Browsing by Author "Arikan, M. A. Sahir"

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Citation - WoS: 29
Citation - Scopus: 32
Investigation on Replication of Microfluidic Channels by Hot Embossing
(Taylor & Francis inc, 2017) Arikan, M. A. Sahir; Cogun, Ferah; Yildirim, Ender; 31835; 01. Çankaya Üniversitesi; 06. Mühendislik Fakültesi; 06.06. Makine Mühendisliği
In this study, effects of embossing temperature, time, and force on production of a microfluidic device were investigated. Polymethyl methacrylate (PMMA) substrates were hot embossed by using a micromilled aluminum mold. The process parameters were altered to observe the variation of replication rate in width and depth as well as symmetry of the replicated microfluidic channels. Analysis of variance (ANOVA) on the experimental results indicated that embossing temperature was the most important process parameter, whereas embossing time and force have less impact. One distinguishing aspect of this study is that, the channels were observed to be skewed to either side of the channel depending on the location of the protrusions on the mold. The mechanism of the skewness was investigated by finite element analysis and discussed in detail. Results showed that the skewness depends on the flow characteristics of the material and could be reduced by increasing the embossing temperature. The best replication rates were obtained at parameter settings of 115 degrees C, 10kN, and 8min for the molds with minimum 56 mu m wide features of 120 mu m depth. We also showed that the fabricated channels could be successfully sealed by solvent-assisted thermo-compressive bonding at 85 degrees C under 5.5kN force.
Citation - WoS: 43
Citation - Scopus: 54
A Normally Closed Electrostatic Parylene Microvalve for Micro Total Analysis Systems
(Elsevier Science Sa, 2012) Arikan, M. A. Sahir; Kulah, Haluk; Yildirim, Ender; 120121; 01. Çankaya Üniversitesi; 06. Mühendislik Fakültesi; 06.06. Makine Mühendisliği
This paper presents an electrostatically actuated, normally closed microvalve for parylene microfluidics. The proposed valve structure isolates the fluid from the electric field, and hence results in relatively low actuation potentials (<60 V) irrespective of the working fluid. Hereby, the microvalve solves electrolysis or electrode shielding problems observed in electrostatic actuation in micro total analysis systems. To investigate leakage properties, microvalves were tested under pressurized flow with de-ionized (DI) water. No detectable leakage ratio was observed up to 20 kPa inlet pressure, due to the unique semicircular valve seat design. It was shown that the valve seat could be reconfigured to enable sealing at various pressure levels for different applications. (C) 2012 Elsevier B.V. All rights reserved.