely defy or substantially augment the effect of the boundary wall potential. In this Brief Report, I extend this calculation to obtain analytical and numerical results for the case with finite ion sizes (or a finite ionic steric effect). It is found that the finite steric effect substantially enhances the contributions of jump in the ion-solvent interactions in the overall electrostatic potential distribution. More importantly, I demonstrate that such jumps in the ion-solvent interactions, owing to the immiscibility of the electrolytes, ensure that even for very weak wall zeta potentials, the steric effect can significantly affect the electrostatic potential distribution.
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Affiliation(s)
- Siddhartha Das
- Physics of Fluids Group and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, NL-7500 AE Enschede, The Netherlands
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41
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Ng WY, Ramos A, Lam YC, Wijaya IPM, Rodriguez I. DC-biased AC-electrokinetics: a conductivity gradient driven fluid flow. LAB ON A CHIP 2011; 11:4241-7. [PMID: 22052533 DOI: 10.1039/c1lc20495e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
This paper studies the principles of fluid flow manipulation based on DC-biased AC-electrokinetics. This method makes use of planar parallel electrodes in a microfluidic channel in contact with an electrolyte solution, with a DC biased AC electrical signal applied to the electrode pair. Due to the application of DC bias, incipient Faradaic electrolytic reactions take place resulting in an increase of the ionic content of the bulk solution. The ionic content was found to be dissimilar at the cathodic and anodic sides of the channel and a conductivity difference of approximately 10% was measured for 2 V(DC). Fluid flow is generated by the action of the DC biased AC electric signal acting on the transverse conductivity gradient generated across the microchannel. The induced flow in the form of vortex was characterized experimentally and the results substantiated theoretically. The velocity of the induced flow vortex under the employed experimental conditions was ~600 to 700 μm s(-1) which is faster than those obtained in conventional AC-electroosmosis and AC-electrothermal types of flows.
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Affiliation(s)
- Wee Yang Ng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore, 117602, Singapore
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Xu Z, Cai W. Fast Analytical Methods for Macroscopic Electrostatic Models in Biomolecular Simulations. SIAM REVIEW. SOCIETY FOR INDUSTRIAL AND APPLIED MATHEMATICS 2011; 53:683-720. [PMID: 23745011 PMCID: PMC3671632 DOI: 10.1137/090774288] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We review recent developments of fast analytical methods for macroscopic electrostatic calculations in biological applications, including the Poisson-Boltzmann (PB) and the generalized Born models for electrostatic solvation energy. The focus is on analytical approaches for hybrid solvation models, especially the image charge method for a spherical cavity, and also the generalized Born theory as an approximation to the PB model. This review places much emphasis on the mathematical details behind these methods.
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Affiliation(s)
- Zhenli Xu
- Department of Mathematics and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China, and Department of Mathematics and Statistics, University of North Carolina, Charlotte, NC 28223 ()
| | - Wei Cai
- Department of Mathematics and Statistics, University of North Carolina, Charlotte, NC 28223 (), and Beijing International Center for Mathematical Research, Beijing, People's Republic of China, 100871
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Kim BJ, Lee SH, Rezazadeh S, Sung HJ. Simulation of an ac electro-osmotic pump with step microelectrodes. Phys Rev E 2011; 83:056302. [PMID: 21728642 DOI: 10.1103/physreve.83.056302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 03/28/2011] [Indexed: 11/07/2022]
Abstract
Pumps with step microelectrodes subjected to an ac voltage are known to have faster pumping rates than those with planar asymmetric microelectrodes. The driving force for pumping in these systems is ac electro-osmosis. This paper aims to understand the flow behaviors of pumps with step microelectrodes by using a realistic model applicable to high external voltages. This model takes the steric effect due to the finite sizes of ions into account and copes with the exponential sensitivity of the counterion concentration to voltage. The effects on the pumping flow rate of varying the pump parameters were investigated. The geometrical parameters were optimized, and the effects of varying the ac frequency and amplitude were examined. The electrical potential of the fluid and the electrical charge at the electrode surface were solved simultaneously, and the Stokes equation was used to describe the fluid flow.
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Affiliation(s)
- Byoung Jae Kim
- Department of Mechanical Engineering, KAIST, Daejeon 305-701, Korea
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Hrdlička J, Cervenka P, Přibyl M, Snita D. Zig-zag arrangement of four electrodes for ac electro-osmotic micropumps. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:016307. [PMID: 21867304 DOI: 10.1103/physreve.84.016307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Indexed: 05/31/2023]
Abstract
This paper deals with the mathematical modeling of traveling-wave ac electro-osmotic micropumps with a zig-zag arrangement of microelectrodes. A mathematical model based on the Poisson-Nernst-Planck-Navier-Stokes description is used in this study within the physically relevant ranges of the model parameters. We present an extensive set of parametrical studies concerning the dependence of the net velocity on a variety of parameters. We also demonstrate limits of the validity of the commonly used Capacitor-Resistor-Capacitor model. In order to achieve high net velocities, we found that there are the optimal values of the electrode length, the shift between the top and bottom electrode arrays, and the signal frequency. Performance of the zig-zag micropumps is evaluated by the means of back-pressure loads. The suggested zig-zag design brings two main benefits: (i) it allows an easier construction of four-phase traveling-wave micropumps without the need of spatially complicated electrode connections, and (ii) the zig-zag pumps can provide higher flow rates than those with single-sided coplanar arrangements. Another robust feature of the proposed zig-zag system is that a single flow reversal is observed at the ac frequency approximately six times higher than the reciprocal resistor-capacitor time even in low-amplitude regimes.
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Affiliation(s)
- J Hrdlička
- Department of Chemical Engineering, Institute of Chemical Technology Prague, Prague, Czech Republic
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46
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Das S, Chakraborty S. Steric-effect-induced enhancement of electrical-double-layer overlapping phenomena. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:012501. [PMID: 21867239 DOI: 10.1103/physreve.84.012501] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/18/2011] [Indexed: 05/31/2023]
Abstract
In this paper, we demonstrate that nontrivial interactions between steric effect and electrical-double-layer (EDL) overlap phenomena may augment the effective extent of EDL overlap in narrow fluidic confinements to a significant extent by virtue of rendering the channel centerline potential tending to the ζ potential in a limiting sense as the steric effect progressively intensifies. Such a behavior may result in a virtually uniform (undiminished) magnitude of the EDL potential across the entire channel height and may cause lowering of the total charge within the EDL.
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Affiliation(s)
- Siddhartha Das
- Physics of Fluids Group, JM Burgers Centre for Fluid Dynamics, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
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47
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Gillespie D, Khair AS, Bardhan JP, Pennathur S. Efficiently accounting for ion correlations in electrokinetic nanofluidic devices using density functional theory. J Colloid Interface Sci 2011; 359:520-9. [DOI: 10.1016/j.jcis.2011.03.088] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
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Sugioka H. Asymmetrical reverse vortex flow due to induced-charge electro-osmosis around carbon stacking structures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:056321. [PMID: 21728661 DOI: 10.1103/physreve.83.056321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 01/31/2011] [Indexed: 05/31/2023]
Abstract
Broken symmetry of vortices due to induced-charge electro-osmosis (ICEO) around stacking structures is important for the generation of a large net flow in a microchannel. Following theoretical predictions in our previous study, we herein report experimental observations of asymmetrical reverse vortex flows around stacking structures of carbon posts with a large height (~110 μm) in water, prepared by the pyrolysis of a photoresist film in a reducing gas. Further, by the use of a coupled calculation method that considers boundary effects precisely, the experimental results, except for the problem of anomalous flow reversal, are successfully explained. That is, unlike previous predictions, the precise calculations here show that stacking structures accelerate a reverse flow rather than suppressing it for a microfluidic channel because of the deformation of electric fields near the stacking portions; these structures can also generate a large net flow theoretically in the direction opposite that of a previous prediction for a standard vortex flow. Furthermore, by solving the one-dimensional Poisson-Nernst-Plank (PNP) equations in the presence of ac electric fields, we find that the anomalous flow reversal occurs by the phase retardation between the induced diffuse charge and the tangential electric field. In addition, we successfully explain the nonlinearity of the flow velocity on the applied voltage by the PNP analysis. In the future, we expect to improve the pumping performance significantly by using stacking structures of conductive posts along with a low-cost process.
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Affiliation(s)
- Hideyuki Sugioka
- Frontier Research Center, Canon Inc., 30-2, Shimomaruko 3-chome, Tokyo 146-8501, Japan.
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49
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García-Sánchez P, Ramos A, González A. Effects of Faradaic currents on AC electroosmotic flows with coplanar symmetric electrodes. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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50
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Pascall AJ, Squires TM. An automated, high-throughput experimental system for induced charge electrokinetics. LAB ON A CHIP 2010; 10:2350-2357. [PMID: 20694256 DOI: 10.1039/c004926c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent experiments in induced charge electrokinetics (ICEK) have shown that the standard theory generally overpredicts experimentally observed velocities. Such discrepancies reduce the efficacy of practical ICEK devices, and highlight our incomplete understanding of electrokinetic phenomena. Here, we present an automated experimental system that allows for the rapid collection of ICEK data under a variety of conditions ( approximately 1000 per day) to help develop and constrain new theories. We demonstrate this system by studying the ICEK slip flows over electrodes that have been controllably "contaminated" with a dielectric layer, either SiO(2) or an alkanethiol self-assembled monolayer, of known thickness. We also develop a theory that accounts for the effects of the dielectric coatings surface chemistry that yields quantitative agreement with experiments over nearly a thousand distinct conditions in the SiO(2) system and present an additional three thousand experiments of flows over alkanethiol monolayers. Our experimental system allows the direct interrogation of the physico-chemical effects that influence ICEK flows and for the optimization of these flows in lab-on-a-chip systems.
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Affiliation(s)
- Andrew J Pascall
- Department of Chemical Engineering, University of California, Santa Barbara, USA
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