Browsing by Author "Demiralp, Berke"

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Bocce sporunun Türkiye’ye gelişi ve gelişimi
(Bilkent University, 2017) Çoşkuner, Ege; Demiralp, Berke; Sarı, Burak; Topuz, Alper; Özcan, Faruk Yücel; Uygunca, Vesile Beste
Open Access
Monitoring micromechanical buckling at high-speed for sensing and transducer applications
(IEEE, 2021-08-06) Demiralp, Berke; Pisheh, Hadi Sedaghat; Küçükoğlu, Berk; Hatipoğlu, Utku; Hanay, Mehmet Selim
Controlling the amount and direction of buckling at micro- and nano-scale efficiently opens up avenues for novel actuation and sensor applications. Earlier platforms that can achieve a full and non-thermal control of microscopic buckling operated only with a time resolution of 40 ms. Here, we have measured the buckling amount of a beam starting from unbuckled position and reaching to large post-buckling deformations by collecting secondary electrons under scanning electron microscope. Line mode is used for ultrafast measurements with 33kHz scan frequency, and a displacement noise floor of 40pm/√Hz was obtained. Moreover, by further reduction in the device dimensions, the buckling threshold voltage was reduced by a factor of three compared to similar platforms.
Open Access
Nanomechanical buckling for applications in nonlinear dynamics
(2021-07) Demiralp, Berke
There has not been enough attention on post buckling behavior at nano scale even though it reveals rich nonlinear and chaotic dynamics and has potential to be used on cutting edge sensing, actuation, computation and communication applications. Here, full motion of the nanomechanical buckling, starting from un-buckled position to large deformations at post buckling regime has been precisely measured with error bars of ±7 nm for large deformation regime and ±2.8 nm for √ initial bending, with a noise ﬂoor of 38.5 pm/ Hz. Line mode of SEM is used for deﬂection detection which uses secondary electrons collected from sample and relevant code is developed for data processing. Initial bending, initial buckling and inﬂection point are well deﬁned which can help us to understand transition to post buckling regime and development of sensors and actuators. Additionally, one well oscillation, double well oscillation and chaotic trajectories are investi-gated using the system as forced double well oscillator. Trajectory plotting is performed with an image processing code which beneﬁts from contrast diﬀerence of the device and environment. A new region within double well oscillation regime is observed where motion converts from one well oscillation to double well oscilla-tion which could be a candidate on mechanical computation and communication applications. Also, a preliminary design for synchronized chaos experiments using the same buckling platform is developed. Finally, an optomechanical experimental setup and chip is built for measure-ment of one or multiple NEMS beams. Fiber optic techniques are used for exper-imental setup and grating couplers, ring/racetrack resonators are develoxper-imental setup and grating couplers, ring/racetrack resonators are developed for beam measurements. Critical couplings on multiple devices are observed.
Embargo
Observing inter-well and intra-well oscillations in buckled nanomechanical systems enabled by image processing
(AIP Publishing LLC, 2023-12-08) Erdem, Ege; Demiralp, Berke; Pisheh, Hadi S.; Firoozy, Peyman; Karakurt, Ahmet Hakan; Hanay, Mehmet Selim
The scanning electron microscope (SEM) recordings of dynamic nano-electromechanical systems (NEMS) are difficult to analyze due to the noise caused by low frame rate, insufficient resolution, and blurriness induced by applied electric potentials. Here, we develop an image processing platform enhanced by the physics of the underlying system to track the motion of buckling NEMS structures in the presence of high noise levels. The algorithm is composed of an image filter, two data filters, and a nonlinear regression model, which utilizes the expected form of the physical solution. The method was applied to the recordings of a NEMS beam about 150 nm wide, undergoing intra- and inter-well post-buckling states with a transition rate of approximately 0.5 Hz. The algorithm can track the dynamical motion of the NEMS and capture the dependency of deflection amplitude on the compressive force on the beam. With the help of the proposed algorithm, the transition from inter-well to intra-well motion is clearly resolved for buckling NEMS imaged under SEM.