Search for: concentration-gradients
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 ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Springer International Publishing 2020
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...
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) ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Elsevier Ltd 2019
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,...
Design and Fabrication of Micro-Fluidic Chip for Formation, Culture and Analysis of Cancer Tumor Cell Spheroids, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Saeed ; Kazemzadeh Hannani, Siamak
Simulating the in-vivo environment of cancer tumors outside the body, can provide an appropriate condition for studying different key processes of the tumor micro-environment, such as aggregation, formation, growth, angiogenesis and metastasis of the cancer tumor cells, which can be useful in finding methods to cure, or at least control cancer. Every year, a variety of drugs are being developed to overcome cancer, all of which need to be experimented. Although, these drugs are now experimented on animals, and some human volunteers, the reaction of different patients’ cancer cells to different drugs may differ with the experimented animals, or even with other people. So, there needs to be a...
Article Proceedings of the IASTED International Conference on Biomedical Engineering, BioMed 2014 ; 2014 , pp. 83-88 ; Abeddoust, M ; Mehboudi, N ; Sharif University of Technology
Many potential therapies are currently being studied that may promote neural regeneration and guide regenerating axons to form correct connections following injury. It has been shown that adult neurons have some limited regenerative capabilities, and the lack of connection formation between neurons is not an intrinsic inability of these cells to form axons after being damaged, but rather the inhibitory microenvironment of the injured tissue prevents regeneration. In this study, the polarization and chemotaxis of neuronal stem cells (NSC) in response to quantified gradients of nerve growth factor (NGF) was examined. To accomplish this, a microfluidic device was designed and fabricated to...
M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Said
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...
M.Sc. Thesis Sharif University of Technology ; kashaninezhad, navid
Nowadays, due to the growing need of the human to further improve the health of the community, research in the field of pharmacology as well as simulation of the cell culture environment is increasing. One of the most important requirements for simulating cell culture is the use of concentration gradient in culture media. The reason for this is the dependence of cellular activity on the presence of a gradient of concentration in the environment. Also, in drug investigations, in order to speed up the examination of different drugs and reduce the amount of drug that will used, different concentrations of the drug should be considered simultaneously in the microchips. Therefore, to make the...
Design and Fabrication of a Microfluidic System for Simultaneous Delivery of Two Reagents on a Millimeter-Sized Tissue, Ph.D. Dissertation Sharif University of Technology ; Saeedi, Mohamad Saeed ; Kashaninejad, Navid
It is of great interest to investigate the effects of different concentrations of chemical species on the behavior of test samples. For example, while developing a new drug, pharmacologists are concerned with the behavior of the live sample against different drug concentrations. Microfluidic systems are the new engineering platforms developed for simplifying these experiments. The main goal of the current study is the design and fabrication of a microfluidic system with the capability of generating a continuous concentration gradient from two species simultaneously on a millimeter-sized test sample. Such a system creates many benefits for researchers using microfluidics technology. Our...
Article Chemical Engineering Science ; Volume 212 , 2020 ; Moshksayan, K ; Kashaninejad, N ; Saidi, M. S ; Nguyen, N. T ; Sharif University of Technology
Elsevier Ltd 2020
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...
M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Saeed ; Hajilouy Benisi, Ali ; Moghadas, Hajar
In this manuscript, we designed and fabricated a novel integrated microfluidic Kidney Nephron-On-Chip. This chip is able to culture cell monolayers under various fluid shear stresses and divert osmotic pressure gradients while imposing four different concentrations of an injected drug on cells. The multi-layer platform consisting of two bubble-trappers to eliminate all unwanted bubbles from the system, a concentration gradient generator to generate four different concentrations of the injected drug, and a membrane-based cell culture chamber caple of providing renal cells with their in-vivo condition. Using colorimetric techniques, the bubble trapper ability was quantified at flow rates up to...
Article Middle East Conference on Biomedical Engineering, MECBME ; 17-20 February , 2014 , pp. 261-264 ; Sharif University of Technology
In this study, the polarization and navigation of neuronal cells was studied in response to quantified gradients of nerve growth factor (NGF). To accomplish this, a microfluidic device was designed and fabricated to generate stable concentration gradients of biomolecules in a cell culture chamber within a 3D microenvironment. Numerical simulation was implemented to optimize the device geometry for generating a uniform concentration gradient of NGF which was found to remain stable for multiple hours. Neural Stem/ Progenitor Cell (NSCs) migration and differentiation was studied within this microfluidic device in response to NGF concentration and within a 3D environment of collagen matrix....
Article Scientia Iranica ; Volume 23, Issue 1 , 2016 , Pages 260-267 ; 10263098 (ISSN) ; Shamloo, A ; Azimi, S ; Abeddoust, M ; Saidi, M.S ; Sharif University of Technology
Sharif University of Technology
A cell migration numerical simulation is presented to mimic the motility of endothelial cells subjected to the concentration gradients of a Forebrain embryoniccortical neuron Conditioned Medium (CM). This factor was previously shflown to induce the directional chemotaxis of endothelial cells with an over-expressed G protein coupled receptor 124 (GPR 124). A cell simulator program incorporates basic elements of the cell cytoskeleton, including membrane, nucleus and cytoskeleton. The developed 2D cell model is capable of responding to concentration gradients of biochemical factors by changing the cytoskeleton arrangement. Random walk force, cell drag force and cell inertial effects are also...
Article Journal of Micromechanics and Microengineering ; Volume 26, Issue 1 , November , 2015 ; 09601317 (ISSN) ; Amirifar, L ; Sharif University of Technology
Institute of Physics Publishing 2015
Microfluidic devices have received wide attention and shown great potential in the field of tissue engineering and regenerative medicine. Investigating cell response to various stimulations is much more accurate and comprehensive with the aid of microfluidic devices. In this study, we introduced a microfluidic device by which the matrix density as a mechanical property and the concentration profile of a biochemical factor as a chemical property could be altered. Our microfluidic device has a cell tank and a cell culture chamber to mimic both 2D to 3D and 3D to 3D migration of three types of cells. Fluid shear stress is negligible on the cells and a stable concentration gradient can be...
Article Micromachines ; Volume 7, Issue 8 , 2016 ; 2072666X (ISSN) ; Nikmaneshi, M. R ; Moghadas, H ; Kiyoumarsi Oskouei, A ; Rismanian, M ; Barisam, M ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
MDPI AG 2016
With a mortality rate over 580,000 per year, cancer is still one of the leading causes of death worldwide. However, the emerging field of microfluidics can potentially shed light on this puzzling disease. Unique characteristics of microfluidic chips (also known as micro-total analysis system) make them excellent candidates for biological applications. The ex vivo approach of tumor-on-a-chip is becoming an indispensable part of personalized medicine and can replace in vivo animal testing as well as conventional in vitro methods. In tumor-on-a-chip, the complex three-dimensional (3D) nature of malignant tumor is co-cultured on a microfluidic chip and high throughput screening tools to evaluate...
High content of boride-forming elements in in617 nickel-based superalloy enables short isothermal solidification time during transient liquid phase bonding, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 51, Issue 11 , 2020 , Pages 5715-5724 ; Ghasemi, A ; Pouranvari, M ; Sharif University of Technology
Isothermal solidification stage during transient liquid phase bonding is the key to preclude intermetallic phase formation during solidification of the liquid phase. The rate of isothermal solidification is controlled by solid-state diffusion. Therefore, the bonding time required to complete isothermal solidification is generally long. This paper reports a very short isothermal solidification time for transient liquid phase bonding of IN617 solid solution nickel-based superalloy using a boron-containing filler metal. A eutectic-free bond with limited grain growth in the base material with high shear strength is achievable by utilizing a short (i.e., 5 minutes) thermal bonding strategy. The...
The effect of brine salinity and oil components on dynamic IFT behavior of oil-brine during low salinity water flooding: Diffusion coefficient, EDL establishment time, and IFT reduction rate, Article Journal of Petroleum Science and Engineering ; Volume 196 , 2021 ; 09204105 (ISSN) ; Ayatollahi, S ; Fatemi, M ; Sharif University of Technology
Elsevier B.V 2021
Dynamic behavior of fluid-fluid interactions can potentially affect the performance of any enhanced oil recovery (EOR) process including low salinity water flooding. In this work, dynamic interfacial tension (IFT) of crude-oil/brine system is measured in a wide range of salinity of sea water (SW), from 50-time diluted sea water (SW50D) to 2-time concentrated sea water (SW2C). Contrary to the most of published IFT trends in the literature, for the system under investigation here, as the brine salinity increases the crude-oil/brine IFT reduces, which cannot be explained using the existing theories. The lack of a physical model to explain the observed phenomena was the motivation to develop a...
Evaluating near highway air pollutant levels and estimating emission factors: Case study of Tehran, Iran, Article Science of the Total Environment ; Volume 538 , December , 2015 , Pages 375-384 ; 00489697 (ISSN) ; Delavarrafiee, M ; Arhami, M ; Sharif University of Technology
A field sampling campaign was implemented to evaluate the variation in air pollutants levels near a highway in Tehran, Iran (Hemmat highway). The field measurements were used to estimate road link-based emission factors for average vehicle fleet. These factors were compared with results of an in tunnel measurement campaign (in Resalat tunnel). Roadside and in-tunnel measurements of carbon monoxide (CO) and size-fractionated particulate matter (PM) were conducted during the field campaign. The concentration gradient diagrams showed exponential decay, which represented a substantial decay, more than 50-80%, in air pollutants level in a distance between 100 and 150meters (m) of the highway. The...