Ozkan, Alican
Keleştemur, Yusuf
Demir, Hilmi Volkan
Erdem, E. Yegan
We present a microfluidic reactor that utilizes meandering microchannel shape to mix reagents inside droplets in a carrier fluid to synthesize silica and silica coated nanoparticles. Meandering channels decrease mixing time due to reduced diffusion lengths. Moreover; droplet-based flow provides uniform reaction times due to the circulating flow profile inside droplets as opposed to parabolic flow profile in straight channels. Before fabricating our device, we have simulated the mixing performance of droplets at different channel cross-sections and meandering geometries using Comsol Multiphysics(C). As a result, we have concluded that channel cross-section and meandering dimensions should be as small as possible for faster mixing. Accordingly, we have fabricated our device in PDMS by using soft lithography technique and introduced chemicals to the microsystem by using syringe pumps. We will use this system to understand the effect of solvent concentration and residence time on silica formation to obtain better coating thickness distribution than in batch-wise methods. As a preliminary study, we tested the silica formation inside droplets and we obtained 102 nm 4 nm of silica nanoparticles. In the synthesis we followed a modified method of synthesis in the literature where droplets of solution composed of 20 mL Cyclohexane, 2.6 mL IGEPAL and 300 mu L TEOS were formed inside the carrier fluid NH4OH at a flow rate ratio of 2:1. It is observed that nanoparticles were synthesized as a result of diffusion and mixing of NH4OH inside droplets. Currently, we are working on introducing QDs in droplets and coating them with silica shells inside the microreactor. We will also study the effects of NH4OH concentration, residence time on silica shell thickness and com
13TH ASME International Conference on Nanochannels, Microchannels, and Minichannels


Nikdoost, Arsalan; Ozkan, Alican; Keleştemur, Yusuf; Demir, Hilmi Volkan; Erdem, E. Yegan (2017-01-01)
This paper describes a method for the synthesis of silica nanoparticles that can be later used for coating of quantum dots inside a microfluidic reactor. Here, a droplet-based system is used where two reagents were mixed inside the droplets to obtain silica. Particles in the size range of 25 +/- 2.7 nm were obtained with comparable size distribution to controlled batch wise synthesis methods. This method is suitable to be used later to coat CdSe nanoparticles inside the microreactor.
Hydrothermal synthesis of TiO₂ nanostructures for photocatalitic and photovoltaic applications
Erdoğan, Nursev; Öztürk, Abdullah; Park, Jongee; Department of Metallurgical and Materials Engineering (2017)
Titanium dioxide (TiO2) nanostructures with different crystal structures and various morphologies were synthesized by hydrothermal process to utilize them in photocatalytic and photovoltaic applications. The investigations were conducted in three different sets of systematic experimental studies. The first set of experiments was based on the synthesis of TiO2 nanostructures in the presence of strong sodium hydroxide (NaOH) catalyzer. Temperature and molarity of NaOH were kept constant while hydrothermal rea...
Colloid-in-Liquid Crystal Gels that Respond to Biomolecular Interactions
Agarwal, Ankit; Sidiq, Sumyra; Setia, Shilpa; Büküşoğlu, Emre; de Pablo, Juan Jose; Pal, Santanu Kumar; Abbott, Nicholas L (Wiley, 2013-08-26)
This paper advances the design of stimuli-responsive materials based on colloidal particles dispersed in liquid crystals (LCs). Specifically, thin films of colloid-in-liquid crystal (CLC) gels undergo easily visualized ordering transitions in response to reversible and irreversible (enzymatic) biomolecular interactions occurring at the aqueous interfaces of the gels. In particular, LC ordering transitions can propagate across the entire thickness of the gels. However, confinement of the LC to small domains ...
Thermal stimulation of aqueous volumes contained in carbon nanotubes: Experiment and modeling
Yarin, AL; Güvenç Yazıcıoğlu, Almıla; Megaridis, CM (2005-01-01)
The dynamic response, as caused by thermal stimulation, of aqueous liquid attoliter volumes contained inside multiwall carbon nanotubes is investigated theoretically and experimentally. The experiments indicate an energetically driven mechanism responsible for the dynamic multiphase fluid behavior visualized under high resolution in the transmission electron microscope. The theoretical model is formulated using a continuum approach, which combines temperature-dependent diffusion with intermolecular interact...
Vacuum-processed polyethylene as a dielectric for low operating voltage organic field effect transistors
Kanbur, Yasin; Irimia-Vladu, Mihai; Glowacki, Eric D.; Voss, Gundula; Baumgartner, Melanie; Schwabegger, Guenther; Leonat, Lucia; Ullah, Mujeeb; Sarica, Hizir; ERTEN ELA, ŞULE; Schwoediauer, Reinhard; Sitter, Helmut; Kucukyavuz, Zuhal; Bauer, Siegfried; Sariciftci, Niyazi Serdar (2012-05-01)
We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C-60 as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm(2)/Vs. Devices with pentacene showed a mobility of 0.16 cm(2)/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of similar to...
Citation Formats
A. Ozkan, Y. Keleştemur, H. V. Demir, and E. Y. Erdem, “SILICA SYNTHESIS & COATING OF QUANTUM DOTS IN DROPLET BASED MICROREACTORS,” presented at the 13TH ASME International Conference on Nanochannels, Microchannels, and Minichannels, San-Francisco, Kostarika, 2015, Accessed: 00, 2021. [Online]. Available: