Browsing by Subject "Electrophoresis"

Now showing 1 - 5 of 5

Open Access
DC-electrokinetic motion of colloidal cylinder(s) in the vicinity of a conducting wall
(Wiley-VCH Verlag GmbH & Co. KGaA, 2022-06) Atay, Atakan; Beşkök, A.; Çetin, Barbaros
The boundary effects on DC-electrokinetic behavior of colloidal cylinder(s) in the vicinity of a conducting wall is investigated through a computational model. The contribution of the hydrodynamic drag, gravity, electrokinetic (i.e., electrophoretic and dielectrophoretic), and colloidal forces (i.e., forces due to the electrical double layer and van der Waals interactions) are incorporated in the model. The contribution of electrokinetic and colloidal forces are included by introducing the resulting forces as an external force acting on the particle(s). The colloidal forces are implemented with the prescribed expressions from the literature, and the electrokinetic force is obtained by integrating the corresponding Maxwell stress tensor over the particles' surfaces. The electrokinetic slip-velocity together with the thin electrical double layer assumption is applied on the surfaces. The position and velocity of the particles and the resulting electric and flow fields are obtained and the physical insight for the behavior of the colloidal cylinders are discussed in conjunction with the experimental observations in the literature.
Open Access
Identification of relative protein bands in Polyacrylamide Gel Electrophoresis (PAGE) using multiresolution snake algorithm
(IEEE, 1998-10) Gürcan, Metin Nafi; Koyutürk, Mehmet; Yıldız, H. Serkan; Çetin Atalay, Rengül; Çetin, A. Enis
Polyacrylamide Gel Electrophoresis (PAGE) is one of the most widely used techniques in protein research. In the protein purification process, it is important to determine the efficiency of each purification step in terms of percentage of protein of interest found in the protein mixture. This study provides a rapid and reliable way to determine this percentage. The region of interest containing the protein is detected using the snake algorithm. The iterative snake algorithm is implemented in a multiresolutional framework. The snake is initialized on a low resolution image. Then, the final position of the snake at low resolution is used as the initial position in the higher resolution image. Finally, tile area of the protein is estimated as the area enclosed by the final position of the snake.
Open Access
An integrated acoustic and dielectrophoretic particle manipulation in a microfluidic device for particle wash and separation fabricated by mechanical machining
(American Institute of Physics Inc., 2016) Çetin B.; Özer, M. B.; Çağatay, E.; Büyükkoçak S.
In this study, acoustophoresis and dielectrophoresis are utilized in an integrated manner to combine the two different operations on a single polydimethylsiloxane (PDMS) chip in sequential manner, namely, particle wash (buffer exchange) and particle separation. In the washing step, particles are washed with buffer solution with low conductivity for dielectrophoretic based separation to avoid the adverse effects of Joule heating. Acoustic waves generated by piezoelectric material are utilized for washing, which creates standing waves along the whole width of the channel. Coupled electro-mechanical acoustic 3D multi-physics analysis showed that the position and orientation of the piezoelectric actuators are critical for successful operation. A unique mold is designed for the precise alignment of the piezoelectric materials and 3D side-wall electrodes for a highly reproducible fabrication. To achieve the throughput matching of acoustophoresis and dielectrophoresis in the integration, 3D side-wall electrodes are used. The integrated device is fabricated by PDMS molding. The mold of the integrated device is fabricated using high-precision mechanical machining. With a unique mold design, the placements of the two piezoelectric materials and the 3D sidewall electrodes are accomplished during the molding process. It is shown that the proposed device can handle the wash and dielectrophoretic separation successfully. © 2016 AIP Publishing LLC.
Open Access
On-chip integrated nanowire devices with controllable nanogap for manipulation, capturing, and electrical characterization of nanoparticles
(IEEE, 2009) Uran, Can; Ünal, Emre; Kizil, R.; Demir, Hilmi Volkan
Dielectrophoresis (DEP) allows for electric field assisted assembly in spatially non-uniform field distribution, where the induced moment is translated into a net force on polarized particles towards the high field gradient. For example, for a spherical particle of radius r with a permittivity constant ofεp in a host medium with the permittivity ofε m, the dielectrophoretic force is given by (1): where r is the particle radius, ω is the angular frequency and Erms is the root mean square electric field. K is the Clausius-Mossotti function, which depends on the complex permittivity of the spherical particle and the medium [1].IEEE.
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.