Browsing by Subject "Composite micromechanics"

Now showing 1 - 5 of 5

Open Access
Metamaterial-based wireless RF-MEMS strain sensors
(IEEE, 2010) Melik, Rohat; Ünal, Emre; Perkgoz, Nihan Kosku; Puttlitz, C.; Demir, Hilmi Volkan
Approximately 10% of the fractures do not heal properly because of the inability to monitor fracture healing. Standard radiography is not capable of discriminating whether bone healing is occurring normally or aberrantly. We propose and develop an implantable wireless sensor that monitors strain on implanted hardware in real time telemetrically. This enables clinicians to monitor fracture healing. Here we present the development and demonstration of metamaterial-based radiofrequency (RF) micro-electro-mechanical system (MEMS) strain sensors for wireless strain sensing to monitor fracture healing. The operating frequency of these sensors shifts under mechanical loading; this shift is related to the surface strain of the implantable test material. In this work, we implemented metamaterials in two different architectures as bio-implantable wireless strain sensors for the first time. These custom-design metamaterials exhibit better performance as sensors than traditional RF structures (e.g., spiral coils) because of their unique structural properties (splits). They feature a low enough operating frequency to avoid the background absorption of soft tissue and yield higher Q-factors compared to the spiral structures (because their gaps have much higher electric field density). In our first metamaterial architecture of an 5x5 array, the wireless sensor shows high sensitivity (109kHz/kgf, 5.148kHz/microstrain) with low nonlinearity-error (<200microstrain). Using our second architecture, we then improved the structure of classical metamaterial and obtained nested metamaterials that incorporate multiple metamaterials in a compact nested structure and measured strain telemetrically at low operating frequencies. This novel nested metamaterial structure outperformed classical metamaterial structure as wireless strain sensors. By employing nested metamaterial architecture, the operating frequency is reduced from 529.8 MHz to 506.2 MHz while the sensitivity is increased from 0.72 kHz/kgf to 1.09 kHz/kgf. ©2010 IEEE.
Open Access
Micromachining with square-Shaped 1 ns-Long pulses from an all-Fiber Yb-Doped laser-Amplifier system
(Optical Society of America, 2011) Özgören, Kıvanç; Öktem, Bülent; İlday, F. Ömer; Pasin, Ece; Eken, K.
We demonstrate micromachining with 1ns-long pulses from an all-fiber laser. Fiber lasers generating uncompressible long pulses have been ignored as undesired operational modes, however their robust, low-repetition-rate operation is well suited to micromachining. © 2011 Optical Society of America.
Open Access
Modeling and cross coupling controller development for a 6DOF laser micro-machining system
(IEEE, 2017) Kerimoğlu, Serhat; Çakmakçı, Melih
In recent years, studies on manufacturing systems have proved the importance of cooperation of positioning systems with laser cutting technology. The performance of the manufacturing system can be improved by utilizing both laser and positioning systems together. In this study, modeling and cross coupling controller development of a micromachining system which can perform on non-linear contoured surfaces is presented. Laser micromachining system is designed and assembled including a nanosecond Q-switched pulsed fiber laser, a 6-DOF hexapod manipulator, a granite table in order to absorb vibrations and an external cabin system to isolate the whole system for safety and health issues. The positioning system used here has fast response and precise positioning capabilities with a wide range of workspace. However, its performance of machining non-linear surfaces can be further improved by using a cross coupled control algorithm. On top of the loop based controllers an add-on controller is developed to improve the contouring performance by including the effects of the other feedback loops on the overall controller. Actual laser cutting results also show improvements due to the improvements in the positioning system performance.
Open Access
Nanoelectromechanical switches for reconfigurable antennas
(2010) Cetiner, B.A.; Bıyıklı, Necmi; Yildirim, B.S.; Damgaci, Y.
We report on the full-wave analyses of a frequency reconfigurable antenna integrated with metallic nanoelectromechanical system (NEMS) switches (length = 3 μm, width = 60 nm). The NEMS switch used in this work has the same architecture with low voltage, double-arm cantilever-type metallic DC-contact microelectromechanical system (MEMS) switch recently developed in author's group. The microfabrication and characterization of the MEMS switch have also been given in this article. Copyright © 2009 Wiley Periodicals, Inc.
Open Access
Ultrafast micromachining of Cu and Si at ultra-high repetition rates with pulse bursts
(IEEE, 2016) Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Yavuz, Koray; Mirza I.; Bulgakova N.M.; İlday, F. Ömer
We report a novel ultrafast burst mode fiber laser system, which can deliver pulses at ultra-high repetition rates in order to systematically investigate micromachining efficiency on copper and silicon samples. © 2015 IEEE.