Browsing by Author "AYDEMİR, UMUT"

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Ann-based estimation of mems diaphragm response: An application for three leaf clover diaphragm based fabry-perot interferometer
(Elsevier Sci Ltd, 2022-06-28) Hayber, Sekip Esat; YİĞİT, ENES; Aydemir, Umut; AYDEMİR, UMUT; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Elektrik ve Elektronik Bölümü.; 0000-0001-5396-4610; AGY-4584-2022; JFJ-3503-2023
In this study, an artificial neural network (ANN) based model is developed for MEMS diaphragm analysis, which does not require difficult and time-consuming FEM processes. ANN-based estimator is generated for static pressure response (d) and dynamic pressure response (f) analysis of TLC (three leaf clover) diaphragms for FabryPerot interferometers as an example. TLC is one of the unsealed MEMS design diaphragms formed by three leaves of equal angles. The diaphragms used to train ANNs are designed with SOLIDWORKS and analyzed with ANSYS. A total of 1680 TLC diaphragms are simulated with eight diaphragm parameters (3 for SiO2 material, 4 for geometry, and 1 for pressure) to create a data pool for ANN's training, validation, and testing processes. 80% of the data is used for training, 15% for validation, and the remaining for testing. Only four geometric parameters are used as input in the ANN estimator, and the material parameters are added to the model with an analytical multiplier. Thus, network models that estimate d and f values for all kinds of diaphragm materials are proposed, with a material-independently trained ANN structure. The performance of the ANN model is compared with the empirical equation suggested in the literature, and its superiority is demonstrated. In addition, the d and f parameters of TLC diaphragms designed with five different materials (Si, In2Se3, Ag, EPDM, Graphene) are estimated to be very close to the real ones. By using the proposed method, analyses of TLC diaphragms are quickly performed without the need for time-consuming and costly design and analysis programs.
Design and simulation of a novel fungus-shaped center embossed diaphragm for fiber optic pressure sensors
(Elsevier Science, 2021-01) Hayber, Şekip Esat; Aydemir, Umut; AYDEMİR, UMUT; 0000-0001-5396-4610; IXW-8105-2023
A novel structure with a fungus-shaped center embossed diaphragm (FCED) geometry has been proposed to modify in diaphragm-based Fabry-Perot fiber optic pressure sensors (FP-FOPS). The proposed FCED geometry was obtained by adding a pillar between the mesa and diaphragm. Before the simulation analysis of FCED, we derived mathematical equations of attenuation factor widening the acceptance radius. The attenuation factor is defined to understand sensor loss, which is neglected in the literature. With this derived formula, the light reflected from the deflected diaphragm and the light unguided in the fiber was detected. Since the deformation angle is zeroized in the FCED structures, the sensor loss due to the attenuation factor is eliminated. All the incident light being re-guided in the fiber. With FCED design's help, the decreasing sensitivity in the center embossed diaphragms (CED) has been prevented. Moreover, the deviation of the frequency response of FCED remains lower than 1% compared with the results of conventional diaphragms. As a result, it produces a more stable sensor, and the FCED structure is less affected by manufacturing errors. The researchers can benefit from the use of our presented results when designing and producing new diaphragm-based FP-FOPS.
Fabrication and characterization of printed phototransistors based on monochalcogenide inks
(Amer Chemical Soc, 2023-04-04) Muehleisen, Wolfgang; Roshanghias, Ali; AYDEMİR, UMUT; Odacı, Cem; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Elektrik ve Elektronik Bölümü.; 0000-0001-5396-4610; IXW-8105-2023
Two-dimensional (2D) layered semiconductors of Group-III monochalcogenides have gained increasing attention in photonics and electronics. The fabrication of large-scale, inexpensive inks which can be used in printed electronics applications is facilitated by the solution processing of 2D materials. In this study, gallium sulfide (GaS)-, gallium selenide (GaSe)-, and gallium telluride (GaTe)-loaded inks were synthe-sized and implemented to fabricate phototransistors on SiO2\Si substrates. To explore the printed device performances, several color illuminations were applied to the printed phototransistor, and the mobility, photoresponsivity, and external quantum efficiency parameters were compared. Under red-light illumination, the mobility of a GaTe nanoparticle-based phototransistor reached 7.456 cm2 V-1 s-1. The responsivity of the GaTe-based phototransistor was found to be the highest, with the value of 9.52 A W-1 under green light illumination. However, GaSe-based phototransistors gave the highest EQE value of 2482 (%) under blue light illumination with the mobility of 7.04 cm2 V-1 s-1. This study demonstrates that printable Group-III monochalcogenide inks can be synthesized with desired properties for use in printed electronic applications.
The electrical properties of au/PTCDA/n-si diodes with electron beam irradiated PTCDA interfacial layer
(Gazi Univ, 2019-06-01) Aydemir, Umut; AYDEMİR, UMUT; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; 0000-0001-5396-4610; V-2845-2018; IXW-8105-2023
In this work, it is aimed to improve the device performance of traditional Au/n-Si Schottky Diodes (SDs) with an innovative approach using the irradiated PTCDA interfacial layer. For this reason, first PTCDA powders were irradiated with different electron beam (E-Beam) doses of 30kGy, 60kGy and 100kGy and the results were analyzed by FTIR method. Unirradiated and irradiated PTCDA powders with E-Beam were evaporated on n-Si substrate via organic evaporator. Current-Voltage (I-V) characteristics of unirradiated and irradiated Au/PTCDA/n-Si SDs with PTCDA interfacial layers irradiated with different E-Beam doses of 30kGy, 60kGy and 100kGy were carried out between +/- 3V at room temperature. The ideality factor (n), Schottky barrier height (Phi(Bo)), rectification ratio (DO), series resistance (R-s) and shunt resistance (R-sh) of devices were calculated from current-voltage (I-V) results. It is experimentally seen that performance of Au/PTCDA/n-Si SD irradiated with 30 kGy has better results when we compared unirradiated Au/PTCDA/n-Si SD. It has been observed that the I-V characteristics of the Au/PTCDA/n-Si SD are highly influenced by irradiation and the device performance can be improved with appropriate irradiation dose.
The surface plasmon resonance-based fiber optic sensors: A theoretical comparative study with 2d tmdc materials
(Elsevier, 2021-05-01) Odac, Cem; Aydemir, Umut; AYDEMİR, UMUT; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Elektrik ve Elektronik Mühendisliği Bölümü.; 0000-0001-5396-4610; IXW-8105-2023
In this study, the surface plasmon resonance -based fiber optic sensor using two-dimensional (2D) TMDC materials covering the Au/Ag bimetallic layer has been reported. Since MoS2, MoSe2, WS2, and WSe2 are the most popular ones, they are constructed as the resonant layer of the sensor. The layer -dependencies and heterostructures of the TMDC materials are examined for the determination of their effect on the performance of the SPR sensor. The performance parameters of the SPR sensor, the sensitivity, accuracy, and figure of merit, are calculated with the help of the MATLAB simulations. It is found out that considering the very small change in the refractive index of the sensing medium (0.0025), the monolayer MoSe2 has the highest sensitivity value of 8096 nm/RIU. In contrast, the monolayer WS2 has the highest accuracy and figure of merit values of 0.34 and 136.89 RIU-1, respectively. This study will be benefited for a better understanding of the performance of the SPR based fiber optic sensor depending on the number of layers of TMDC materials and based on their heterostructures.
Use of 2D In 2 Se 3 single crystal as a diaphragm material for fabry-perot fiber optic acoustic sensors
(Amer Scientific Publishers, 2019-04-01) Hayber, Sekip-Esat; Tabaru, Timucin-Emre; Aydemir, Umut; Saraçoğlu, Ömer-Galip; AYDEMİR, UMUT; Bursa Uludağ Üniversitesi; 0000-0001-5396-4610; IXW-8105-2023; V-2845-2018
The diaphragm-based sensor tip, which has a critical design in Fabry-Perot fiber optic acoustic sensor production, directly affects device performance. Fabry-Perot fiber optic acoustic sensors tip designs and investigations on different geometric dimensions and different diaphragm materials continue in the literature. In this study, it is predicted that graphene-like two-dimensional In2Se3 single crystal can be used for the diaphragm material which we report for the first time in the literature. Analytical calculations and numerical simulations have been carried out in order to use two-dimensional In2Se3 single crystals as diaphragm material for Fabry-Perot fiber optic acoustic sensors tip production. The calculation results of the Fabry-Perot fiber optic acoustic sensors tip we designed using In2Se3 single crystal are compared with conventional sensor tip made from Si, SiO2 and graphene as a diaphragm in the literature. Since In2Se3 crystal has a high refraction index, sensor visibility allows for long Fabry-Perot cavities, which creates alternative solutions where very short Fabry-Perot cavities are not possible. Another advantage of this feature is that the inner surface of the diaphragm does not need to be coated with reflective materials like gold, silver etc. Using the high density of In2Se3 crystals for diaphragm materials results in reducing the percentage of frequency in transitions from less dense to more dense environments. According to the simulation results, it is seen that it has high sensitivity of 64.12 nm/kPa and this is the result of having a low Young's modulus than other diaphragm materials like Si, SiO2, graphene of the same geometry reported in the literature. The calculation results were also obtained for other materials as 26.54 nm/kPa, 62.58 nm/kPa, and 4.57 nm/kPa for Si, SiO2 and graphene, respectively. The innovative diaphragm design proposed in this work for Fabry-Perot fiber optic acoustic sensors tip production has been advised alternative solutions when sensor sensitivity and visibility must be considered.