Sharif Digital Repository

Microfluidics based systems could be useful for drug discovery as they allow for miniaturization and could potentially be run as multiple parallel cell based assays. Such miniaturization allows assays at single cell level and reduces the amount of test material needed, which, in the case of natural product extracts, simplifies the preparation. Thyme species extracts have been reported to show some promising anti-cancer effects. In the present work, we used a microfluidics based system to study the effects of Thymus kotschyanusm Boiss plant extract on two human breast cancer cells lines which are MDA-MB-231 and MCF-7. For better understanding a single cancer cell death mechanism and a flow... 

Nowadays, the importance of the blood particles separation is undeniable in medical fields and there are different sorts of separation methods accordingly. Acoustic cell separation is chosen in this paper. Also, numerical methods have been used to study the effect of geometrical factors on the separation of the particles before spending time and expenses in a trial and error manner experimentally. We have implemented a plenary finite-element-based simulation of separatingblood particles such as white blood cells and platelets in an acoustic field using standing surface acoustic waves. In this paper, unlike previous works in which the channel is rectangular; the channel is trapezoidal in... 

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... 

Recently, microfluidic paper-based analytical devices (μPADs) have outstripped polymeric microfluidic devices in the ease of fabrication and simplicity. Surface tension-based fluid motion in the paper's porous structure has made the paper a suitable substrate for multiple biological assays by directing fluid into multiple assay zones. The widespread assumption in most works for modeling wicking in a paper is that the paper is a combination of capillaries with the same diameter equal to the effective pore diameter. Although assuming paper as a bundle of capillaries gives a good insight into pressure force that drives the fluid inside the paper, there are some difficulties using the effective... 

Herein, some (modified) paper–based substrates were prepared and utilized as extractive phases in a microfluidic device and their extraction performances examined for analytes with different polarities. Reagents including hexadecyltrimethoxysilane (HDTMS), phenyltrimethoxysilane (PTES), (3-aminopropyl) triethoxysilane (APTES) and 3–(2,3–epoxypropoxy) propyltrimethoxysilane (EPPTMOS) were implemented for the modification process. Due to the induction of different silane functional groups, it was anticipated to have various interactions for the tested analytes. Eventually, the prepared paper sheets were used as extractive phases for solid–phase extraction within a microfluidic system. The... 

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... 

Droplet-based microfluidics technologies hold great attention in a wide range of applications, including chemical analysis, drug screening, and food industries. This work aimed to describe the effects of different physical properties of the two immiscible phases on droplet formation in a flow-focusing microfluidic device and determining proper flow rates to form a droplet within the desired size range. A numerical model was developed to solve the governing equations of two-phase flow and the results were validated with previous experimental results. The results demonstrate different types of droplet formation regimes from dripping to jetting and different production rates of droplets as a... 

Identifying tumor cells from a pool of other cells has always been an appealing topic for different purposes. The objective of this study is to discriminate circulating tumor cells (CTCs) from blood cells for diagnostic purposes in a novel microfluidic device using two active methods: magnetophoresis and dielectrophoresis. The most specific feature of this device is the differentiation of CTCs without labeling them in order to achieve a more reliable and less complicated method. This device was analyzed and evaluated using finite element method. Four cell lines are separated in this device containing red blood cells, platelets, white blood cells, and CTCs. Primarily, red blood cells and... 

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... 

Dielectrophoresis is a robust approach for manipulating bioparticles in microfluidic devices. In recent years, many groups have developed dielectrophoresis-based microfluidic systems for separation and concentration of various types of bioparticles, where the gradient of the electric field causes dielectrophoresis force acting on the suspended particles. Enhancing the gradient of the electric field with three-dimensional (3D) electrodes can significantly improve the efficiency of the system. Implementing planar electrodes in a 3D arrangement is a simple option to form a 3D-electrode configuration. This paper reports the development of a novel dielectrophoretic microfluidic system for... 

In this survey, a reliable and applicable Y–Y shaped micro–channel in a microfluidic device was designed and manufactured. A number of micro–scaled hedges were precisely fabricated inside the micro–channel to facilitate the immobilization of synthesized core–shell Fe3O4@SiO2 magnetic nanoparticles (MNPs), functionalized by triethoxyphenylsilane (TEPS) by sol-gel technique. Both sample and reagents were introduced into the microfluidic device by a syringe pump to perform the extraction and desorption steps. The functionalized MNPs were characterized by transmission electron microscopy, X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy. By adopting the strategy of... 

Chemical bioreactions are an important aspect of many recent microfluidic devices, and their applications in biomedical science have been growing worldwide. Droplet-based microreactors are among the attractive types of unit operations, which utilize droplets for enhancement in both mixing and chemical reactions. In the present study, a finite-volume-method (FVM) numerical investigation is conducted based on the volume-of-fluid (VOF) applying for the droplet-based flows. This multiphase computational modeling is used for the study of the chemical reaction and mixing phenomenon inside a serpentine microchannel and explores the effects of the aspect ratio (i.e., AR = height/width) of... 

Microfluidic systems are an interesting topic for investigation due to their wide-spreading applications. Nowadays, polymeric solutions are used mainly for the generation of microparticles in biomedical engineering, food, and pharmaceutical industries. Droplet-based microfluidic devices have proposed an extensive interest in many applications such as chemical/biological/nanomaterial preparation to understand deeply the droplet size and formation in microchannels. However, numerous experimental and numerical studies have been done for oil-water combination, polymeric solutions behavior in the presence of oil has not been investigated widely. Therefore, it is important to understand the... 

In this study, droplet generation in a T-junction fluidic channel device was studied by using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in the decrease in the size of the droplet with increasing the velocity ratios. In the shearing regime, the effectiveness of electrowetting on... 

Circulating tumor cells (CTCs) isolation from a blood sample plays an important role in cancer diagnosis and treatment. Microfluidics offers a great potential for cancer cell separation from the blood. Among the microfluidic-based methods for CTC separation, the inertial method as a passive method and magnetic method as an active method are two efficient well-established methods. Here, we investigated the combination of these two methods to separate CTCs from a blood sample in a single chip. Firstly, numerical simulations were performed to analyze the fluid flow within the proposed channel, and the particle trajectories within the inertial cell separation unit were investigated to... 

The separation of cancer cells from a heterogeneous biological sample such as blood plays a vital role in cancer study and future treatments. In this paper, we designed and investigated two microfluidic devices for cancer cell separation, including a serpentine inertial device and an integrated inertial-magnetophoretic device. Firstly, numerical modeling was carried out to study the fluid flow, particles’ trajectories in the inertial device. Then the device was fabricated using soft photolithography and suspension of two types of microparticles with the size of 10 and 15 µm were injected into the microchannel separately to investigate the particles’ trajectories and focusing behavior at... 

Cells docking inside microfluidic devices is effective in studying cell biology, cell-based biosensing, as well as drug screening. Furthermore, single cell and regularly cells docking inside the microstructure of microfluidic systems are advantageous in different analyses of single cells exposed to equal drug concentration and mechanical stimulus. In this study, we investigated bottom wall microgrooves with semicircular and rectangular geometries with different sizes which are suitable for single cell docking along the length of the microgroove in x-direction and numerous cells docking regularly in one line inside the microgroove in a 3D microchannel. We used computational fluid dynamics to... 

Cells docking inside microfluidic devices is effective in studying cell biology, cell-based biosensing, as well as drug screening. Furthermore, single cell and regularly cells docking inside the microstructure of microfluidic systems are advantageous in different analyses of single cells exposed to equal drug concentration and mechanical stimulus. In this study, we investigated bottom wall microgrooves with semicircular and rectangular geometries with different sizes which are suitable for single cell docking along the length of the microgroove in x-direction and numerous cells docking regularly in one line inside the microgroove in a 3D microchannel. We used computational fluid dynamics to... 

Researchers usually simplify their simulations by considering the Newtonian fluid assumption in microfluidic devices. However, it is essential to study the behavior of real non-Newtonian fluids in such systems. Moreover, using the external electric or magnetic fields in these systems can be very beneficial for manipulating the droplet size. This study considers the simulation of the process of non-Newtonian droplets’ formation under the influence of an external electric field. The novelty of this study is the use of a shear-thinning fluid as the droplet phase in this process, which has been less studied despite its numerous applications. The effects of an external electric field on this... 

Microfluidic experiments have found wide applications in medical sciences and engineering, such as cell separation and focusing. In the present study, focusing and separation of particles with different sizes and densities were investigated by designing inertial microfluidic devices. The microfluidic channel is designed by analyzing the induced forces on the particles. In the designing process, the objective was to focus and separate the particles in the shortest length of the channel with the lowest possible cycles and high efficiency. The simulation is then used for analyzing the two proposed geometries to evaluate their particle separation and focusing ability, named convergent and...