Sharif Digital Repository

The recent breakthroughs in the lab-on-a-chip technology will not be directly used as clinical devices unless the specific applications are carefully tested and certified. As there is a growing trend towards microfluidic devices for biomedical research, an active microfluidic device was developed. Common microfabrication methods were used to develop a microchip to separate and concentrate exosome and particular cell based on the dielectrophoresis phenomenon. Unique capabilities of the dielectrophoresis phenomenon make it a powerful tool for micro particle manipulation in micro scale. In this research, geometry for the mentioned purpose is designed and optimized. Three-dimensional... 

Polymerase Chain Reaction (PCR) is a process in which a special piece of a gene is amplified millions of times over a short period. This method has been of paramount importance in different fields of research and has been applied for different applications. PCR requires thermal cycling, or repeated temperature changes between two or three discrete temperatures to amplify specific nucleic acid target sequences. To achieve such thermal cycling, conventional bench-top thermal cyclers generally use a metal heating block powered by Peltier elements or benefit from forced convection heat transfer. Due to the fact that these methods are time consuming, it seems that design and fabrication of a fast... 

Microfluidics is an emerging technology that has attracted lots of attention in recent years due to its remarkable capabilities. This technology that operates fluids in micron dimensions, has led to the emergence of lab-on-a-chip platforms that have the ability to perform one or more laboratory operations on a small scale. One of the most important applications of lab-on-a-chip devices is cell sorting which is done in various methods. In this study, we intend to provide a simple and practical solution for cell sorting by designing a comprehensive and optimized system. In this regard, we design a new generation of microfluidic devices, known as digital microfluidics, which has the ability to... 

Cancer is the second leading cause of death among humans as one of the major human concerns. More than 500,000 people die of cancer each year in the United States alone. Cancer mortality is mainly due to cancer metastasis. Metastasis is the escape of cancer cells from a primary tumor, the circulation of cells in the circulatory system (CTSs), the penetration of/from vessel wall, and the formation of a secondary tumor. It is still not clear how the cells survive in the circulatory system, along with the mechanical pressures and stresses that exist in the body's capillary channals. In this study, a microcirculation model for circulating cells with barriers was designed and constructed by the... 

Cancer is an abnormal growth of cells which is one of the major cause of worldwide’s mortality. Circulating Tumor Cells (CTCs) are rare cancer cells released from the primary or metastatic tumors and transported though the peripheral circulatory system and spreads in body and seize healthy organs. Early detection of CTCs can help in overtaking the cancer, hence isolation of CTCs is an essential step for many therapeutics. 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), similarity to white blood cell in size and also variability in terms of... 

Isolation and characterization of circulating tumor cells (CTCs) found in blood samples of cancer patients have been considered as a reliable source for cancer prognosis and diagnosis. A new continuous microfluidic platform has been designed in this investigation for simultaneous capture and characterization of CTCs based on their deformability. The deformability-based chip (D-Chip) consists of two sections of separation and characterization where slanted weirs with a gap of 7 μm were considered. Although sometimes CTCs and leukocytes have the same size, the deformability differs in such a way that can be exploited for enrichment purposes. MCF7 and MDA-MB-231 cell lines were used for the... 

Based on numerous laboratory and field evidence, low-salinity waterflooding or engineered salinity waterflooding can lead to enhanced oil production. According to the literature, the mechanisms involved in this process can be divided into two general categories: fluid-fluid interactions and solid-liquid interactions. These mechanisms are caused by intermolecular and electrostatic forces at the rock and fluid interfaces. The most important controlling factor of the electrostatic forces is the concentration of ions at/near fluids-rock interface. Therefore, improving the concentration of ions causes a shift in wettability toward a more water-wetting state, eventually leading to increased oil... 

Today, the determination and therapy of numerous illnesses, including malignant growth, relies upon the information and assessment of platelets, so blood testing and cell examination is fundamental to survey the movement of disease. The lab on a chip innovation is utilized as an extremely productive device in cell studies. The lab on a chip is used as a foundation and a substrate for making a legitimate stream for cell processes in medication. This innovation is a gadget or framework with millimeters or centimeters aspects like a chip, and it performs research facility handling on a micron-scale. In spite of the fact that it has a few impediments, it has so many values; for example, it... 

Microfluidics is the science of fabricating systems interfacing fluids of small volume and size ranging from microliters (10-6) to picolitres (10-12). Due to its remarkable features, such as low sample and reagent consumption, high sensitivity, low cost, automated devices, and short experimental time, microfluidic chips have been widely used as laboratory assays. As a term often used and described in “lab on a chip” and “organ on a chip” technologies, microfluidic chips have been used in the fast and frugal diagnosis of infectious diseases such as HIV, microscale surgery on single cells and tiny organisms and cell culture.The design, simulation, optimization, and fabrication of an... 

Emulsions are the intermittent dispersion of liquid droplets that have many applications such as polymerization, dyeing, cosmetics, food industry, etc. Droplets can be created in a variety of ways, but the most important point in emulsification and the greatest efficiency of its applications is when the formed droplets are uniform. In the emulsification process, there is a key parameter called interfacial tension, which affects the behavior of the formed droplets, such as their stability and morphology, and its precise measurement is very effective in the quality control of the mentioned applications. Be. In this research, droplet formation in microfluidic systems due to uniform droplet... 

Microfluidic technology is a field of science that deals with the design, implementation, optimization, and testing of fluid systems in small dimensions. This technology has made significant progress in various fields in the last decade, especially in medical engineering. As an interdisciplinary scientific field, this growing technology has many applications in medicine, pharmaceuticals, chemistry, and electronic industries. One of the primary applications of microfluidic devices is the development of "lab-on-a-chip" systems as point-of-care diagnostic tools, such as rapid diagnosis during surgery. A microfluidic system includes various functional modules: sample preparation and fluid... 

Droplet-based microfluidic logic gates have many applications in diagnostic tests and biosciences due to their automation and cascading ability. Although most biological fluids, such as blood, exhibit non-Newtonian properties, all previous studies in this field have been with Newtonian fluids. Additionally, none of the previous work has studied the functional area of logic gates. In the present work, AND-OR logic gate with power-law fluid is considered. The effect of important parameters such as non-Newtonian fluid properties, droplet length, capillary number, and geometrical properties of the microfluidic system on the operating region of the system has been investigated. The results show... 

Hydrogen storage in porous subsurface formations, such as aquifers or depleted hydrocarbon reservoirs because of their high storage capacity, has gained momentum as a promising approach to balance the renewable energy supply and demand. However, the poor understanding of hydrogen flow dynamics in porous media is the main obstacle to the development and widespread application of underground hydrogen storage (UHS). For example, the main uncertainty is lack of detailed understanding of hydrogen flow dynamics in the natural porous media which leads to the unknown volume of recoverable hydrogen for this cyclic process. In this research, by developing a visual microfluidic apparatus to handle... 

Manufacturing in many industries, such as electronics, petrochemical, automotive, and food, has long relied on continuous approaches, while the pharmaceutical industry has traditionally been processed in batch reactors. Since the beginning of the third millennium, continuous drug synthesis has received attention due to its multiple advantages over batch systems, which include process safety, adaptability, controllability, economic efficiency, scale-up, and enhancing performance. In this project, the pharmaceutical intermediate 1,4-benzodiazepine, which is usable as a precursor of diazepam and flurazepam, is continuously synthesized in a 400 microliters integrated micromixer and microreactor... 

In this study, the performance of electrocoalescence in a microfluidic device was investigated through numerical simulations. The microfluidic device consisted of two immiscible fluids, a continuous phase, and a dispersed phase, which were modeled as incompressible Newtonian fluids. The interface between the two phases was tracked using a phase-field model. A flow-focusing geometry was employed to crate water droplets in oil. The dispersed droplets were then pass over a set of electrodes. The merging of two adjacent droplets in the microfluidic device was observed by applying a constant electric field. The voltage of 60 V is the lowest voltage at which the regular merging of pairs of drops... 

In this project a centrifugal, microfluidic platform to the end of separation and studying circulating tumor cells is designed, modelled and analyzed. Circulating tumor cells (CTCs) are specific types of cancer cells which leave the original tumor and enter the blood stream. For the separation of CTCs, a novel anti-body separation technic has been used which targets the specific MCF7 CTCs using their corresponding Ep-CAM antibody. First the Ep-CAM antibody is coated on magnetic nanoparticles through a chemical bonding process. Afterwards the CTCs are exposed to their antibodies, through which they will bind together and form CTCs with magnetic characteristics. Finally through exerting an... 

Particle separation has a variety of applications in biology, chemistry and industry. Among them, circulating tumor cells (CTCs) separation has drawn significant attention to itself due to its high impact on both cancer diagnosis and therapeutics. In recent years, there has been growing interest in using inertial microfluidics to separate micro/nano particles based on their sizes. This technique offers label-free, high throughput, and efficient separation and can be easily fabricated. However, further improvements are needed for potential clinical applications. In this study, a novel inertial separation technique using spiral microchannel with stair-like cross section is introduced. The... 

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... 

Circulating tumor cells (CTCs) isolation from a blood sample has an important value in cancer research and its treatment. Microfluidics provides a great potential for target cell separation from biological samples by using different physical principles. Among the microfluidic cell separation methods, the inertial microfluidic devices are advantageous in handling samples for point-of-care diagnostics due to their simple structure, fast, label-free and low-cost characteristics. In this thesis, first, we designed and investigated the application of a symmetric serpentine inertial microfluidic device for the separation of CTCs from whole blood. For this purpose, numerical modeling was performed... 

Nowadays, advanced and inexpensive pre-clinical methods for investigating the effects of anti-cancer drugs are expanding. One of the latest three-dimensional laboratory modeling for evaluating the effects of drugs is the use of tumor-on-chip technology, which actually models the physiological system of the body through three-dimensional scaffolds, multicellular cultures, and shaped vascular systems. In this study, three-dimensional culture of cancer cells was performed in the form of spheroids. A chip of U-shaped microstructures with and without gaps was used to trap cells and form cancer spheroids. We simulated the simultaneous effect of drug and oxygen concentration distribution inside the...