Browsing by Author "Zeinali, Soheila"

Now showing 1 - 4 of 4

Open Access
Magnetic pumps
(Springer, 2015) Çetin, Barbaros; Zeinali, Soheila; Li, D.; Li, D.
Micropumps can be classified into two general categories: mechanical and nonmechanical micropumps (an excellent review on micropumps can be found elsewhere [1]). In a typical mechanical pump, a membrane is used to produce the pumping action. Nonmechanical micropumps on the other hand generally have no moving parts. Common mechanical micropumps fall into three categories based on the mechanical action used: check valve, peristaltic, and rotary pumps. They can also be categorized according to their actuation method: pneumatic, piezoelectric, external electric motor, or magnetic field. Among these actuation techniques, magnetic field actuation has shown promise for research purposes at micro- and nanoscales because of creating smooth fluid flow. Magnetic pumps can be found in both categories, mechanical, and nonmechanical in the literature.
Open Access
Microfluidic device with 3D electrode structure for high throughput dielectrophoretic applications
(2014-10) Zeinali, Soheila
Microfluidics is the combination of micro/nano fabrication techniques together with knowledge of fluid behavior at the microscopic level to pursue powerful techniques in controlling, manipulating and measuring chemical, physical and biological processes at micro/nano scale. Sorting and separation of bio-particles are highly considered in diagnostics and biological analyses. By implementing the characteristics of microscale flow phenomenon, dielectrophoresis (DEP) has offered unique advantages for microfluidic devices. In DEP devices asymmetric pair of planar or three dimensional (3D) electrodes could be employed to generate non-uniform electric field. In DEP applications, facing 3D sidewall electrodes is considered to be the key solution of increasing device throughput because of producing homogeneous electric fields along the height of microchannels. Despite all advantages, fabrication of 3D vertical electrodes requires considerable challenge. In this thesis, in order to highlight the advantage of 3D electrodes over planar electrodes, the simulations are performed. Based on the developed computational model, the design parameters are decided. For the fabrication of the device, two different fabrication techniques have been proposed. In the first method, both the mold and the electrodes are fabricated using high precision machining. In the second method, the mold is fabricated with tilted sidewalls using high precision machining and the electrodes are deposited on the sidewall using sputtering together with a shadow mask fabricated using wire electric discharge machining (WEDM). The both techniques are assessed as highly repeatable and robust methods. Only the manipulation of particles with negative-DEP has been demonstrated in the experiments, and the throughput values up to 105 particles/min have been reached in a continuous flow.
Open Access
Microfluidic optical devices
(Springer, 2015) Çetin, Barbaros; Zeinali, Soheila; Li, D.; Li, D.
Microfluidic optical devices (MOD) are the emerging technology that combines today’s microfluidics technology with the optics. However, MOD can be classified as the integration of these two technologies rather than combination of them. This integration provides a new approach for using microfluidics for control and manipulation of samples and optics for sensing. In this entry we propose a comprehensive review of emerging applications for microfluidic optical devices.
Open Access
Simulation of an integrated microfluidic device for bioparticle wash, separation and concentration
(American Society of Mechanical Engineers (ASME), 2013) Çetin, Barbaros; Büyükkoçak, S.; Zeinali, Soheila; Özer, B.
Washing, separation and concentration of bioparticles are key operations for many biological and chemical analyses. In this study, the simulation of an integrated microfluidic device is studied. The proposed device has the capability to wash the bioparticles (transferring the bioparticles from one buffer solution to another), to separate the particles based on their dielectric properties and to concentrate the bioparticles. Washing and concentration of bioparticles are performed by acoustophoresis and the separation is performed by dielectrophoresis. For simulating the flow within the microchannel, a computational fluid dynamics model using COMSOL Multiphysics software is implemented. In order to simulate the particle trajectories under ultrasonic and electric field, point-particle assumption is chosen using MATLAB software. To account for the size variation of the bioparticles, particles with normal size distributions are used in-side the microchannel. The effect of the key design parameters such as flow rate, applied voltage etc. on the performance of the device is discussed. Copyright © 2013 by ASME.