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Suman Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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Electroosmosis-modulated peristaltic transport in microfluidic channels
Physics of Fluids, 2016Co-Authors: Aditya Bandopadhyay, Dharmendra Tripathi, Suman ChakrabortyAbstract:? 2016 Author(s).We analyze the peristaltic motion of aqueous electrolytes altered by means of applied electric fields. Handling electrolytes in typical peristaltic channel material such as polyvinyl chloride and Teflon leads to the generation of a net surface charge on the channel walls, which attracts counter-ions and repels co-ions from the aqueous solution, thus leading to the formation of an electrical double layer-a region of net charges near the wall. We analyze the spatial distribution of pressure and wall shear stress for a continuous wave train and single pulse peristaltic wave in the presence of an electrical (electroosmotic) body force, which acts on the net charges in the electrical double layer. We then analyze the effect of the electroosmotic body force on the particle reflux as elucidated through the net displacement of neutrally buoyant particles in the flow as the peristaltic waves progress. The impact of combined Electroosmosis and peristalsis on trapping of a fluid volume (e.g., bolus) inside the travelling wave is also discussed. The present analysis goes beyond the traditional analysis, which neglects the possibility of coupling the net pumping of fluids due to peristalsis and allows us to derive general expressions for the pressure drop and flow rate in order to set up a general framework for incorporating flow control and actuation by simultaneous peristalsis and application of electric fields to aqueous solutions. It is envisaged that the results presented here may act as a model for the design of lab-on-a-chip devices.
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ionic size dependent Electroosmosis in ion selective microchannels and nanochannels
Electrophoresis, 2013Co-Authors: Aditya Bandopadhyay, Suman ChakrabortyAbstract:Electrokinetics in salt-free media (in which counterions are only present) is central to the performance of many systems of modern technological relevance, ranging from ion-selective nanopores to electronic papers. Here, we introduce an analytical theory to describe the size dependence of Electroosmosis in such typical scenarios, exhibiting an interesting confluence of the implications of interdependence of the electroosmotic transport mechanisms, ionic sizes, and confinement dimensions along with the counterion concentration. Our results do reveal that the concerned mobility parameter, describing the strength of electroosmotic transport, increases simultaneously with increments in the surface charge density as well as an ionic size factor (also known as the steric factor), bearing far-ranging consequences in microfluidic and nanofluidic technology.
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Temperature Rise in Electroosmotic Flow of Typical Non-Newtonian Biofluids Through Rectangular Microchannels
Journal of Heat Transfer, 2013Co-Authors: Hadi Yavari, Mohammad Hassan Saidi, Arman Sadeghi, Suman ChakrabortyAbstract:Electroosmosis is the main mechanism for flow generation in lab-on-a-chip (LOC) devices. The temperature rise due to the Joule heating phenomenon, associated with the Electroosmosis, may be detrimental for samples being considered in LOCs. Hence, a complete understanding of the heat transfer physics associated with the electroosmotic flow is of high importance in design and active control of LOCs. The objective of the present study is to estimate the temperature rise and the thermal entry length in electroosmotic flow through rectangular microchannels, having potential applications in LOC devices. Along this line, the power-law rheological model is used to account for non-Newtonian behavior of the common biofluids encountered in these devices. A mixed type of thermal boundary condition is employed at the channel surface, instead of routinely presumed constant wall heat flux or constant wall temperature conditions. A finite difference-based numerical method is employed for solving the governing equations in dimensionless form. An approximate solution, based on the premise of a uniform temperature field throughout the channel cross section, is also obtained for the bulk mean temperature, which is found to be of high accuracy. This, accompanied by the assessments of the temperature profile, reveals that the temperature variations in the channel cross section are negligible, and as a result, the bulk mean temperature can be used as a very precise estimate of the maximum temperature in an LOC device. Moreover, the evaluation of the entry length shows that a thermally fully developed flow is hardly achieved in practical applications because of small length scales involved. Accordingly, the maximum temperature rise may significantly be smaller than what is calculated based on a thermally fully developed flow assumption.
Hilmi Mukhtar - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Electroosmosis and streaming potential for measurement of electric charges of polymeric membranes
Journal of Membrane Science, 1996Co-Authors: Kyujin Kim, A G Fane, Marianne Nystrom, Arto Pihlajamaki, W R Bowen, Hilmi MukhtarAbstract:Abstract Electrical properties for a range of commercial membranes have been determined by Electroosmosis and streaming potential measurements under identical conditions. For both techniques, the pH range was 3–7 and the electrolyte used was 10 −3 M KCl at 25°C, as the charges on the membrane are strongly dependent upon the pH and the ionic strength of the solution passing through the membrane. For both ultrafiltration (UF) and microfiltration (MF) membranes the absolute values of the apparent zeta potential determined from Electroosmosis were generally greater than those from streaming potential measurements with a greater difference at pH ≤ 4. The apparent zeta potentials obtained from Electroosmosis were negative for all membranes studied, even at pH below the isoelectric point where streaming potentials were positive. A substantial increase of the negative zeta potential at low pH (∼ pH 4) was interpreted in terms of the effect of the applied electric field on distribution of ions and differences in mobility of ions, particularly H + compared to the other ions. The magnitude of the zeta potentials determined from Electroosmosis exhibited an apparent difference due to change in orientation of the membrane for asymmetric UF membranes, whereas the streaming potential measurements showed less directional-effect for both UF and MF membranes.
Yasuhiro Horiike - One of the best experts on this subject based on the ideXlab platform.
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Low-voltage Electroosmosis pump for stand-alone microfluidics devices
ELECTROPHORESIS, 2003Co-Authors: Yuzuru Takamura, Hiroyuki Onoda, Hiromichi Inokuchi, Sakuichiro Adachi, Akio Oki, Yasuhiro HoriikeAbstract:Two types of low-voltage Electroosmosis pumps were developed using microfabrication technology for usage in handy or stand-alone applications of the micrototal analysis systems (micro-TAS) and the lab-on-a-chip. This was done by making a thin (< 1 microm) region in the flow path and by only applying voltages near this thin region using electrodes inserted into the flow path. The inserted electrodes must be free from bubble formation and be gas-tight in order to avoid pressure leakage. For these electrodes, Ag/AgCl or a gel salt bridge was used. For patterning the gel on the chip, a hydrophilic photopolymerization gel and a photolithographic technique were optimized for producing a gel with higher electric conductivity and higher mechanical strength. For high flow rate application, wide (33.2 mm) and thin (400 nm) pumping channels were compacted into a 1 mm x 6 mm area by folding. This pump achieves an 800 Pa static pressure and a flow of 415 nL/min at 10 V. For high-pressure application, a pump was designed with the thin and thick regions in series and positive and negative electrodes were inserted between them alternatively. This pump could increase the pumping pressure without increasing the supply voltage. A pump with 10-stage connections generated a pressure of 25 kPa at 10 V.
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Electroosmosis injection of blood serum into biocompatible microcapillary chip fabricated on quartz plate
Electrophoresis, 2001Co-Authors: Akio Oki, Sakuichiro Adachi, Yoshitaka Ito, Yuzuru Takamura, Takanori Ichiki, Hiroki Ogawa, Kazuhiko Ishihara, Yasuhiro HoriikeAbstract:A chip which allows the detection of various human health markers from a trace amount of blood has been studied. As a goal, a microcapillary with a 30 x 30 microm cross-section was fabricated using all-dry etching technologies on a 2 x 2 cm SiO2 chip. The coating of the biocompatible 2-methacryloyloxyethylphosphorylcholine (MPC) polymer on the inner quartz wall of the microcapillary demonstrated a sufficiently long adsorption suppression of proteins in the serum on the quartz surface, while rapid stopping occurred for serum injected into the microcapillary with a bare quartz surface. The latter rapid stopping corresponded well to fast Electroosmosis flow due to the negatively increasing zeta-potential by the adsorption of proteins on the quartz surface. The Electroosmosis pump arranged a downstream of the microcapillary was also developed to inject serum into it. As a preliminary application, a given concentration-standard solution was injected into the ion-sensitive field-effect transistor (ISFET) embedded in the chip, employing the Electroosmosis pump arranged downstream of the sensor position. Hence, the pH and Na+ and K+ cation concentrations were measured.
Dharmendra Tripathi - One of the best experts on this subject based on the ideXlab platform.
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Electroosmosis modulated transient blood flow in curved microvessels study of a mathematical model
Microvascular Research, 2019Co-Authors: V K Narla, Dharmendra TripathiAbstract:Abstract The flow through curved microvessels has more realistic applications in physiological transport phenomena especially in blood flow through capillary and microvessels. Motivated by the biomicrofluidics applications, a mathematical model is developed to describe the blood flow inside a curved microvessel driven by Electroosmosis. In addition to this flow, the channel experiences electric double layer phenomenon due to zeta potential about −25 mV. Lubrication theory and Debye-Huckel approximation are employed to obtain an analytical solution for electric potential function. Computations of stream function, axial velocity, volume flow rate, and pressure rise are computed through low zeta potentials. The electroosmotic flow behaviour is governed by two dimensionless parameters: Helmholtz-Smoluchowski velocity and Debye-Huckel parameter. It is also examined that, how curvature affects the blood flow driven by the Electroosmosis. Furthermore, the salient features of flow characteristics and trapping phenomena are presented. The results indicate that pressure gradient and wall shear stress reduce with increasing the curvature effects however the trapping is more with high curvature of the microvessel. The observations also indicate promising features of micromixer, micro-peristaltic pumps, and organ-on-a-chip devices. They may further be exploited in diagnosis/mixing of samples, and haemodialysis respectively.
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Electroosmosis modulated biomechanical transport through asymmetric microfluidics channel
Indian Journal of Physics, 2018Co-Authors: R Jhorar, Dharmendra Tripathi, M M Bhatti, R EllahiAbstract:This article addresses the electrokinetically modulated biomechanical transport through a two-dimensional asymmetric microchannel induced by peristaltic waves. Electrokinetic transport with peristaltic phenomena grabbed a significant attention due to its novel applications in engineering. Electrical fields also provide an excellent mode for regulating flows. The electrohydrodynamics problem is modified by means of Debye–Huckel linearization. Firstly, the governing flow problem is described by continuity and momentum equations in the presence of electrokinetic forces in Cartesian coordinates, then long wavelength and low/zero Reynolds (“neglecting the inertial forces”) approximations are applied to modify the governing flow problem. The resulting differential equations are solved analytically in order to obtain exact solutions for velocity profile whereas the numerical integration is carried out to analyze the pumping characteristics. The physical behaviour of sundry parameters is discussed for velocity profile, pressure rise and volume flow rate. In particular, the behaviour of electro-osmotic parameter, phase difference, and Helmholtz–Smoluchowski velocity is examined and discussed. The trapping mechanism is also visualized by drawing streamlines against the governing parameters. The present study offers various interesting results that warrant further study on electrokinetic transport with peristalsis.
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study of microvascular non newtonian blood flow modulated by Electroosmosis
Microvascular Research, 2018Co-Authors: Dharmendra Tripathi, Ashu Yadav, Anwar O Beg, Rakesh KumarAbstract:An analytical study of microvascular non-Newtonian blood flow is conducted incorporating the electro-osmosis phenomenon. Blood is considered as a Bingham rheological aqueous ionic solution. An externally applied static axial electrical field is imposed on the system. The Poisson-Boltzmann equation for electrical potential distribution is implemented to accommodate the electrical double layer in the microvascular regime. With long wavelength, lubrication and Debye-Huckel approximations, the boundary value problem is rendered non-dimensional. Analytical solutions are derived for the axial velocity, volumetric flow rate, pressure gradient, volumetric flow rate, averaged volumetric flow rate along one time period, pressure rise along one wavelength and stream function. A plug swidth is featured in the solutions. Via symbolic software (Mathematica), graphical plots are generated for the influence of Bingham plug flow width parameter, electrical Debye length and Helmholtz-Smoluchowski velocity (maximum electro-osmotic velocity) on the key hydrodynamic variables. This study reveals that blood flow rate accelerates with decreasing the plug width (i.e. viscoplastic nature of fluids) and also with increasing the Debye length parameter.
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thermal radiation effects on Electroosmosis modulated peristaltic transport of ionic nanoliquids in biomicrofluidics channel
Journal of Molecular Liquids, 2018Co-Authors: J Prakash, Ashish Sharma, Dharmendra TripathiAbstract:Abstract The flow characteristics of nanofluids flow driven by combined effects of Electroosmosis and peristalsis are very important for designing bio-mimetic pumping systems at the micro scale of interest in physiological treatment e.g. ocular drug delivery systems. The flow characteristics of thermally developed nanofluids flow are investigated in presence of peristalsis and Electroosmosis phenomena. Thermal radiation effect is also introduced. Tapered asymmetric microchannels are imposed at the walls to mimic sophisticated peristaltic wave propagation scenarios. The nanofluid is employed as the working fluid, and the analytical solution for electro-osmotic flow is obtained by virtue of the Debye–Huckel linearization. The dimensional conservation equations are linearized under lubrication theory approximations. The effects of emerging physical parameters namely Grashof numbers, Brownian motion parameter, thermophoresis parameter, Helmholtz-Smoluchowski velocity, Debye length and thermal radiation on flow characteristics, heat transfer characteristics, and pumping characteristics are computed. Furthermore, an inherent phenomenon of peristaltic pumping known as trapping is also presented graphically under the influence of pertinent parameters and discussed in brief. Validation of present model is also presented. This model is mainly applicable to study cell responses, blood analysis, biomimetic capillary designs, and blood vessel tissue culture systems.
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Electroosmosis-modulated peristaltic transport in microfluidic channels
Physics of Fluids, 2016Co-Authors: Aditya Bandopadhyay, Dharmendra Tripathi, Suman ChakrabortyAbstract:? 2016 Author(s).We analyze the peristaltic motion of aqueous electrolytes altered by means of applied electric fields. Handling electrolytes in typical peristaltic channel material such as polyvinyl chloride and Teflon leads to the generation of a net surface charge on the channel walls, which attracts counter-ions and repels co-ions from the aqueous solution, thus leading to the formation of an electrical double layer-a region of net charges near the wall. We analyze the spatial distribution of pressure and wall shear stress for a continuous wave train and single pulse peristaltic wave in the presence of an electrical (electroosmotic) body force, which acts on the net charges in the electrical double layer. We then analyze the effect of the electroosmotic body force on the particle reflux as elucidated through the net displacement of neutrally buoyant particles in the flow as the peristaltic waves progress. The impact of combined Electroosmosis and peristalsis on trapping of a fluid volume (e.g., bolus) inside the travelling wave is also discussed. The present analysis goes beyond the traditional analysis, which neglects the possibility of coupling the net pumping of fluids due to peristalsis and allows us to derive general expressions for the pressure drop and flow rate in order to set up a general framework for incorporating flow control and actuation by simultaneous peristalsis and application of electric fields to aqueous solutions. It is envisaged that the results presented here may act as a model for the design of lab-on-a-chip devices.
P Dario - One of the best experts on this subject based on the ideXlab platform.
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ac Electroosmosis in rectangular microchannels
Journal of Chemical Physics, 2005Co-Authors: Michele Campisi, Dino Accoto, P DarioAbstract:Motivated by the growing interest in ac Electroosmosis as a reliable no moving parts strategy to control fluid motion in microfluidic devices for biomedical applications, such as lab-on-a-chip, we study transient and steady-state electrokinetic phenomena (Electroosmosis and streaming currents) in infinitely extended rectangular charged microchannels. With the aid of Fourier series and Laplace transforms we provide a general formal solution of the problem, which is used to study the time-dependent response to sudden ac applied voltage differences in case of finite electric double layer. The Debye-Huckel approximation has been adopted to allow for an algebraic solution of the Poisson-Boltzmann problem in Fourier space. We obtain the expressions of flow velocity profiles, flow rates, streaming currents, as well as expressions of the complex hydraulic and electrokinetic conductances. We analyze in detail the dependence of the electrokinetic conductance on the extension of linear dimensions relative to the Deb...