Papers by Ata Tuna CIFTLIK
Journal of Micromechanics and Microengineering, 2011
We introduce a new low-temperature (280 °C) parylene-to-SiO2 bonding process with high device yie... more We introduce a new low-temperature (280 °C) parylene-to-SiO2 bonding process with high device yield (>90%) for the fabrication and integration of high-pressure-rated microfluidic chips. Pull tests demonstrate a parylene-to-SiO2 bonding strength of 10 ± 3 MPa. We apply this technique for bonding Pyrex and silicon wafers having multiple metal layers to fabricate standard packaged microfluidic devices. By performing electrochemical impedance spectroscopy of electrolyte solutions in such devices, we demonstrate that electrodes remain functional after the etching, bonding and dicing steps. We also develop a high-pressure microfluidic and electrical integration technology, eliminating special fluidic interconnections and wire-bonding steps. The burst pressure of the integrated system is statistically shown to be 7.6 ± 1.3 MPa, with a maximum achieved burst pressure of 11.1 MPa, opening perspectives for high-pressure applications of these types of microfluidic devices.
We introduce a new low temperature (280°C) parylene-C wafer bonding technique, where parylene-C b... more We introduce a new low temperature (280°C) parylene-C wafer bonding technique, where parylene-C bonds directly a Pyrex wafer to a silicon wafer with either a Si, SiO2 or Si3N4 surface with a bonding strength up to 23 MPa. The technique uses a single layer of parylene-C deposited only on the Pyrex wafer. Moreover, the process is compatible for bonding any type of wafer with small-sized micropatterned features, or containing microfluidic channels and electrodes. This technique can be an alternative for conventional bonding methods like anodic bonding in applications requiring a low temperature and diverse bonding interfaces.
Microfluidics and Nanofluidics, 2011
We present an active fixed-volume mixer based on the creation of multiple source–sink microfluidi... more We present an active fixed-volume mixer based on the creation of multiple source–sink microfluidic flows in a polydimethylsiloxane (PDMS) chip without the need of external or internal pumps. To do so, four different pressure-controlled actuation chambers are arranged on top of the 5 μl volume of the mixing chamber. After the mixing volume is sealed/fixed by microfluidic valves made using ‘microplumbing technology’, a virtual source–sink pair is created by pressurizing one of the membranes and, at the same time, releasing the pressure of a neighboring one. The pressurized air deforms the thin membrane between the mixing and control chambers and creates microfluidic flows from the squeezed region (source) to the released region (sink) where the PDMS membrane is turned into the initial state. Several schemes of operation of virtual source–sink pairs are studied. In the optimized protocol, mixing is realized in just a sub-second time interval, thanks to the implementation of chaotic advection.
This paper represents a direct injection method for leukocytes into microfluidic channels using n... more This paper represents a direct injection method for leukocytes into microfluidic channels using negative dielectrophoresis. The blood sample is a heparinated pure blood droplet and injection is realized on-chip without any external microfluidic connections to the microchip. During injection erythrocytes are immobilized in-situ at injection reservoir electrodes. The method is easily applicable to most BioMEMS applications requiring direct injection of cells from pure blood and to eliminate pressure driven control.
This paper presents the design and implementation of a resonator-type high-resolution gravimetric... more This paper presents the design and implementation of a resonator-type high-resolution gravimetric sensor, which allows detection in liquid media without severe degradation of the quality factor and the resolution. The proposed system eliminates the drawbacks of traditional cantilever- based detectors by lateral motion of the mechanical structure, which significantly decreases squeeze-film damping. It has been experimentally verified that the system
This paper presents the design and implementation of a novel dielectrophoresis (DEP) system with ... more This paper presents the design and implementation of a novel dielectrophoresis (DEP) system with spiral channels and concentric electrodes for high resolution cell separation applications. The device is fabricated with a 4 mask parylene process and the design is optimized in MATLAB Simulinkreg to confine the operation. Tests with micro particles of different sizes are performed to show size-based separation by dielectrophoresis. Proposed device is also tested with K562 leukemia cell lines to prove that they can be separated from healthy leukocytes due to the difference in their electrical properties.
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Papers by Ata Tuna CIFTLIK