Makine Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/263
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Conference Object Citation - WoS: 12Citation - Scopus: 13A Reconfigurable Microfluidic Transmitarray Unit Cell(Ieee, 2013) Erdil, Emre; Yıldırım, Ender; Topalli, Kagan; Zorlu, Ozge; Toral, Taylan; Yildirim, Ender; Kulah, Haluk; Civi, Ozlem Aydin; Makine MühendisliğiThis paper presents a novel microfluidics based approach to develop a reconfigurable circularly polarized transmitarray unit cell. The unit cell comprises double layer nested split ring slots formed as microfluidic channels that can be filled by fluids. Split regions in the slots are realized by injecting liquid metal into the channels. Beam steering is obtained by implementing rotational phase shifting via manipulating the liquid metal in the slots. X-band unit cell prototypes are fabricated on glass substrate carrying a patterned metal film, and the slot channels are formed by Polydimethylsiloxane (PDMS) using soft lithography techniques.Article Citation - WoS: 30Citation - Scopus: 33Investigation on Replication of Microfluidic Channels by Hot Embossing(Taylor & Francis inc, 2017) Arikan, M. A. Sahir; Cogun, Ferah; Yildirim, Ender; Sahir Arikan, M.A.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.Article Citation - WoS: 7Citation - Scopus: 9A Novel Zero-Dead Sample Loading Interface for Microfluidic Devices: Flexible Hydraulic Reservoir (Fhr)(Iop Publishing Ltd, 2018) Cetin, Barbaros; Yildirim, Ender; Hatipoglu, UtkuInfusing minute amounts of valuable liquids such as samples to microfluidic chips by using common pumping schemes such as syringe pumps often result in an excessive dead-volume. We present a simple yet effective sample loading interface, which helps by pumping the sample to the chip by using the hydraulic pressure generated by the syringe pump. Results show that sample volumes as low as 25 mu l can be delivered at flow rates ranging between 10-30 mu l min(-1). Maximum dead volume ratio was observed to be 3% when infusing 200 mu l of sample at 10 mu l min(-1).