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Total 44 records

    Temperature rise in electroosmotic flow of typical non-newtonian biofluids through rectangular microchannels

    , Article Journal of Heat Transfer ; Volume 136, Issue 3 , March , 2014 ; ISSN: 00221481 Yavari, H ; Sadeghi, A ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
    Abstract
    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... 

    3D modeling of reaction-diffusion dynamics in an electrokinetic Y-shaped microreactor

    , Article Sensors and Actuators, B: Chemical ; Volume 235 , 2016 , Pages 343-355 ; 09254005 (ISSN) Helisaz, H ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Elsevier  2016
    Abstract
    We perform a 3D numerical modeling of reaction-diffusion dynamics in a Y-shaped microreactor, considering a fully developed combined electroosmotic and pressure-driven flow. The governing equations, based on a second-order irreversible reaction, are solved invoking a finite-volume approach for a non-uniform grid system. We demonstrate that the reaction is highly position dependent: more production is observed adjacent to the horizontal walls for a favorable pressure gradient, whereas both the wall and centerline are the regions of highest production when a back pressure is applied. We further show that, to achieve the maximum production rate, the EDL should be thick enough, the pressure... 

    Polyamide/titania hollow nanofibers prepared by core–shell electrospinning as a microextractive phase in a fabricated sandwiched format microfluidic device

    , Article Journal of Chromatography A ; Volume 1528 , 2017 , Pages 1-9 ; 00219673 (ISSN) Rezvani, O ; Hashemi Hedeshi, M ; Bagheri, H ; Sharif University of Technology
    Abstract
    In this study, a low–cost microfluidic device from polymethyl methacrylate was fabricated by laser engraving technique. The device is consisted of a central chip unit with an aligned microchannel. Both sides of the engraved microchannel were sandwiched by two synthesized sheets from polyamide/titania (PA/TiO2) hollow nanofibers as extractive phases. The inlet and outlet of the device were connected to the polyether ether ketone tubes, while a peristaltic pump was used to deliver both sample and desorbing solvent through the microchannel. The recorded scanning electron microscopy images from the surface of the synthesized PA/TiO2 nanofibers, exhibit a good degree of homogeneity and porosity... 

    Reduction of production rate in y-shaped microreactors in the presence of viscoelasticity

    , Article Analytica Chimica Acta ; Volume 990 , 2017 , Pages 121-134 ; 00032670 (ISSN) Helisaz, H ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Abstract
    The viscoelasticity effects on the reaction-diffusion rates in a Y-shaped microreactor are studied utilizing the PTT rheological model. The flow is assumed to be fully developed and considered to be created under a combined action of electroosmotic and pressure forces. In general, finite-volume-based numerical simulations are conducted to handle the problem; however, analytical solutions based on the depthwise averaging approach are also obtained for the case for which there is no reaction between the inlet components. The analytical solutions are found to predict accurate results when the width to height ratio is at least 10 and acceptable results for lower aspect ratios. An investigation... 

    Carbon nanotubes in microfluidic lab-on-a-chip technology: current trends and future perspectives

    , Article Microfluidics and Nanofluidics ; Volume 21, Issue 9 , 2017 ; 16134982 (ISSN) Ghasemi, A ; Amiri, H ; Zare, H ; Masroor, M ; Hasanzadeh, A ; Beyzavi, A ; Aref, A. R ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Abstract
    Advanced nanomaterials such as carbon nanotubes (CNTs) display unprecedented properties such as strength, electrical conductance, thermal stability, and intriguing optical properties. These properties of CNT allow construction of small microfluidic devices leading to miniaturization of analyses previously conducted on a laboratory bench. With dimensions of only millimeters to a few square centimeters, these devices are called lab-on-a-chip (LOC). A LOC device requires a multidisciplinary contribution from different fields and offers automation, portability, and high-throughput screening along with a significant reduction in reagent consumption. Today, CNT can play a vital role in many parts... 

    Challenge in particle delivery to cells in a microfluidic device

    , Article Drug Delivery and Translational Research ; Volume 8, Issue 3 , 2018 , Pages 830-842 ; 2190393X (ISSN) Moghadas, H ; Saidi, M. S ; Kashaninejad, N ; Nguyen, N. T ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    Micro and nanotechnology can potentially revolutionize drug delivery systems. Novel microfluidic systems have been employed for the cell culture applications and drug delivery by micro and nanocarriers. Cells in the microchannels are under static and dynamic flow perfusion of culture media that provides nutrition and removes waste from the cells. This exerts hydrostatic and hydrodynamic forces on the cells. These forces can considerably affect the functions of the living cells. In this paper, we simulated the flow of air, culture medium, and the particle transport and deposition in the microchannels under different angles of connection inlet. It was found that the shear stress induced by the... 

    Design and fabrication of a centrifugal microfluidic disc including septum valve for measuring hemoglobin A1c in human whole blood using immunoturbidimetry method

    , Article Talanta ; Volume 190 , 2018 , Pages 134-139 ; 00399140 (ISSN) Mahmodi Arjmand, E ; Saadatmand, M ; Bakhtiari, M. R ; Eghbal, M ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Diabetes mellitus is a global endemic with a rapidly increasing prevalence in both developing and developed countries. Recently, hemoglobin A1c has been recommended by the American Diabetes Associations as a possible substitute for fasting blood glucose for the diagnosis of diabetes, because it is an indicator of long-term glycemic control. Also, centrifugal microfluidic systems have good potential for use in the point of care testing systems. In this study, a centrifugal microfluidic disc was designed and manufactured to measure hemoglobin A1c in whole blood using an immunoturbidimetry based method. Also, a new passive valve, named septum valve, was presented to precisely control the entry... 

    Design and simulation of a microfluidic device for acoustic cell separation

    , Article Ultrasonics ; Volume 84 , March , 2018 , Pages 234-243 ; 0041624X (ISSN) Shamloo, A ; Boodaghi, M ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Experimental acoustic cell separation methods have been widely used to perform separation for different types of blood cells. However, numerical simulation of acoustic cell separation has not gained enough attention and needs further investigation since by using numerical methods, it is possible to optimize different parameters involved in the design of an acoustic device and calculate particle trajectories in a simple and low cost manner before spending time and effort for fabricating these devices. In this study, we present a comprehensive finite element-based simulation of acoustic separation of platelets, red blood cells and white blood cells, using standing surface acoustic waves... 

    Newtonian and generalized Newtonian reacting flows in serpentine microchannels: pressure driven and centrifugal microfluidics

    , Article Journal of Non-Newtonian Fluid Mechanics ; Volume 251 , January , 2018 , Pages 88-96 ; 03770257 (ISSN) Madadelahi, M ; Shamloo, A ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    This paper presents a comprehensive 3D numerical simulation of reacting flows in micro scale dimension through centrifugal, or Lab-On-a-CD (LOCD), and pressure-driven, or Lab-On-a-Chip (LOC) devices. Three different serpentine channel configurations (rectangular, triangular and sinusoidal) are investigated. In these configurations, two chemical species enter from two inlets and according to an irreversible chemical reaction, start yielding other species. Both Newtonian and generalized Newtonian fluids are considered in the simulations and the results are compared for both LOC and LOCD devices. Besides, the effects of different parameters such as the aspect ratio of channels’ cross section,... 

    Modeling, simulation, and employing dilution–dialysis microfluidic chip (DDMC) for heightening proteins refolding efficiency

    , Article Bioprocess and Biosystems Engineering ; Volume 41, Issue 5 , 2018 , Pages 707-714 ; 16157591 (ISSN) Kashanian, F ; Masoudi, M. M ; Shamloo, A ; Habibi Rezaei, M ; Moosavi Movahedi, A. A ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    Miniaturized systems based on the principles of microfluidics are widely used in various fields, such as biochemical and biomedical applications. Systematic design processes are demanded the proper use of these microfluidic devices based on mathematical simulations. Aggregated proteins (e.g., inclusion bodies) in solution with chaotropic agents (such as urea) at high concentration in combination with reducing agents are denatured. Refolding methods to achieve the native proteins from inclusion bodies of recombinant protein relying on denaturant dilution or dialysis approaches for suppressing protein aggregation is very important in the industrial field. In this paper, a modeling approach is... 

    Numerical Simulation and Enalysis of an Electrokinetically-driven Microdispenser

    , M.Sc. Thesis Sharif University of Technology Haroutunian, Artin (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Shafiee, Mohammad Behshad (Supervisor)
    Abstract
    Nowadays Lab-on-a-chip systems are being widely used in medical applications, especially in analyzing minute volumes of blood for diagnosis and treatment of some crucial diaseses like diabetic. A Lab-on-a-chip is comprised of a variety of components such as micromixer, microdispenser, detection and separation units and so on. In this thesis, however, we have analyzed and numerically simulated a microdispenser which is electrokinetically driven. In other words, electrical potentials are applied to electrodes in order to conduct two fluids within a cross microchannel, and distribution of a sample fluid takes place due to appropriately applied potentials. In order to analyze and simulate the... 

    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... 

    Flow of Saliva in a Lab-on-a-chip under Electrokinetic Body Force

    , M.Sc. Thesis Sharif University of Technology Zandi, Mohammad (Author) ; Saeedi, Mohammad Hassan (Supervisor)
    Abstract
    The lab-on-a-chip (LOC) devices utilizing electroosmosis for flow actuation are usually encountered with non-Newtonian behavior of working fluids. Hence, studying the flow of non-Newtonian fluids under an electroosmotic body force is of high importance for accurate design and active control of these devices. In this thesis, mixed electroosmotically and pressure driven flow of salivathrough a rectangular microchannel is examined utilizing two viscoelastic constitutive equations, namely PTT and FENE-P models. Since the hydrodynamic entry length is usually negligible for microflows, a hydrodynamically developed flow is considered in the analysis. The governing equations in dimensionless form... 

    Transport Phenomena in Electrokinetically Generated Microflows

    , Ph.D. Dissertation Sharif University of Technology Sadeghi, Arman (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Mozaffari, Ali Asghar (Supervisor) ; Chakraborty, Suman (Co-Advisor)
    Abstract
    This is a theoretical study on heat and mass transfer in electrokinetically driven microfluidic devices with particular consideration to the lab-on-a-chip (LOC) applications. Special attention is given to disclose the effects of the fluid rheology and the aspect ratio of the rectangular geometry on the surface reaction kinetics and the temperature rise due to the Joule heating. Along this line, two different viscoelastic constitutive equations namely PTT and FENE-P models along with the power-law viscosity model are being considered. The secondary aims also include exploring the influences of the fluid properties variations throughout the channel cross section on the hydrodynamic and thermal... 

    Microfluidic devices with gold thin film channels for chemical and biomedical applications: a review

    , Article Biomedical Microdevices ; Volume 21, Issue 4 , 2019 ; 13872176 (ISSN) Ghasemi Toudeshkchoui, M ; Rabiee, N ; Rabiee, M ; Bagherzadeh, M ; Tahriri, M ; Tayebi, L ; Hamblin, M. R ; Sharif University of Technology
    Springer New York LLC  2019
    Abstract
    Microfluidic systems (MFS) provide a range of advantages in biomedical applications, including improved controllability of material characteristics and lower consumption of reagents, energy, time and money. Fabrication of MFS employs various materials, such as glass, silicon, ceramics, paper, and metals such as gold, copper, aluminum, chromium and titanium. In this review, gold thin film microfluidic channels (GTFMFC) are discussed with reference to fabrication methods and their diverse use in chemical and biomedical applications. The advantages of gold thin films (GTF) include flexibility, ease of manufacture, adhesion to polymer surfaces, chemical stability, good electrical conductivity,... 

    A foreign body response-on-a-chip platform

    , Article Advanced Healthcare Materials ; Volume 8, Issue 4 , 2019 ; 21922640 (ISSN) Sharifi, F ; Htwe, S. S ; Righi, M ; Liu, H ; Pietralunga, A ; Yesil Celiktas, O ; Maharjan, S ; Cha, B. H ; Shin, S. R ; Dokmeci, M. R ; Vrana, N. E ; Ghaemmaghami, A. M ; Khademhosseini, A ; Zhang, Y. S ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    Abstract
    Understanding the foreign body response (FBR) and desiging strategies to modulate such a response represent a grand challenge for implant devices and biomaterials. Here, the development of a microfluidic platform is reported, i.e., the FBR-on-a-chip (FBROC) for modeling the cascade of events during immune cell response to implants. The platform models the native implant microenvironment where the implants are interfaced directly with surrounding tissues, as well as vasculature with circulating immune cells. The study demonstrates that the release of cytokines such as monocyte chemoattractant protein 1 (MCP-1) from the extracellular matrix (ECM)-like hydrogels in the bottom tissue chamber... 

    Design a Microfluidics System for Drug Testing of Leukemia Patient's Bone Marrow Aspirate

    , M.Sc. Thesis Sharif University of Technology Rahimi, Ali (Author) ; Saidi, Mohammad Said (Supervisor)
    Abstract
    Cancer is one of the most causes of mortality in the world. Leukemia is a type of cancer initiated by the rapid proliferation of blood cells including WBCs, RBCs, and Platelets, that classified into four general types of AML, ALL, CML, and CLL. The main treatment of leukemia is chemotherapy. Because of many problems that patients have with this treatment and not so good results of chemotherapy, we design a microfluidic chip that can perform personalized medicine treatment for leukemia patients.This microchip consists of two main parts, Concentration Gradient Generator (CGG), and cell culture. CGG system is a tree CGG with two inlets and four outlets, which makes a linear concentration of... 

    A tool for designing tree-like concentration gradient generators for lab-on-a-chip applications

    , Article Chemical Engineering Science ; Volume 212 , 2020 Ebadi, M ; Moshksayan, K ; Kashaninejad, N ; Saidi, M. S ; Nguyen, N. T ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Concentration gradient generators (CGGs) help biologists to perform large scale, fast and high-throughput experiments. This paper introduces a design tool called Tree-like Concentration gradient generator Design Tool (TCDT). The performance of this tool is validated both numerically and experimentally. Three CGGs were fabricated using three different fabrication methods and design parameters. The performance of these devices was examined using the measurement of fluorescent and dye intensity. The performance of the design tool for non-linear and multi-drug concentration gradient generations was investigated as well. In addition, a method was developed to investigate the multi-drug... 

    Microfluidic-based approaches in targeted cell/particle separation based on physical properties: fundamentals and applications

    , Article Small ; Volume 16, Issue 29 , 2020 Nasiri, R ; Shamloo, A ; Ahadian, S ; Amirifar, L ; Akbari, J ; Goudie, M. J ; Lee, K ; Ashammakhi, N ; Dokmeci, M. R ; Di Carlo, D ; Khademhosseini, A ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    Cell separation is a key step in many biomedical research areas including biotechnology, cancer research, regenerative medicine, and drug discovery. While conventional cell sorting approaches have led to high-efficiency sorting by exploiting the cell's specific properties, microfluidics has shown great promise in cell separation by exploiting different physical principles and using different properties of the cells. In particular, label-free cell separation techniques are highly recommended to minimize cell damage and avoid costly and labor-intensive steps of labeling molecular signatures of cells. In general, microfluidic-based cell sorting approaches can separate cells using “intrinsic”...