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    A microfluidic concentration gradient generator for simultaneous delivery of two reagents on a millimeter-sized sample

    , Article Journal of Flow Chemistry ; Volume 10, Issue 4 , 2020 , Pages 615-625 Rismanian, M ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
    Springer International Publishing  2020
    Abstract
    Microfluidic concentration gradient generators (μCGGs) are indispensable parts of many emerging lab-on-a-chip platforms for biological studies and drug delivery applications. Most of the μCGGs reported in the literature can only generate the desired concentration gradients in a micron-sized sample (e.g., cells). As such, there is an unmet need to design a μCGG that can generate continuous concentration gradients of multi reagents (e.g., drugs) in a millimeter-sized sample (e.g., tissue). Herein, we report the proof-of-concept of this class of μCGG by combining a modified tree-like CGG with a micromixer. By conducting both experimental investigation and numerical analysis, we show that the... 

    Computational Simulation of Micromixing, Using LBM

    , M.Sc. Thesis Sharif University of Technology Hosseini-zade, Mohammad (Author) ; Taeibi-Rahni, Mohammad (Supervisor)
    Abstract
    Nowadays, microfluidic flow appears in many applications, such as medical, biological, and chemical industries. Where as, micromixing, which deals with mixing of microfluidic flow in micro channels, appears to be an important issue to many researchers. In such systems, molecular diffusion plays an important role. On the other hand, lattice Boltzmann method is a relatively new simulation technique for complex fluid systems and has become interesting to many researchers in computational physics. In this study, computational simulation of such mixing process, using LBM is the main objective. Different obstacle layouts inside a microchannel have been investigated. Chaotic advection and jet... 

    Numerical Simulation and Characterization of a Micro-mixer with Moving Walls

    , M.Sc. Thesis Sharif University of Technology Omidvar, Ahmad Reza (Author) ; Saeedi , Mohammad Saeed (Supervisor) ; Sani, Mahdi (Supervisor)
    Abstract
    Recent advances in micro-technology are finding important applications especially in chemical and biological processes. In these applications, mixing has a profound importance. Due to the inherent low Reynold’s number flow in micro systems, diffusion mixing is the dominant mixing mechanism at these scales. This is in contrary to the high Reynold’s number ordinary applications where turbulent mixing plays the major role. There are two major classes of micro-mixers: passive and active. Passive micro-mixers rely on geometric features to enhance mixing. Active micro-mixers on the other hand, use external excitation to promote and control the rate of mixing. In this work, using numerical tools,... 

    Numerical Simulation and Analysis of Active Electro-Kinetic Micro-Mixer

    , M.Sc. Thesis Sharif University of Technology Maleki Bagherabadi, Kamyar (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Sani, Mahdi (Supervisor)
    Abstract
    The “Lab-on-a-Chip” is a micro-scale device which uses fluids as working medium and can handle number of functions such as sample preparation and transfer, separation, bio-sensing and detection. One of the important parts of these devices is micro-mixer, that should blend two fluid species in a short time with desirable mixing quality. Micro-mixers are classified as passive and active. By considering the micro-scale of mixers, turbulence phenomena cannot occur due to dominance of viscous forces, therefore the mixing only depends on molecular diffusion. This thesis consists of two main parts, in the first part algebraic multigrid has been studied and implemented in Rayan (in-house CFD code).... 

    Active microfluidic micromixer design using ionic polymer-metal composites

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 371-375 ; 9781728115085 (ISBN) Annabestani, M ; Mohammadzadeh, H ; Aghassizadeh, A ; Azizmohseni, S ; Fardmanesh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    In most of the microfluidic applications, it is necessary to have a mixed fluid from the beginning, but in microchannels, due to facing with low Reynolds flows, the fluids flow in the channel by the laminar regimes. Hence the mixing process is a challenging problem and researchers are trying to present fast and reliable micromixers. In this paper, using Ionic Polymer-Metal Composites (IPMCs), an active micromixer has been designed. To investigate the appropriateness of IPMC, using experimental and simulation tests, we show that the IPMC actuator is a potential candidate as an active element of microfluidic micromixers  

    Investigation of the Geometry Effect on Electrokinetic Instability in Microflows

    , M.Sc. Thesis Sharif University of Technology Mohammadzadeh, Alireza (Author) ; Saidi, Mohammad Hassan (Supervisor)
    Abstract
    Lab-on-a-chip devices have gained a lot of attention in chemical and biomedical analyses during the past two decades. These devices employ microfluidics basics and fundamentals to combine multifold laboratory processes in one single portable chip. The electric field has been often used in most microfluidics applications for the ease of sample control as well as become easily integrated to other chip components. Instabilities in microflows would occur when two fluids of different electric properties are exposed to an adequately strong electric field. Studying these electrokinetic instabilities is not only important for the fundamental studies but also for practical applications in micromixers... 

    Numerical and Analytical Study of Mixing in Y-shaped Micromixers: Electroosmotic and Poiseuille Flow of PTT Fluids

    , M.Sc. Thesis Sharif University of Technology Reshadi, Milad (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Mozaffari, Ali Asghar (Supervisor)
    Abstract
    Dissemination of an analyte under the laminar flows plays a major role in measuring and assessment of biological fluids such as sample preparation in the context of microfluidic systems. Due to the development of manufacturing technology in the Lab-on-a-chip devices, the production of rectangular microchannels with finite aspect ratios and micron and submicron sizes has been provided by which the effect of electrokinetic phenomena on concentration distribution will be magnified in these systems. On the other hand, these biofluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids and adopting appropriate constitutive equations these exotic flow behaviors... 

    Analysis and Design of an Electrokinetically-driven Micro-Mixer

    , M.Sc. Thesis Sharif University of Technology Anbari, Ali Mohammad (Author) ; Shafii, Mohammad Behshad (Supervisor) ; Saeedi, Mohammad Saeed (Supervisor)
    Abstract
    A Lab-On-A-Chip is a micro-scale system whic h utilizes some micro-scale components in order to implement detection tests on samples. One of the most important components of a lab-on-a-chip device is the micro-mixer, which is responsible for appropriately mixing of samples in a short period of time. The biggest problem relevant to mixing in micro scales is that since as the viscous forces are dominant in micro scale and dimensions are small, it is impractical to mix fluids via turbulence, and consequently mixing process is performed by diffusion mechanism. Two major strategies are being used in order to improve the mixing performance and two groups of micro-mixers, passive and active types,... 

    Numerical Simulation and Analysis of Electrokinetic Micromixer

    , M.Sc. Thesis Sharif University of Technology Raffiee, Amir Hossein (Author) ; Saidi, Mohammad Said (Supervisor)
    Abstract
    Lab-On-A-Chip is a micro-scale system which utilizes specific tools in order to operate detection tests on samples. One of the most important components of these devices is micromixers which is responsible for appropriate mixing of samples in short period of time. The biggest problem associated to the mixing in micro-scale is the regime that the flow takes during the process. Due to the small dimensions of micromixers the induced flow stream resides in the range of laminar flows and consequently the mixing is conducted solely by diffusion mechanism which is either time-taking or requires long micro-channel that causes the high cost of fabrication. In order to improve the mixing process two... 

    Isolation of Circulating Tumor Cells Using an Aptamer-Based Microfluidic Device

    , M.Sc. Thesis Sharif University of Technology Abouali, Hesam (Author) ; Vosoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Supervisor)
    Abstract
    Cancer is a major cause of mortality worldwide, with a disease burden estimated to grow over the coming decades. Circulating tumor cells (CTCs) are rare cancer cells released from the primary or metastatic tumors and transported though the peripheral circulatory system to their specific secondary locations. The presence of CTCs in a cancer patient’s blood has been used as a prognostic biomarker, with lower CTC count correlating with greater overall survival. In spite of its clinical potential, the isolation and detection of CTCs has been a challenging task due to its rare presence amongst other blood cells (as low as 1–10 CTCs per billions of blood cells) and variability in terms of both... 

    Production of Vegetable Oil Biodiesel by Heterogeneous Catalytic Trans-Esterification Method in Micro-Reactor

    , M.Sc. Thesis Sharif University of Technology Piran, Samira (Author) ; Kazemeini, Mohammad (Supervisor) ; Mohammadi, Ali Asghar (Supervisor)
    Abstract
    The purpose of this study is to study heterogeneous nanocatalysts for the production of biofuels by the method of exchange of styrene using oil and methanol as a fossil fuel alternative. Preparation of nanocatalysts, performing characteristic tests and investigating the reaction in different operating conditions in the batch reactor has already been studied. Therefore, in this study, the production of biodiesel fuel using the trans-esterification of canola oil with nanocatalysts in the micro-reactor reactor will be discussed. Previously, a heterogeneous catalyst (lithium based on calcium-lanthanum) was constructed using a co-incineration method and a wet inoculum, and as active and stable... 

    Modeling active micromixers with multiple microstirrers using smoothed particle hydrodynamics

    , Article Scientia Iranica ; Vol. 21, issue. 4 , 2014 , pp. 1390-1402 ; ISSN: 10263098 Jafarian, A ; Pishevar, A ; Saidi, M. S ; Sharif University of Technology
    Abstract
    The smoothed particle hydrodynamics method is used to explore the effects of design parameters on the mixing efficiency of two types of active micromixer. First, the complex flow field and the mixing process of two separated fluids in a square mixing chamber with nine symmetric microstirrers are simulated. The influence of design parameters, such as the microstirrer rotation arrangement and the angular velocity of the microstirrer, on the mixing performance, is investigated. The mixing index parameter on ten control points is calculated and the average mixing index is compared for different cases. Simulations illustrate that the rotation arrangement of microstirrers is a key parameter in the... 

    Analyzing mixing quality in a curved centrifugal micromixer through numerical simulation

    , Article Chemical Engineering and Processing: Process Intensification ; 2017 ; 02552701 (ISSN) Shamloo, A ; Vatankhah, P ; Akbari, A ; Sharif University of Technology
    Elsevier B.V 
    Abstract
    The Lab On a CD (LOCD), also known as Centrifugal Microfluidics, has evolved into a sophisticated platform for performing biomedical assays due to its marvelous miniaturization and accurate simulation of biological reactions. Among the numerous applications of the LOCD is fluid mixing. In this paper a centrifugal, serpentine micromixer is simulated and reformed toward better mixing performance. The micromixer was chosen to be curved as a curved design was found to be thrice as functional and compact as a rectilinear design, mixing-wise. The two angular velocity and opening radius parameters were originally hypothesized to affect mixing performance. Effect of angular velocity was studied over... 

    Mixing performance of T, Y, and oriented Y-micromixers with spatially arranged outlet channel: evaluation with villermaux/dushman test reaction

    , Article Microsystem Technologies ; 2016 , Pages 1-14 ; 09467076 (ISSN) Rahimi, M ; Azimi, N ; Parsamogadam, M. A ; Rahimi, A ; Masahy, M. M ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    This study aims to investigate the micromixing performance of three basic types of spatial shaped micromixers. New configurations of T, Y, and oriented Y-spatial mixers were designed with change in the angles of the confluence and the outlet channel to achieve the efficient micromixing. These micromixers offer advantages that are not attainable with the typical types of these mixers. Experimental tests were carried out in the laminar flow regime and the mixing efficiency was evaluated using Villermaux/Dushman test reaction. The geometries of the channels were cylindrical with the length of 30 mm and the diameter of 800 μm. The experimental results show that the angle of outlet channel has a... 

    Mixing performance of T, Y, and oriented Y-micromixers with spatially arranged outlet channel: evaluation with Villermaux/Dushman test reaction

    , Article Microsystem Technologies ; Volume 23, Issue 8 , 2017 , Pages 3117-3130 ; 09467076 (ISSN) Rahimi, M ; Azimi, N ; Parsamogadam, M. A ; Rahimi, A ; Masahy, M. M ; Sharif University of Technology
    Springer Verlag  2017
    Abstract
    This study aims to investigate the micromixing performance of three basic types of spatial shaped micromixers. New configurations of T, Y, and oriented Y-spatial mixers were designed with change in the angles of the confluence and the outlet channel to achieve the efficient micromixing. These micromixers offer advantages that are not attainable with the typical types of these mixers. Experimental tests were carried out in the laminar flow regime and the mixing efficiency was evaluated using Villermaux/Dushman test reaction. The geometries of the channels were cylindrical with the length of 30 mm and the diameter of 800 μm. The experimental results show that the angle of outlet channel has a... 

    Analyzing mixing quality in a curved centrifugal micromixer through numerical simulation

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 116 , 2017 , Pages 9-16 ; 02552701 (ISSN) Shamloo, A ; Vatankhah, P ; Akbari, A ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    The Lab On a CD (LOCD), also known as Centrifugal Microfluidics, has evolved into a sophisticated platform for performing biomedical assays due to its marvelous miniaturization and accurate simulation of biological reactions. Among the numerous applications of the LOCD is fluid mixing. In this paper a centrifugal, serpentine micromixer is simulated and reformed toward better mixing performance. The micromixer was chosen to be curved as a curved design was found to be thrice as functional and compact as a rectilinear design, mixing-wise. The two angular velocity and opening radius parameters were originally hypothesized to affect mixing performance. Effect of angular velocity was studied over... 

    Experimental Investigation and Modeling of Nanoparticles Synthesis by Reactive Precipitation and Using a Spinning Disk Reactor

    , Ph.D. Dissertation Sharif University of Technology Bagheri Farahani, Hamed (Author) ; Shahrokhi, Mohammad (Supervisor) ; Molaei Dehkordi, Asghar (Supervisor)
    Abstract
    In this research work, to enhance the performance of the conventional spinning disk reactors, a novel type of spinning disk reactor has been proposed and tested successfully through the synthesis of barium sulfate nanoparticles by means of the reactive precipitation. This reactor consists of two coaxial rotating disks placed horizontally in a cylindrical chamber. The experimental results clearly indicate the capability of the proposed reactor in the synthesis of nanoparticles with the smaller mean particle size and the narrower particle size distribution compared to those obtained in various process intensification devices such that barium sulfate nanoparticles with a mean particle size of... 

    Ionic Size and Rheology Effects on the Mixing Process of Electroosmotic Flows

    , M.Sc. Thesis Sharif University of Technology Ahmadian Yazdi, Alireza (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Mozaffari, Ali Asghar (Supervisor)
    Abstract
    In recent years, there have been huge advancements in fabrication of micron-sized devices such that they enabled engineers to create a wide range of miniaturized systems, each of which is utilized in mechanical, electrical, and thermal applications. Micromixers are one of these devices with the role of mixing various micro flows. These devices are broadly used for chemical, biological, and biomedical assays. Among variety of micromixers, one that employs electrokinetic transport phenomenon is of great popularity. For instance, mixing under electroosmotic flow enables accurate process control and eliminates the need for moving components inside micromixer. The very complex nature of electric... 

    Modeling and Simulation of Micromixing Phenomenon in a New Double-Spinning-Disc Reactor

    , M.Sc. Thesis Sharif University of Technology Balaghi Inaloo, Majid (Author) ; Molaei Dehkordi, Asghar (Supervisor)
    Abstract
    Mixing efficiency is an important performance indicator in many chemical reactors. In the present study, using a computational fluid dynamics model, the quality of micromixing in a double-disk-spinning reactor with the ability to rotate both disks using a fast iodide-iodate competitive reaction has been investigated. The purpose of this study was to investigate the effect of operational parameters such as the speed and direction of rotation of disks, radius and number of entry points of one feed, distance between disks, volumetric flow of feed, feed inlet nozzle diameter and acid concentration (H+) on quality of micromixing. The simulation results show that by increasing the rotation speed... 

    Rheology Effects on Reaction-diffusion Mechanisms in a Y-shaped Micro Fluidic Mixer

    , M.Sc. Thesis Sharif University of Technology Hellisaz, Hamed (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Kazemzadeh Hannani, Siamak ($item.subfieldsMap.e)
    Abstract
    Numerous applications of Lab on a Chips (LOCs) in chemical/biochemical analyses as well as the emergence of advanced methods for their manufacture attracts many researchers’ attention to these micro instruments. Low sample volume consumption and their high controllability are accounted as the main advantage of LOC systems. Micromixers are among the main components of any LOC in which mixing and/or reaction among two components occur. Micromixers have many potential applications in biological and medical sciences, and so they are repeatedly charged by biofluids. Due to sensibility of biofluids, to avoid disintegration, applying electroosmotic flow instead of pressure-induced flow has priority...