Sharif Digital Repository

A bioreactor can refer to any device or system constructed on engineering basis and has an active biological medium. This medium includes aerobic and non-aerobic reactions in which organisms and the theire produced substances have the main role. One of the applications of bioreactors is to provide an appropriate medium for animal and plant cell culture and growth. Nowadays many biological processes in high volume scales are carried out in stirred tank bioreactors. In these bioreactors oxygen transfer is usually increased by increasing turbulence which is necessary for mixing nutrients and keeping the homogeneity of the medium. However, there are some limitations for increasing the stirring... 

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... 

Aerosols are significant two-phase systems that have an important effect on environmental, biological, health, industrial and other scientific and engineering fields. According to chief aerosol effects, various instruments namely “Aerosol Spectrometer” have been developed to measure aerosols. Optical Particle Counters (OPCs) are one of this instruments that can count and measure the particles size distribution in the aerosols.
In the current project, an optical particle counter has been designed. For validating the correct operation of the designed plan, it is needed to simulate the instrument optically and mechanically, so the Mie theory was used to simulate the intensity of the... 

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... 

The urine formation and excretion system has long been of interest for mathematicians and physiologists to elucidate the obscurities within the process happen in renal tissue. In this study, a novel and absolutely three-dimensional approach is utilized for modeling urine concentrating mechanism in rat renal outer medulla which is essentially focused on demonstrating the significance of tubule's architecture revealed in anatomic studies and physiological literature. Since nephrons and vasculatures work interdependently through a highly structured arrangement in outer medulla which is dominated by vascular bundles, a highly detailed functional unit is proposed and also it is strongly justified... 

In the present thesis, intracellular fluid flows have investigated for study cell motions. It is due to firmly relation between the cell motion and these flows. Generally, the cell firstly adheres to a surface, then, moves forward with the effects of the internal fluid flows. In this study, the cell structure is invided to two general parts; the front part of the cell and the cell body. The front part of the cell plays a essential roles in the cell motion, however, the cell body is considered as a extra cargo that is carried by the front of the cell. Therefor, in the present modellings, the front part is only considered. Here, using four different models for the front part of the cell, many... 

In this dissertation, mass transport in cardiovascular system has been simulated using one-dimensional approach. As one-dimensional simulation has computation cost less than that of the three-dimensional simulations, and as it is more precise than lumped models, they are extensively used in the study of the phenomena in cardiovascular system. In addition, such an approach is more useful in the extraction of medical indices. In this study, a one-dimensional geometry of the systemic arteries has been used to solve momentum and continuity equations using characteristics method.
At first, the physiological data of the systemic arteries have been used to simulate a one-dimensional geometry... 

Insulin pump treatment is considered the most physiological way to imitate the healthy body's insulin profile in patients with diabetes. They provide a precisely controlled rate of insulin delivery to diabetic patients who would normally need multiple daily injections to regulate blood glucose levels. The firmware allows numerous modifications to the bolus dose and basal rate to enable patients to manage insulin levels in response to events such as eating, sleeping, and exercise.
In this Study, we have first investigated different models of insulin pumps on the market and chose the Spring ZoneTM insulin pump model for our study due to its innovative technology. This pump employs a... 

Single ventricle anomaly is a congenital heart disease which is characterized by anatomical malformations. The main abnormality that a patient faces is desaturated blood flow, which, without any treatment increases the risk of death. The classical treatment is based on a three stage palliative procedure which should begin from the first few days of patient’s life. The final stage is known as Fontan procedure which directly connects inferior vena-cava to pulmonary arteries without going through the ventricle.This connection is known as Total Cavo Pulmonary Connection (TCPC). After surgery, the single ventricle could supply adequate and saturated systemic blood flow for the body, but TCPC... 

In this thesis, hemodynamic parameters of flow and deposition of low density lipoproteins (LDL) on wall of coronary arteries with taking into account their curvature on the heart are studied. At first, numerical solution of the blood flow by assumption of blood as incompressible and Newtonian fluid for steady and pulsatile inlet is done. Then by assuming LDL particles as dilute solute in the blood, LDL transport from artery lumen into arterial wall is studied. LDL accumulation and penetration into the vessel wall cause thickening of the walls and eventually eclipse it and its known as the first stage of atherosclerosis disease. The results show that low shear region occurs on inner wall... 

According to statistics in 2012, around 14 million people worldwide have cancer, and 8 million have died that year, according to estimates, this number will increase to 21 millions new cancer case and 13 million mortality in 2030. Despite years of research on cancer, many questions about the mechanism of the spread of cancer in the body remain unanswered so far. The proposed models identify that the cells isolated from the primary tumor and transmit them to the circulatory system in the form of circulating tumor cells (CTCs) or in the form of clusters as responsible for the incidence of cancer. This process is called metastasis. Recent studies have reported the high potential of metastasis... 

Micro-Robotics is implemented by researchers inclusively in last decades in different fields such as, biolotechnology, space, army and medical engineering. However, micropositioning is the main challenge in such projects, since determination and control of micro-robot’s position for drug delivery, artificial insemination and other medical applications are too significant. In this thesis, a method for controlling a microswimmer’s position in two dimention by an external magnetic field has been proposed. Modelling of magnetic field and magnetic gradient are some important challenges due to the fact that in control loop, a fast and optimal model for estimation of magnetic filed and gradient is... 

Investigation of the behavior of living cells in different biological conditions could play a key role in exploring the main reasons of humans' disorders and diseases. In this regard, many researchers are studying different subjects related to the living cells. Although most of these research activities are based on experimental methods, numerical approach could be utilized to investigate some topics which cannot be studied by experimental methods.In this study a three dimensional model of endothelial cell is proposed for the investigation of cell performance during compression test. The model consists of cell membrane, nucleus and main components of cytoskeleton, namely actin filaments,... 

Nowadays cell-based microfluidic devices have many applications. One of the applications is disease diagnosis according to number of cells. Cell counting has different methods, such as optical cell counting, flow cytometry, hemocytometry, coulter counters,and so on. One of the methods of cells counting is based on measurement of changes in impedance or conductivity of surrounding medium because ions are released from surface-immobilized cells inside a micr of luidic channel.The method of cell lysate impedance spectroscopy is sensitive enough and it was offered for detecting and enumerating CD4+ cells in HIV patients. In this study,... 

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... 

Particulate air pollution is one of the top environmental health risks. Industrial processes like power generation from fossil fuels and steel and cement manufacturing release a huge amount of particles into the atmosphere. Moreover, internal combustion engines produce a considerable amount of particulate matter in populated areas. The usual way to overcome this risk is using air-cleaning devices such as filters. Filters are designed for specific purposes like removing aerosol particles, aerosol sampling and collecting valuable particles. Because of its diverse applications, filtration has become an active area of research and many kinds of filters are currently available. One type of... 

With the increasing development of the pharmaceutical industry and producing drugs with specific performance, its transfer into cells is also very important. Cell membranes are effectively impermeable to hydrophilic compounds unless the permeation is facilitated by dedicated transport systems. This means that many hydrophilic compounds, including many promising drug candidates, fail to reach their intracellular target because they cannot spontaneously cross lipid membranes. As a consequence, there is much interest in finding ways to facilitate the transport of molecules across cell membranes. Cell-penetrating peptides (CPPs) in particular have shown much promise as potential delivery agents... 

It is known today that arterial diseases are among the leading cause of death in modern societies. More than 50% of deaths in western countries are mainly occurred as results of these diseases, namely atherosclerosis. In order to study risk factors and to understand the full process of how arterial diseases initiate and progress, many research topics have been introduced and studied. Researchers believe that mechanical factors such as Wall Shear Stress (WSS), Pressure distribution, Cyclic strain, Back flow zones and many other factors are responsible for initiation of atherosclerosis. Different patterns of Wall Shear Stress and Strain are seen in arteries. Among other factors outlined in... 

In this paper, a one-dimensional and two-dimensional numerical approach is used to study the effect of various parameters such as micro combustor height, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system (A-D-R) that leads to two stiff systems of PDEs, which can not be solved by conventional Computational Fluid Dynamics (CFD) methods. In the present work, Strang splitting method, which is suitable for nonlinear stiff... 

In this project, two Ferrofluidic micropumps that do not need any mechanical moving parts are presented. These micropumps are including simple microchannels containing magnetic fluid plugs that are used as flow actuator and the on/off valve. Using external magnetic field actuation in this type of micropumps, the magnetic fluid would have continuous motion in a channel with micrometer dimensions that would provide the main fluid to be pumped. Although the plug of magnetic fluid has surface contact with operative fluid, but considering its specific features, it would not compine with the pumping fluid. These micropumps may be used to pump the fluids or gases. The outcomes of the investigation...