Browsing by Author "Aktas O."

Now showing 1 - 3 of 3

Open Access
Continuously tunable terahertz metamaterial employing magnetically actuated cantilevers
(Optical Society of American (OSA), 2011) Ozbey, B.; Aktas O.
Terahertz metamaterial structures that employ flexing microelectromechanical cantilevers for tuning the resonance frequency of an electric split-ring resonator are presented. The tuning cantilevers are coated with a magnetic thin-film and are actuated by an external magnetic field. The use of cantilevers enables continuous tuning of the resonance frequency over a large frequency range. The use of an externally applied magnetic field for actuation simplifies the metamaterial structure and its use for sensor or filter applications. A structure for minimizing the actuating field is derived. The dependence of the tunable bandwidth on frequency is discussed. © 2011 Optical Society of America.
Open Access
Label-Free Biosensing with High Selectivity in Complex Media using Microtoroidal Optical Resonators
(Nature Publishing Group, 2015) Ozgur, E.; Toren P.; Aktas O.; Huseyinoglu, E.; Bayındır, Mehmet
Although label-free biosensors comprised of optical microcavities inherently possess the capability of resolving molecular interactions at individual level, this extreme sensitivity restricts their convenience for large scale applications by inducing vulnerability towards non-specific interactions that readily occur within complex media. Therefore, the use of optical microresonators for biosensing is mostly limited within strictly defined laboratory conditions, instead of field applications as early detection of cancer markers in blood, or identification of contamination in food. Here, we propose a novel surface modification strategy suitable for but not limited to optical microresonator based biosensors, enabling highly selective biosensing with considerable sensitivity as well. Using a robust, silane-based surface coating which is simultaneously protein resistant and bioconjugable, we demonstrate that it becomes possible to perform biosensing within complex media, without compromising the sensitivity or reliability of the measurement. Functionalized microtoroids are successfully shown to resist nonspecific interactions, while simultaneously being used as sensitive biological sensors. This strategy could pave the way for important applications in terms of extending the use of state-of-the-art biosensors for solving problems similar to the aforementioned.
Open Access
Low leakage current operation of carbon nanotube network thin-film transistors at 100 degree celsius
(2011) Ozturk, S.; Aktas O.
In this work we present the elevated temperature operation of carbon nanotube thin film transistors up to 100 °C in air ambient. It is demonstrated that for semiconducting nanotubes the OFF current leakage does not increase and the high ON/OFF ratio of transistors consisting of semiconducting nanotubes is preserved up to 100 °C. In addition, we investigate the factors affecting the operation of carbon nanotube transistors at high temperature for a range of source-to-drain spacing and metallic tube contents. The influence of change in tube-tube and tube-metal contact resistance on the device characteristics at high temperature is demonstrated. © 2011 American Scientific Publishers.