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    Multiphysics analysis and practical implementation of a soft μ-actuator- based microfluidic micromixer

    , Article Journal of Microelectromechanical Systems ; Volume 29, Issue 2 , 2020 , Pages 268-276 Annabestani, M ; Azizmohseni, S ; Esmaeili Dokht, P ; Bagheri, N ; Aghassizadeh, A ; Fardmanesh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    Electroactive-Polymers (EAPs) are one of the best soft $mu $ -actuators with great biomedical applications. Ionic ones (i-EAPs) have more promising features and have adequate potential for using in the active microfluidic devices. Here, as a case study, we have designed and fabricated a microfluidic micromixer using an i-EAP named Ionic Polymer-Metal Composite (IPMC). In microfluidics, active devices have more functionality but due to their required facilities are less effective for Point of Care Tests (POCTs). In the direction of solving this paradox, we should use some active components that they need minimum facilities. IPMC can be one of these components, hence by integrating the IPMC... 

    Low power receiver with merged N-path LNA and mixer for MICS applications

    , Article AEU - International Journal of Electronics and Communications ; Volume 117 , 2020 Beigi, A ; Safarian, A ; Sharif University of Technology
    Elsevier GmbH  2020
    Abstract
    In this paper, a low power receiver for medical implant communication service (MICS) is presented. Low power design is vital in the MICS applications since the implanted chip has to work for a long time without the need to change its battery. As a result, a merged N-path low noise amplifier (LNA) and mixer block is proposed. In this structure, the LNA and down-conversion mixer share a transconductance to lower the overall power consumption. An N-path feedback is utilized around the shared transconductance not only to improve the LNA selectivity and relax the linearity requirements but also to downconvert the radio frequency (RF) component and create the intermediate frequency (IF) signal. In... 

    Comparative analysis of different static mixers performance by CFD technique: An innovative mixer

    , Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 3 , 2020 , Pages 672-684 Haddadi, M. M ; Hosseini, S. H ; Rashtchian, D ; Olazar, M ; Sharif University of Technology
    Chemical Industry Press  2020
    Abstract
    The flow and mixing behavior of two miscible liquids has been studied in an innovative static mixer by using CFD, with Reynolds numbers ranging from 20 to 160. The performance of the new mixer is compared with those of Kenics, SMX, and Komax static mixers. The pressure drop ratio (Z-factor), coefficient of variation (CoV), and extensional efficiency (α) features have been used to evaluate power consumption, distributive mixing, and dispersive mixing performances, respectively, in all mixers. The model is firstly validated based on experimental data measured for the pressure drop ratio and the coefficient of variation. CFD results are consistent with measured data and those obtained by... 

    CFD modeling of immiscible liquids turbulent dispersion in Kenics static mixers: Focusing on droplet behavior

    , Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 2 , 2020 , Pages 348-361 Haddadi, M. M ; Hosseini, S. H ; Rashtchian, D ; Ahmadi, G ; Sharif University of Technology
    Chemical Industry Press  2020
    Abstract
    The present study is concerned with the computational fluid dynamics (CFD) simulation of turbulent dispersion of immiscible liquids, namely, water–silicone oil and water–benzene through Kenics static mixers using the Eulerian–Eulerian and Eulerian–Lagrangian approaches of the ANSYS Fluent 16.0 software. To study the droplet size distribution (DSD), the Eulerian formulation incorporating a population balance model (PBM) was employed. For the Eulerian–Lagrangian approach, a discrete phase model (DPM) in conjunction with the Eulerian approach for continuous phase simulation was used to predict the residence time distribution (RTD) of droplets. In both approaches, a shear stress transport (SST)... 

    Design and simulation of an integrated centrifugal microfluidic device for CTCs separation and cell lysis

    , Article Micromachines ; Volume 11, Issue 7 , July , 2020 Nasiri, R ; Shamloo, A ; Akbari, J ; Tebon, P ; Dokmeci, M. R ; Ahadian, S ; Sharif University of Technology
    MDPI AG  2020
    Abstract
    Separation of circulating tumor cells (CTCs) from blood samples and subsequent DNA extraction from these cells play a crucial role in cancer research and drug discovery. Microfluidics is a versatile technology that has been applied to create niche solutions to biomedical applications, such as cell separation and mixing, droplet generation, bioprinting, and organs on a chip. Centrifugal microfluidic biochips created on compact disks show great potential in processing biological samples for point of care diagnostics. This study investigates the design and numerical simulation of an integrated microfluidic device, including a cell separation unit for isolating CTCs from a blood sample and a... 

    Investigation of a Novel Microfluidic Device for Label-Free Ferrohydrodynamic Cell Separation on a Rotating Disk

    , Article IEEE Transactions on Biomedical Engineering ; Volume 67, Issue 2 , 2020 , Pages 372-378 Shamloo, A ; Besanjideh, M ; Sharif University of Technology
    IEEE Computer Society  2020
    Abstract
    Negative magnetophoresis is a novel and attractive method for continuous microparticle sorting inside a magnetic medium. In this method, diamagnetic particles are sorted based on their sizes using magnetic buoyancy force and without any labeling process. Although this method provides some attractive features, such as low-cost fabrication and ease of operation, there are some obstacles that adversely affect its performance, especially for biological applications. Most types of magnetic media, such as ferrofluids, are not biocompatible, and the time-consuming process of sample preparation can be threatening to the viability of the cells within the sample. Furthermore, in this method, both the... 

    Beamforming, null-steering, and simultaneous spatial and frequency domain filtering in integrated phased array systems

    , Article AEU - International Journal of Electronics and Communications ; Volume 110 , 2019 ; 14348411 (ISSN) Karami, P ; Atarodi, S. M ; Sharif University of Technology
    Elsevier GmbH  2019
    Abstract
    In the case that phased array systems are not capable of attenuating interferences, Radio Frequency (RF) front-ends and Analog Digital Converters (ADCs) with a large dynamic range are required to avoid saturation of the receiver. This leads to a higher power consumption. In this paper, employing N-path circuits in Mixer-First receivers, a novel method is introduced in which spatial and frequency blockers are eliminated right before entering the system on the antennas input. In fact using this technique, adjustable spatial notch filter and band-pass frequency filter are implemented to suppress spatial and frequency interferences. The proposed method enhances the robustness and effectiveness... 

    Enhancing active electro-kinetic micro-mixer efficiency by introducing vertical electrodes and modifying chamber aspect ratio

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 142 , 2019 ; 02552701 (ISSN) Maleki Bagherabadi, K ; Sani, M ; Saidi, M. S ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Micro-mixers are considered as vital components of Micro Total Analysis systems (μTAS). Major objective in the design of micro-mixers is achieving high mixing quality in short mixing times. In this paper, numerical simulation of some micro-mixer designs has been carried out to understand the detailed flow pattern and thereby to propose modifications for improving mixing efficiency. It is well known that inducing convection will provide turbulent like behavior with corresponding mixing enhancement. In micro systems to drive the flow, electro-osmotic force is usually used by introducing electrodes. In this work, mixing electrodes have been implemented to induce convection and eddies. This... 

    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  

    Numerical simulation of mixing and heat transfer in an integrated centrifugal microfluidic system for nested-PCR amplification and gene detection

    , Article Sensors and Actuators, B: Chemical ; Volume 283 , 2019 , Pages 831-841 ; 09254005 (ISSN) Naghdloo, A ; Ghazimirsaeed, E ; Shamloo, A ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Nucleic acid amplification via polymerase chain reaction (PCR) is one of the essential and powerful methods used in a myriad of bio-assays in clinical laboratories. Application of microfluidic devices in biologically-related processes like PCR can result in the usage of less volume of reactant samples and reduce the processing time. By implementing PCR systems on centrifugal microfluidic platforms, automation and portability can be easily achieved. Although several methods have been developed, most of them are still dealing with challenges of the required high processing time. This study presents the numerical simulation of a fully automated PCR system with the goal of enhancing the mixing... 

    A new non-dimensional parameter to obtain the minimum mixing length in tree-like concentration gradient generators

    , Article Chemical Engineering Science ; Volume 195 , 2019 , Pages 120-126 ; 00092509 (ISSN) Rismanian, M ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Microfluidic-based concentration gradient generators (CGGs) have a number of applications in chemical, biological and pharmaceutical studies. Thus, precise design of the microfluidic system is crucial to maintaining the desired concentration gradient in microchannels. One of the design considerations is the length of microchannels in the structure of a CGG. A CGG with a short length fails to provide the complete diffusive mixing, while the size of the microchip would unfavorably increase by incorporating a long CGG. Considering a CGG as a tree-like structure consisting of T-shaped micromixers, the mixing process of the species at a straight microchannel has been solved analytically. Herein,... 

    Effect of out-of-band blockers on the required linearity, phase noise, and harmonic rejection of sdr receivers without input saw filter

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 66, Issue 11 , 2018 , Pages 4913-4926 ; 00189480 (ISSN) Rasekh, A ; Bakhtiar, M. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    The required linearity of wideband receivers for applications, such as software-defined radio in the absence of input surface-acoustic wave (SAW) filters, is studied. It is shown that the required linearity of wideband SAW-less receivers is surprisingly higher than what has been commonly assumed. For these receivers, although the out-of-band blockers can reduce the compression point of the receiver, they can also potentially generate interferers that appear in the desired frequency band, resulting in higher noise floor and signal corruption. The required out-of-band IIP2 and IIP3 of low-noise amplifier (LNA) and mixer for single and concurrent applications are analytically derived. The... 

    A low-loss broadband quadrature signal generation network for high image rejection at millimeter-wave frequencies

    , Article IEEE Transactions on Microwave Theory and Techniques ; 2018 ; 00189480 (ISSN) Frounchi, M ; Alizadeh, A ; Coen, C. T ; Cressler, J. D ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    This paper presents a broadband low-loss quadrature-hybrid-based network that enhances the phase and the amplitude matching of quadrature signals. The performance of this network is investigated, and a detailed theoretical analysis is provided. Several stages of this network can be cascaded to generate broadband balanced quadrature signals. Each stage has a loss of 0.5 dB and enhances the image rejection ratio (IRR) by approximately 8 dB. Compared with the conventional polyphase quadrature signal generation methods, the proposed network enables lower insertion loss, wider bandwidth, and reduced sensitivity to process variations. To verify the theoretical analyses, two proof-of-concept... 

    Quantifying the direct influence of diffusive mass transfer in rarefied gas mixing simulations

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 140, Issue 3 , March , 2018 ; 00982202 (ISSN) Darbandi, M ; Sabouri, M ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2018
    Abstract
    This work utilizes the direct simulation Monte Carlo (DSMC) calculations and examines the influence of rarefication on the mixing length and effective diffusion coefficient in a two-species mixing problem. There have been efforts in past rarefied mixing flow studies to bridge between the mixing evolution rate and Knudsen number. A careful review of those efforts shows that the past derived relations did not determine the weights of Reynolds (or Peclet) number in the rarefaction influences. Although they indicated that an increase in Knudsen would decrease the mixing length, such reductions were primarily due to the Reynolds (or Peclet) reduction. Therefore, those studies could not explicitly... 

    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... 

    Three-dimensional numerical simulation of a novel electroosmotic micromixer

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 119 , 2017 , Pages 25-33 ; 02552701 (ISSN) Shamloo, A ; Madadelahi, M ; Abdorahimzadeh, S ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Lab-on-a-chip (LOC) systems have been widely used in chemical and medical analyses. In this study, a novel T-shaped electroosmotic micromixer was simulated and the effects of different parameters on the mixing process were examined. These parameters include; inlet angle, number of conducting hurdles, arrangements of the hurdles, geometry of hurdles and chambers, aspect ratios of the channel cross-sectional profile, hurdle radius, and depth. It was found that the inlet angle has a direct influence on mixing index (σ). The effect of various number of hurdles (one, two, three and four hurdles) and their orientations was investigated. Simulations revealed that using two conducting hurdles is the... 

    Rarefaction effects on gas mixing in micro- and nanoscales

    , Article ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016, 4 January 2016 through 6 January 2016 ; Volume 1 , 2016 ; 9780791849651 (ISBN) Darbandi, M ; Sabouri, M ; Heat Transfer Division ; Sharif University of Technology
    American Society of Mechanical Engineers  2016
    Abstract
    We present the rarefaction effects on diffusive mass transport in micro- and nanoscales using the results of direct simulation Monte Carlo DSMC method. Unlike the previous investigations, the momentum and heat contributions are eliminated from the computations via uniform velocity, pressure, and temperature field considerations. The effects of global Knudsen number on the diffusion phenomenon are studied for the same Peclet number and a unique mixer shape. The results indicate that there is considerable weakening in diffusion mechanism for high Knudsen number cases. As a result, the non-dimensional diffusive mass fluxes would decrease and the non-dimensional mixing length would increase as... 

    Numerical simulation for efficient mixing of newtonian and non-Newtonian fluids in an electro-osmotic micro-mixer

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 107 , 2016 , Pages 11-20 ; 02552701 (ISSN) Shamloo, A ; Mirzakhanloo, M ; Dabirzadeh, M. R ; Sharif University of Technology
    Elsevier  2016
    Abstract
    The present study, deals with a new mixing technique using a two-phase electrode array, which is charged with alternating current (AC) signals, located in specific parts of the geometry. This significantly contributes to a chaotic mixing mechanism using a low amplitude AC voltage within a micro-channel. Study analysis demonstrates that the optimization of the effective parameters such as geometrical features, voltage amplitude, fluid inlet velocity, AC frequency and phase lag for a defined fluid can lead to an optimum and highly efficient mixer by considerably increasing disturbances in a primary highly ordered laminar flow. Three different geometries of micro mixer are studied; one-ring... 

    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...