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    Parametric study on mixing process in an in-plane spiral micromixer utilizing chaotic advection

    , Article Analytica Chimica Acta ; Volume 1022 , 2018 , Pages 96-105 ; 00032670 (ISSN) Vatankhah, P ; Shamloo, A ; Sharif University of Technology
    Abstract
    Recent advances in the field of microfabrication have made the application of high-throughput microfluidics feasible. Mixing which is an essential part of any miniaturized standalone system remains the key challenge. This paper proposes a geometrically simple micromixer for efficient mixing for high-throughput microfluidic devices. The proposed micromixer utilizes a curved microchannel (spiral microchannel) to induce chaotic advection and enhance the mixing process. It is shown that the spiral microchannel is more efficient in comparison to a straight microchannel, mixing wise. The pressure drop in the spiral microchannel is only slightly higher than that in the straight microchannel. It is... 

    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... 

    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... 

    Numerical simulation of centrifugal serpentine micromixers and analyzing mixing quality parameters

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 104 , 2016 , Pages 243-252 ; 02552701 (ISSN) Shamloo, A ; Madadelahi, M ; Akbari, A ; Sharif University of Technology
    Elsevier, B.V  2016
    Abstract
    Centrifugal microfluidics or the Lab on a CD (LOCD) has developed vast applications in biomedical researches and analyses. Fluid mixing is an application of the LOCD. In this paper, multiple centrifugal micromixers were simulated. Various parameters were originally presumed to have an effect on mixing performance. These parameters include inlet angle, angular velocity, cross-sectional profile, perpendicular length ratio and the number of channels in series. They were each analyzed through simulations. It was gathered that the inlet angle does not significantly affect the mixing quality. Increasing angular velocity steadily increases mixing quality for all geometries. The vertical triangular... 

    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... 

    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... 

    A superconductor THz modulator based on vortex flux flow

    , Article IEEE Transactions on Applied Superconductivity ; Volume 19, Issue 4 , 2009 , Pages 3653-3657 ; 10518223 (ISSN) Sarreshtedari, F ; Hosseini, M ; Chalabi, H. R ; Moftakharzadeh, A ; Zandi, H ; Khorasani, S ; Fardmanesh, M ; Sharif University of Technology
    2009
    Abstract
    A terahertz modulator based on the Type-II superconductor flux flow oscillator has been proposed. Analytical calculations are presented and the effects of intrinsic and extrinsic parameters such as disorder strength of crystal, penetration depth, frequency, and amplitude of the modulated current on the radiation power spectrum have been studied. The proposed structure also exhibits a mixer-like behavior, in the sense that its output harmonics range from the washboard frequency up to the superconductor gap frequency, so the input signal is practically mixed with the washboard frequency and its harmonics. The modulation index for each harmonic of this modulator has also been investigated. This... 

    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... 

    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... 

    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... 

    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 90 nm-CMOS IR-UWB BPSK transmitter with spectrum tunability to improve peaceful UWB-narrowband coexistence

    , Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Vol. 61, issue. 6 , January , 2014 , p. 1836-1848 ; 15498328 Mir-Moghtadaei, S. V ; Fotowat-Ahmady, A ; Nezhad, A. Z ; Serdijn, W. A ; Sharif University of Technology
    Abstract
    A new ultra wideband (UWB) pulse generator covering a-10 dB bandwidth of 2.4-4.6 GHz with a tunable center frequency of 5-5.6 GHz to mitigate coexistence issues of impulse radio UWB (IR-UWB) systems and IEEE802.11.a WLAN or other narrowband (NB) systems in 90 nm-CMOS technology is proposed. The UWB pulse is generated based on frequency up-conversion of the first derivative of the Gaussian pulse, which creates an adjustable null in the frequency spectrum. Simulation results show that employing the proposed pulse generator mitigates the mutual interference between UWB and WLAN systems, significantly. The proposed transmitter consists of a low frequency signal generator, an LC oscillator and a... 

    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... 

    Down-conversion self-oscillating mixer by using CMOS technology

    , Article Proceedings - 2012 IEEE 8th International Colloquium on Signal Processing and Its Applications, CSPA 2012 ; 2012 , Pages 33-36 ; 9781467309615 (ISBN) Kouchaki, M ; Zahedi, A ; Sabaghi, M ; Ameri, S. R. H ; Niyakan, M ; Sharif University of Technology
    2012
    Abstract
    In this paper a self-oscillating mixer is presented fundamental signal generated by the oscillator subcircuit in the mixing process. The oscillator core consumes 3mA of current from a 1.8 V DC supply and results in an output power of -0.867 dBm per oscillator, and a measured phase noise of -91, -102 and -108 dBc/Hz at 100 KHz, 600 KHz and 1 MHz from the carrier, respectively. In the mixing process the proposed mixer achieved IIP3 of 0 dBm with conversation gain of 1.93 dB. The circuit was designed and simulated in 0.18-μm CMOS technology by ADS2010  

    An analytical approach in analysis of local oscillator near-the-carrier AM noise suppression in microwave balanced mixers

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 57, Issue 4 , 2009 , Pages 760-766 ; 00189480 (ISSN) Kheirdoost, A ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2009
    Abstract
    In this paper, a new formulation based on conversion matrix method is proposed to analyze near-the-carrier local ocillator (LO) noise down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely. © 2006 IEEE  

    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... 

    A 1-mW current reuse quadrature RF front-end for GPS L1 band in 0.18μm CMOS

    , Article 2012 19th IEEE International Conference on Electronics, Circuits, and Systems, ICECS 2012, Seville, Seville, 9 December 2012 through 12 December 2012 ; 2012 , Pages 157-160 ; 9781467312615 (ISBN) Jalili, H ; Fotowat Ahmady, A ; Jenabi, M ; Sharif University of Technology
    2012
    Abstract
    A new low-power current reuse topology is proposed for the GPS receiver's RF front-end that combines the higher conversion gain and suppressed noise figure characteristics of cascade structures with the low power consumption of stacked architectures. The presented circuit, called 1.5-stage LMV cell, consists of LNA, Mixer and VCO (LMV) in such a formation that boosts LNA gain and suppresses mixer's noise figure by cascading the two stages while reusing their currents in the two stacked quadrature VCOs and placing the mixer's upper tree switches at the vicinity of on-off regions. The circuit is designed and its layout is generated in TSMC 0.18μm CMOS technology. Post-layout simulations using...