Sharif Digital Repository

Design, simulation, optimization and manufacturing of an enzyme-based microfluidic biosensor has been carried out during this research to measure histamine concentration in a sample. The designed biosensor is composed of a micro-bioreactor to degrade histamine and yield hydrogen peroxide, and a chemical reactor to measure the amount of hydrogen peroxide, using chemiluminescence methods. The geometry of the bioreactor and chemical reactor is developed through comparison and optimization of several different geometries. In theory, the designed sensor can determine histamine concentration in a range of 10M to 1mM under one minute, with a maximum error of 5%. Designed biosensor is built using... 

The advent of microfluidics as suitable environments for culturing cells is associated with some challenges such as shear stresses applied on the cells. In fact, hepatocytes lose their function as exposed to high shear stresses similar to other cell types. Moreover, among all factors needed for cell viability, feeding hepatocytes with adequate oxygen is of great importance due to their high demand for oxygen compared the other cells. In this thesis, different types of cultures including 2D and 3D has been used in order that shear stresses would be in allowed range and provision of hepatocytes with sufficient oxygen concentrations has been ensured as well. In addition to supplying hepatocytes... 

Lab-on-a-chip devices have gained a lot of attention in chemical and biomedical analyses during the past two decades. These devices employ microfluidics basics and fundamentals to combine multifold laboratory processes in one single portable chip. The electric field has been often used in most microfluidics applications for the ease of sample control as well as become easily integrated to other chip components. Instabilities in microflows would occur when two fluids of different electric properties are exposed to an adequately strong electric field. Studying these electrokinetic instabilities is not only important for the fundamental studies but also for practical applications in micromixers... 

Due to the increasing need of use of drugs and insufficient efficiency of conventional methods, drug delivery systems has gathered a lot of interests. There are different systems existing for controlled drug delivery, among which is implementation of hydrogel microparticles (microgels) as carriers with high potential. The most important factor in these systems is size distribution of drug-carrying microgels and a narrow size distribution leads to a controlled and suitable release. Due to unique characteristics of microfluidic systems, significant focus has been placed on them nowadays for production of microgels with suitable morphology and narrow size distribution. Therefore, in this study... 

The main goals of this research are design, simulation, and fabrication of a microfluidic system working based on dielectrophoresis. This research divided into two different parts, the first of which is the simulation of a microfluidic system, and second of which is an attempt for fabrication of microfluidic system. For the fabrication of the microfluidic system, different methods were used. In the simulation part, the enrichment of different particles was investigated, and the effects of different parameters on the enrichment were assessed. It was observed that as flow rate increases, the enrichment amount diminishes. Furthermore, as the microfluidic depth decreases, the enrichment amount... 

Recent developments in MEMS related areas have increased the demand for practical and novel pumping methods. Utilizing Electroosmotic force for flow generation in microchannels has become really popular recently, because of its reliable operation and control. One of potential applications of MEMS devices is biological and medical analysis which most samples are considered to be non-Newtonian; consequently, thermal transport characteristics of non-Newtonian electroosmotic flow of power-law fluids is investigated in this paper. In this study, thermal and hydrodynamic behavior of non-Newtonian electroosmotic flow of power-law model in a slit microchannel is analyzed. It is assumed that the flow... 

Electroosmosis is the predominant mechanism for flow generation in lab-on-a-chip devices. These microfluidic devices are microscale laboratories on a microchip that can perform clinical diagnoses. Since most biofluids encountered in these devices are considered to be non-Newtonian and the cross section of microchannels in these devices is close to a rectangular shape, In this study, the hydrodynamically and thermally fully developed combined electroosmotically and pressure driven flow of power-law fluids in rectangular microchannels is analyzed. The governing equations are first made dimensionless and then transformed into new ones based on the computational parameters which provide mesh... 

The lab-on-a-chip (LOC) devices utilizing electroosmosis for flow actuation are usually encountered with non-Newtonian behavior of working fluids. Hence, studying the flow of non-Newtonian fluids under an electroosmotic body force is of high importance for accurate design and active control of these devices. In this thesis, mixed electroosmotically and pressure driven flow of salivathrough a rectangular microchannel is examined utilizing two viscoelastic constitutive equations, namely PTT and FENE-P models. Since the hydrodynamic entry length is usually negligible for microflows, a hydrodynamically developed flow is considered in the analysis. The governing equations in dimensionless form... 

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...