Researcher:
Erten, Ahmet Can

Loading...
Profile Picture
ORCID

Job Title

Teaching Faculty

First Name

Ahmet Can

Last Name

Erten

Name

Name Variants

Erten, Ahmet Can

Email Address

Birth Date

Search Results

Now showing 1 - 8 of 8
  • Placeholder
    Publication
    Solid state sensor for simultaneous measurement of total alkalinity and ph of seawater
    (Amer Chemical Soc, 2017) Briggs, Ellen M.; Sandoval, Sergio; Takeshita, Yuichiro; Kummel, Andrew C.; Martz, Todd R.; Department of Physics; Erten, Ahmet Can; Teaching Faculty; Department of Physics; College of Sciences; 233923
    A novel design is demonstrated for a solid state, reagent-less sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (A(T)) using ion sensitive field effect transistor (ISFET) technology to provide a simplified means of characterization of the aqueous carbon dioxide system through measurement of two "master variables": pH and A(T). ISFET-based pH sensors that achieve 0.001 precision are widely used in various oceanographic applications. A modified ISFET is demonstrated to perform a nanoliter-scale acid base titration of A(T) in under 40 s. This method of measuring A(T), a Coulometric Diffusion Titration, involves electrolytic generation of titrant, through the electrolysis of water on the surface of the chip via a microfabricated electrode eliminating the requirement of external reagents. Characterization has been performed in seawater as well as titrating individual components (i.e., OH-, HCO3-, B(OH)(4)(-), PO43-) of seawater A(T). The seawater measurements are consistent with the design in reaching the benchmark goal of 0.5% precision in A(T) over the range of seawater A(T) of similar to 2200-2500 mu mol kg(-1) which demonstrates great potential for autonomous sensing.
  • Placeholder
    Publication
    Yağ mikrodamlacıklarının gliserol-su çözeltisinde hidrodinamik tuzaklanması
    (IEEE, 2014) Tanyeri, M.; N/A; Department of Physics; Department of Physics; Kayıllıoğlu, Oğuz; Erten, Ahmet Can; Kiraz, Alper; PhD Student; Teaching Faculty; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 233923; 22542
    We demonstrate a novel method for trapping and manipulating microdroplets in liquid media using a hydrodynamic trap. This method enables confinement and long-term observation of biological objects such as cells and macromolecules. / Mikrodamlacıkların sıvı içerisinde tuzaklanmasına ve hareket ettirilmesine olanak sağlayan yeni bir tuzaklama yöntemi sunuyoruz. Geliştirdiğimiz metot hücre ve biyolojik makromoleküllerin sıvı içerisinde tuzaklanması ve uzun süre gözlemlenmesini mümkün kılmaktadır.
  • Placeholder
    Publication
    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.
  • Placeholder
    Publication
    Dye lasing and laminar flow-induced dissolution in hydrodynamically trapped oil microdroplets
    (OSA - The Optical Society, 2015) Tanyeri, M.; Department of Physics; Department of Physics; N/A; Kiraz, Alper; Erten, Ahmet Can; Kayıllıoğlu, Oğuz; Faculty Member; Teaching Faculty; PhD Student; Department of Physics; College of Sciences; College of Sciences; Graduate School of Sciences and Engineering; 22542; 233923; N/A
    Dye lasing and laminar flow-induced dissolution are demonstrated with hydrodynamically trapped oil microdroplets in a glycerol-water solution.
  • Placeholder
    Publication
    Guiding of emulsion droplets in microfluidic chips along shallow tracks defined by laser ablation
    (Springer Heidelberg, 2017) Coskun, Umut Can; Morova, Yagiz; Bozkurt, Asuman Asikoglu; Jonas, Alexandr; Akturk, Selcuk; N/A; Department of Physics; Department of Physics; Rashid, Muhammed Zeeshan; Erten, Ahmet Can; Kiraz, Alper; PhD Student; Teaching Faculty; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 233923; 22542
    We demonstrate controlled guiding of nanoliter emulsion droplets of polar liquids suspended in oil along shallow hydrophilic tracks fabricated at the base of microchannels located within microfluidic chips. The tracks for droplet guiding are generated by exposing the glass surface of polydimethylsiloxane (PDMS)-coated microscope slides via femtosecond laser ablation. The difference in wettability of glass and PDMS surfaces together with the shallow steplike transverse topographical profile of the ablated tracks allows polar droplets wetting preferentially the glass surface to follow the track. In this study, we investigate guiding of droplets of two different polar liquids (water/ethylene glycol) with and without surfactant suspended in an oil medium along surface tracks of different depths of 1, 1.5, and 2 mu m. The results of experiments are also verified with computational fluid dynamics simulations. Guiding of droplets along the tracks as a function of the droplet composition and size and the surface profile depth is evaluated by analyzing the trajectories of moving droplets with respect to the track central axis, and conditions for stable guiding are identified. The experiments and numerical simulations indicate that while the track topography plays a role in droplet guiding using 1.5-and 2-mu m deep tracks, for the case of the smallest track depth of 1 ae m, droplet guiding is mainly caused by surface energy modification along the track rather than the presence of a topographical step on the surface. Our results can be exploited to sort passively different microdroplets mixed in the same microfluidic chip, based on their inherent wetting properties, and they can also pave the way for guiding of droplets along reconfigurable tracks defined by surface energy modifications obtained using other external control mechanisms such as electric field or light.
  • Placeholder
    Publication
    Hydrodynamic trapping of oil microdroplets in glycerol-water solution
    (IEEE, 2003) Tanyeri M.; Department of Physics; Department of Physics; N/A; Kiraz, Alper; Erten, Ahmet Can; Kayıllıoğlu, Oğuz; Faculty Member; Teaching Faculty; PhD Student; Department of Physics; College of Sciences; College of Sciences; Graduate School of Sciences and Engineering; 22542; 233923; N/A
    We demonstrate a novel method for trapping and manipulating microdroplets in liquid media using a hydrodynamic trap. This method enables confinement and long-term observation of biological objects such as cells and macromolecules.
  • Placeholder
    Publication
    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
  • Placeholder
    Publication
    Dependence of erythrocyte deformability on mechanical stress and oxygenation
    (Federation amer Soc Exp Biol, 2017) N/A; N/A; N/A; Department of Physics; N/A; Yalçın, Özlem; Uğurel, Elif; Sağlam, Gökay; Erten, Ahmet Can; Aksu, Ali Cenk; Faculty Member; Researcher; Undergraduate Student; Teaching Faculty; PhD Student; Department of Physics; School of Medicine; School of Medicine; School of Medicine; College of Engineering; Graduate School of Health Sciences; 218440; N/A; N/A; N/A; N/A
    Mechanical properties of erythrocytes are known to be affected by their oxygenation status. Several studies suggested that cytoskeletal rearrangements are carried out in an oxygen dependent manner. The structure of the cytoskeleton determines the mechanical properties of erythrocyte membrane. However, oxygen-dependent mechanical characteristics of erythrocyte are poorly studied whether oxygenated state could alter erythrocyte deformability. In this study, we investigated shear stress induced improvements in erythrocyte deformability through their oxygenation status. Venous blood was collected from male, healthy volunteers (n=10) between 25–50 ages. An informed written consent was obtained from each subject participated in the study according to Declaration of Helsinki. The hematocrit of blood samples adjusted to 0.4 l/l with autologous plasma. Whole blood samples were diluted with polyvinylpyrrolidone (PVP) solution (Mechatronics, Hoorn, Netherlands) with a dilution ratio of 1/200. Blood samples were equilibrated with either ambient air or nitrogen gas for at least 10 minutes at room temperature. Erythrocyte deformability was measured by a laser-assisted optical rotational cell analyzer (LORRCA MaxSis, Mechatronics, Netherlands) applying shear stresses (SS) ranging between 0.3 to 50 Pa. Then, a constant SS of 5, 10 and 20 Pa were applied continuously for 300 seconds and erythrocyte deformability was measured immediately afterwards. Maximal erythrocyte elongation index (EImax) and the SS required for one-half of this maximal deformation (SS1/2) were calculated by using the linear Lineweaver-Burke (LB) model. Deoxygenation of blood samples significantly decreased SS1/2 values both before and after SS applications (p < 0.001). EImax was significantly increased in deoxygenated blood before applying 5 Pa SS (p < 0.05). However, there were no significant differences after continuous SS in oxygenated and deoxygenated blood. Deoxygenation significantly decreased SS1/2/EImax values both before and after SS applications (p < 0.01). SS1/2/EImax values in both oxygenated and deoxygenated blood were significantly decreased after 5 and 10 Pa continuous SS applications although they were not significantly decreased after applying 20 Pa SS. Our study showed for the first time that erythrocyte deformability is improved in deoxygenated conditions in contrast to results presented in previous studies. This deformability improvement may control blood flow and consequently erythrocyte distribution within hypoxic tissues. Our study also demonstrated the relationship of oxygenation-deoxygenation shifts and magnitude of shear stress on erythrocyte deformability.