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Öğe H-2 sensing properties of Cu2O nanowires on glass substrate(ELSEVIER SCIENCE BV, 2015) Sisman, O.; Kilinc, N.; Ozturk, Z. Z.; Urban, G; Wollenstein, J; Kieninger, JThe synthesis of Cu2O of nanowires on glass substrate was investigated for usage as a H-2 sensor device. The amorphous copper oxide nanowires were synthesized on glass substrate via thin film anodization in 0,2M KOH + 0,1M NH4F solution. The nanowires were crystallized with annealing the samples at 280 C under vacuum conditions. The structural changes of nanowires were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The DC electrical measurements of Cu2O nanowires were carried out in the temperature range of 303-473 K under 200 sccm dry air flow. The H-2 sensing properties of as-synthesized sample after anodization and vacuum annealed sample were compared at 200 degrees C under dry air flow. The Cu2O nanowires showed better sensor response than as -synthesized sample. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ric-nd/4.0/) Peer-review under responsibility of the organizing committee of EUROSENSORSÖğe Integrated humidity sensor based on SU-8 polymer microdisk microresonator(ELSEVIER SCIENCE SA, 2017) Eryurek, M.; Tasdemir, Z.; Karadag, Y.; Anand, S.; Kilinc, N.; Alaca, B. E.; Kiraz, A.Due to its high interaction with water vapor and photolithographic patterning property, SU-8 is a favorable hygroscopic polymer for developing humidity sensors. In addition, optical resonances of optical microresonators are very sensitive to the dianges in their environment. Here, we present integrated optical humidity sensors based on chips containing SU-8 polymer microdisks and waveguides fabricated by single-step UV photolithography. The performance of these sensors is tested under a wide range of relative humidity (RH) levels (0-50%). A tunable laser light is coupled from an excitation fiber to individual SU-8 waveguides using end-face coupling method. As the laser wavelength is scanned, the whispering gallery modes (WGMs) are revealed as dips in the transmission spectra. Sensing is achieved by recording spectral shifts of the WGMs of the microdisk microresonators. Red shift is observed in the WGMs with increasing RH. Between 0 and 1% RH, an average spectral shift sensitivity of 108 pm/% RH is demonstrated from measurements performed on 4 sensor devices. This sensitivity is comparable to the highest values obtained using microresonators in the literature. Measurements performed with another sensor device revealed a decrease in sensitivity by only around 3 times when RH is increased to 45-50%. Finite element modeling simulations are carried out to determine the dominant effect responsible for the resonance shift. The results show that the refractive index change is more important than the microresonator size change. The standard deviation in wavelength measurement is <3 pm, indicating a limit of detection better than 0.03% RH. These results suggest that optical sensor devices that contain integrated SU-8 microresonators and waveguides can be employed as easy-to-fabricate and sensitive humidity sensors. (C) 2016 Elsevier B.V. All rights reserved.Öğe Optical Sensor for Humidity and Hydrogen Gas Based on Polymer Microresonators(IEEE, 2016) Kiraz, A.; Eryurek, M.; Tasdemir, Z.; Karadag, Y.; Anand, S.; Kilinc, N.; Alaca, B. E.[Abstract Not Available]Öğe Precision density and viscosity measurement using two cantilevers with different widths(ELSEVIER SCIENCE SA, 2015) Cakmak, O.; Ermek, E.; Kilinc, N.; Yaralioglu, G. G.; Urey, H.We introduce a novel method for fast measurement of liquid viscosity and density using two cantilevers with different geometries. Our method can be used for real-time monitoring in lab on chip systems and offer high accuracy for a large range of densities and viscosities. The measurement principle is based on tracking the oscillation frequencies of two cantilevers with a phase-locked loop (PLL) and comparing with reference measurements with a known fluid. A set of equations and a simple algorithm is developed to relate the density and the viscosity to the frequency shifts of the cantilevers. We found that the effect of the density and the viscosity can be well separated if cantilevers have different widths. In the experiments, two Nickel microcantilevers (widths 25 pm and 100 mu m, length: 200 mu m, thickness: 1.75 mu m) were fully immersed in the liquid and the temperature was controlled. The actuation was using an external electrocoil and the oscillations were monitored using laser Doppler vibrometer. Thus, electrical connections to the cantilevers are not required, enabling measurements also in conductive liquids. The PLL is used to set the phase difference to 900 between the actuator and the sensor. Calibration measurements were performed using glycerol and ethylene glycol solutions with known densities and viscosities. The measurement error with the new method was lower than 3% in density in the range 995-1150 kg/m(3) and 4.6% in viscosity in the range 0.935-4 mPa.s. Based on the signal-to-noise ratio, the minimum detectable difference in the viscosity is 1 mu Pa.s and the density is 0.18 kg/m(3). Further improvements in the range and the accuracy are possible using 3 or more cantilevers with different geometries. (C) 2015 Elsevier B.V. All rights reserved.
