Researcher:
Eryürek, Mustafa

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Mustafa

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Eryürek

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Eryürek, Mustafa

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2015 - 201711

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    Optical sensor for humidity and hydrogen gas based on polymer microresonators
    (IEEE, 2016) Karadağ, Y.; Kılınç, N.; Department of Physics; N/A; N/A; Department of Physics; Department of Mechanical Engineering; Kiraz, Alper; Eryürek, Mustafa; Taşdemir, Zuhal; Anand, Suman; Alaca, Burhanettin Erdem; Faculty Member; PhD Student; PhD Student; Researcher; Faculty Member; Department of Physics; Department of Mechanical Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Science; College of Engineering; 22542; N/A; N/A; N/A; 115108
    Summary form only given. We report humidity and hydrogen sensors employing elastic polymer (SU-8) optical microresonators fabricated with photolithography. The sensing mechanism relies on monitoring the spectral shifts of the optical whispering gallery modes (WGMs) in the transmission spectra recorded from the microresonators. WGMs are excited through SU-8 waveguides in which a tunable laser light is coupled from an optical fiber.
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    Efficient optical fiber coupling to whispering gallery modes of optically manipulated emulsion microdroplets
    (Electromagnetics Academy, 2015) Karadag, Y.; Department of Physics; N/A; Department of Physics; Department of Physics; Anand, Suman; Eryürek, Mustafa; Serpengüzel, Ali; Kiraz, Alper; Researcher; PhD Student; Faculty Member; Faculty Member; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; 27855; 22542
    We demonstrate efficient coupling to the optical whispering gallery modes of a spherical resonator consisting of a liquid droplet embedded in another liquid medium. Whispering gallery mode particle sensing experiment is commonly performed with solid resonators, whereby the sensing volume is limited to the weak evanescent tail of the mode near the resonator surface. In this work, we demonstrate efficient coupling to the optical whispering gallery modes by introducing a portable, all liquid emulsion microdroplet resonator held in a single beam optical trap. We have observed coupling to the fundamental whispering gallery modes of 10 to 60 nm diameter emulsion droplets at 1550 nm. The experimental challenges towards making, stabilizing and coupling to the droplet resonators are also addressed in this paper.
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    Single-slot hybrid microring resonator hydrogen sensor
    (Optical Soc Amer, 2017) Çiçek, Kenan; N/A; Department of Physics; Eryürek, Mustafa; Kiraz, Alper; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542
    Photonic integrated circuits fabricated on silicon-on-insulator platforms offer convenient foundations to implement highly sensitive, compact, robust, and low-cost technology in sensing applications. The potential of this technology in hydrogen gas sensing is discussed in this study. A single-slot hybrid microring-resonator-(MRR) based hydrogen gas sensor utilizing a coaxial palladium (Pd) microdisk is demonstrated. Detection is based on expansion of Pd upon hydrogen exposure toward the slot between the outer radius of the Pd microdisk and the inner radius of the MRR and the subsequent shift of the whispering gallery modes (WGMs) propagating in the MRR. Finite-difference time-domain simulations indicate a sensitivity as high as 11.038 nm/% hydrogen, provided that optimum geometrical design parameters are chosen. This sensitivity value is similar to 23 times higher than other existing WGM-based hydrogen sensor demonstrations. (C) 2017 Optical Society of America
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    Enhanced dissolution of liquid microdroplets in the extensional creeping flow of a hydrodynamic trap
    (Amer Chemical Soc, 2016) Tanyeri, Melikhan; N/A; Department of Physics; N/A; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Department of Physics; Mustafa, Adil; Erten, Ahmet Can; Ayaz, Rana Muhammed Armaghan; Kayıllıoğlu, Oğuz; Eser, Ayşenur; Eryürek, Mustafa; Irfan, Muhammad; Muradoğlu, Metin; Kiraz, Alper; PhD Student; Teaching Faculty; PhD Student; PhD Student; Master Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Mechanical Engineering; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Sciences; N/A; 233923; N/A; N/A; N/A; N/A; N/A; 46561; 22542
    A novel noncontact technique based on hydrodynamic trapping is presented to study the dissolution of freely suspended liquid microdroplets into a second immiscible phase in a simple extensional creeping flow. Benzyl benzoate (BB) and n-decanol microdroplets are individually trapped at the stagnation point of a planar extensional flow, and dissolution of single microdroplets into an aqueous solution containing surfactant is characterized at different flow rates. The experimental dissolution curves are compared to two models: (i) the Epstein-Plesset (EP) model which considers only diffusive mass transfer, and (ii) the Zhang-Yang-Mao (ZYM) model which considers both diffusive and convective mass transfer in the presence of extensional creeping flow. The EP model significantly underpredicts the experimentally determined dissolution rates for all experiments. In contrast, very good agreement is observed between the experimental dissolution curves and the ZYM model when the saturation concentration of the microdroplet liquid (c(s)) is used as the only fitting parameter. Experiments with BB microdroplets at low surfactant concentration (10 mu M) reveal c(s) values very similar to that reported in the literature. In contrast, experiments with BB and n-decanol microdroplets at 10 mM surfactant concentration, higher than the critical micelle concentration (CMC) of 5 mM, show further enhancements in microdroplet dissolution rates due to micellar solubilization. The presented method accurately tests the dissolution of single microdroplets into a second immiscible phase in extensional creeping flow and has potential for applications such as separation processes, food dispersion, and drug development/design.
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    Integrated humidity sensor based on SU-8 polymer microdisk microresonator
    (Elsevier Science Sa, 2017) Y. Karadag; N. Kilinc; N/A; N/A; Department of Physics; Department of Mechanical Engineering; Department of Physics; Eryürek, Mustafa; Taşdemir, Zuhal; Anand, Suman; Alaca, Burhanettin Erdem; Kiraz, Alper; PhD Student; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Mechanical Engineering; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; College of Sciences; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; N/A; N/A; 115108; 22542
    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.
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    Optical sensor for hydrogen gas based on a palladium-coated polymer microresonator
    (Elsevier, 2015) Karadag, Yasin; Tasaltin, Nevin; Kilinc, Necmettin; N/A; Department of Physics; Eryürek, Mustafa; Kiraz, Alper; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542
    We report an integrated optical sensor of hydrogen (H-2) gas employing an SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide. The sensing mechanism relies on the expansion in the Pd lattice due to palladium hydride formation in the presence of H-2. Strain induced in the microresonator then causes a red shift of the spectral positions of the resonator whispering gallery modes (WGMs) which is monitored using a tunable laser coupled to the waveguide. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 and 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/% H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers. (C) 2015 Elsevier B.V. All rights reserved.
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    Observation of whispering gallery modes in elastic light scattering from microdroplets optically trapped in a microfluidic channel
    (Optical Soc Amer, 2016) Karadağ, Yasin; Jonas, Alexandr; Department of Physics; N/A; Department of Physics; Department of Physics; Department of Physics; Anand, Suman; Eryürek, Mustafa; Erten, Ahmet Can; Serpengüzel, Ali; Kiraz, Alper; Researcher; PhD Student; Teaching Faculty; Faculty Member; Faculty Member; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; 233923; 27855; 22542
    Optical whispering gallery modes (WGMs) were observed in elastic scattering spectra recorded from oil-in-water emulsion droplets in a microfluidic channel. Droplets with diameters ranging between 15 and 50 mu m were trapped by optical tweezers near the tip of a single mode fiber that enabled the excitation of the WGMs using a tunable laser. Quality factors of the WGMs were observed to increase with droplet size. WGMs with quality factors of more than 10(4) were observed for droplets with diameters around 45 mu m. In some cases, recorded WGMs drifted monotonically to the blue end of the spectrum due to droplet dissolution in the host liquid. Fluctuating spectral shifts to both blue and red ends of the spectrum were also observed. These were attributed to the presence of randomly diffusing particulate contaminants in the droplet liquid, indicating the potential of optically trapped droplet resonators for optical sensing applications. (C) 2016 Optical Society of America
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    Liquid refractometric sensors based on optical fiber resonators
    (Elsevier Science Sa, 2017) Jonas, Alexandr; Çiçek, Kenan; N/A; N/A; N/A; Department of Physics; Eryürek, Mustafa; Ghafoor, Moeen; Bavili, Nima; Kiraz, Alper; PhD Student; Researcher; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; N/A; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 22542
    A robust, easy-to-fabricate, and sensitive liquid refractometric sensor utilizing optical fiber resonators (OFRs) obtained by simple stripping and cleaning of conventional optical fibers is presented. The sensing scheme is based on recording the spectral changes of the whispering gallery modes (WGMs) observed in the transmission spectrum of an OFR excited with a tunable laser coupled to the OFR through an independent tapered optical fiber. The demonstrated sensor device is tested and fully characterized with water solutions of ethanol and ethylene glycol (EG). Good agreements are obtained with theoretical predictions for both ethanol and EG cases when TE and TM polarized WGMs are considered. The limit of detection of the demonstrated sensor is determined to be between 2.7 and 4.7 x 10(-5) refractive index unit (RIU) comparable to the state-of-the-art when precise temperature control of the sample chamber is missing. (C) 2017 Elsevier B.V. All rights reserved.
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    Hydrogen and humidity sensing based on WGMs of elastic polymer optical microresonators
    (Electromagnetics Academy, 2015) N/A; Department of Physics; Department of Physics; Eryürek, Mustafa; Anand, Suman; Kiraz, Alper; PhD Student; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; 22542
    We report hydrogen and humidity sensor employing elastic polymer (SU-8) optical microresonators. The sensing mechanism relies on the optical whispering gallery mode (WGM) resonance shifts in the transmission spectra of these microresonators. WGMs are excited through SU-8 waveguides in which a tunable laser light is coupled from an optical fiber. Relative humidity between 0 and 65% is detected at room temperature. For hydrogen sensing, the microresonators are coated with a thin layer of palladium (Pd) metal layer to increase the sensing performance. Hydrogen gas is detected reversibly between 0.3 and 1.5%. Hydrogen gas concentrations higher than 1.5% result irreversible degradation of the devices because of a phase transition occurring in the Pd layer.
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    PublicationOpen Access
    Hydrogen gas sensing using palladium-coated microdisk microresonators
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2015) Taşaltın, Nevin; Department of Physics; Eryürek, Mustafa; Karadağ, Yasin; Kılınç, Necmettin; Kiraz, Alper; PhD Student; PhD Student; Faculty Member; Department of Physics; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 22542
    An SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide is used to as a hydrogen (H-2) gas sensor. In the presence of H2 a red shift is observed in the spectral positions of the microdisk whispering gallery modes (WGMs) due to the expansion in the Pd lattice. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/%H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers.