Browsing by Author "Kulah, Haluk"

Now showing 1 - 3 of 3

Citation - WoS: 43
Citation - Scopus: 54
A normally closed electrostatic parylene microvalve for micro total analysis systems
(Elsevier Science Sa, 2012) Yildirim, Ender; Yıldırım, Ender; Arikan, M. A. Sahir; Kulah, Haluk; 120121; 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.
Citation - WoS: 12
Citation - Scopus: 13
A Reconfigurable Microfluidic Transmitarray Unit Cell
(Ieee, 2013) Erdil, Emre; Yıldırım, Ender; Topalli, Kagan; Zorlu, Ozge; Toral, Taylan; Yildirim, Ender; Kulah, Haluk; Civi, Ozlem Aydin; 31835); Makine Mühendisliği
This 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.
Citation - WoS: 15
Citation - Scopus: 17
Electrostatic energy harvesting by droplet-based multi-phase microfluidics
(Springer Heidelberg, 2012) Yildirim, Ender; Yıldırım, Ender; Kulah, Haluk; 120121; Makine Mühendisliği
This paper presents an energy scavenging technique, merging microfluidics with electrostatic energy harvesting. The method employs droplet-based microflow of two phases with different electrical permittivities, resulting in a capacitance change across the microchannel, to harvest electrical energy. The technique is implemented on 3 mm wide, 1 mm deep minichannels. It is shown that 0.4 nW can be harvested using a single electrode pair, with air and water as the two phases flowing at 1 ml/min. The generated power can be increased significantly by microscale implementation, where the number of electrodes can also be increased for further improvement.