Browsing by Subject "Micro-fluidic devices"

Now showing 1 - 4 of 4

Open Access
Microfluidic device for synthesis of chitosan nanoparticles
(ASME, 2013) Çetin, Barbaros; Taze, Serdar; Asik, M.D.; Tuncel, S.A.
Chitosan nanoparticles have a biodegradable, biocompatible, non-toxic structure, and commonly used for drug delivery systems. In this paper, simulation of a microfluidic device for the synthesis of chitosan nanoparticle is presented. The flow filed together with the concentration field within the microchannel network is simulated using COMSOL Multiphysics® simulation environment. Different microchannel geometries are analyzed, and the mixing performance of these configurations are compared. As a result, a 3D design for a microfluidics platform which includes four channel each of which performs the synthesis in parallel is proposed. Future research directions regarding the fabrication of the microfluidic device and experimentation phase are addressed and discussed. Copyright © 2013 by ASME.
Open Access
Rapid fabrication of microfluidic PDMS devices from reusable PDMS molds using laser ablation
(Institute of Physics Publishing, 2016) Isiksacan, Z.; Guler, M. T.; Aydogdu, B.; Bilican, I.; Elbuken, C.
The conventional fabrication methods for microfluidic devices require cleanroom processes that are costly and time-consuming. We present a novel, facile, and low-cost method for rapid fabrication of polydimethylsiloxane (PDMS) molds and devices. The method consists of three main fabrication steps: female mold (FM), male mold (MM), and chip fabrication. We use a CO2 laser cutter to pattern a thin, spin-coated PDMS layer for FM fabrication. We then obtain reusable PDMS MM from the FM using PDMS/PDMS casting. Finally, a second casting step is used to replicate PDMS devices from the MM. Demolding of one PDMS layer from another is carried out without any potentially hazardous chemical surface treatment. We have successfully demonstrated that this novel method allows fabrication of microfluidic molds and devices with precise dimensions (thickness, width, length) using a single material, PDMS, which is very common across microfluidic laboratories. The whole process, from idea to device testing, can be completed in 1.5 h in a standard laboratory.
Open Access
A simple approach for the fabrication of 3D microelectrodes for impedimetric sensing
(Institute of Physics Publishing, 2015) Guler, M. T.; Bilican, I.; Agan, S.; Elbuken, C.
In this paper, we present a very simple method to fabricate three-dimensional (3D) microelectrodes integrated with microfluidic devices. We form the electrodes by etching a microwire placed across a microchannel. For precise control of the electrode spacing, we employ a hydrodynamic focusing microfluidic device and control the width of the etching solution stream. The focused widths of the etchant solution and the etching time determine the gap formed between the electrodes. Using the same microfluidic device, we can fabricate integrated 3D electrodes with different electrode gaps. We have demonstrated the functionality of these electrodes using an impedimetric particle counting setup. Using 3D microelectrodes with a diameter of 25 μm, we have detected 6 μm-diameter polystyrene beads in a buffer solution as well as erythrocytes in a PBS solution. We study the effect of electrode spacing on the signal-to-noise ratio of the impedance signal and we demonstrate that the smaller the electrode spacing the higher the signal obtained from a single microparticle. The sample stream is introduced to the system using the same hydrodynamic focusing device, which ensures the alignment of the sample in between the electrodes. Utilising a 3D hydrodynamic focusing approach, we force all the particles to go through the sensing region of the electrodes. This fabrication scheme not only provides a very low-cost and easy method for rapid prototyping, but which can also be used for applications requiring 3D electric field focused through a narrow section of the microchannel.
Open Access
Spiral microfluidics device for continuous flow PCR
(ASME, 2013) Salemmilani, Reza; Çetin, Barbaros
Polymerase-chain-Reaction (PCR) is a thermal cycling (repeated heating and cooling of PCR solution) process for DNA amplification. PCR is the key ingredient in many biomedical applications. One key feature for the success of the PCR is to control the temperature of the solution precisely at the desired temperature levels required for the PCR in a cyclic manner. Microfluidics offers a great advantage over conventional techniques since minute amounts of PCR solution can be heated and cooled with a high rate in a controlled manner. In this study, a microfluidic platform has been proposed for continuous-flow PCR. The microfluidic device consists of a spiral channel on a glass wafer with integrated chromium microheaters. Sub-micron thick microheaters are deposited beneath the micro-channels to facilitate localized heating. The microfluidic device is modeled using COMSOL MultiphysicsR . The fabrication procedure of the device is also discussed and future research directions are addressed. With its compact design, the proposed system can easily be coupled with an integrated microfluidic device to be used in biomedical applications. Copyright © 2013 by ASME.