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    Characterization and analysis of motion mechanism of electroactive chitosan-based actuator
    (Elsevier Sci Ltd, 2018) Altinkaya, Emine; Seki, Yoldas; Cetin, Levent; Gurses, Baris Oguz; Ozdemir, Okan; Sever, Kutlay; Sarikanat, Mehmet
    In order to analyze the bending mechanism of the electroactive chitosan- based actuator, different amounts of poly(diallyldimethylammonium chloride) (PDAD) were incorporated in chitosan solution. The effects of PDAD concentration on electromechanical performance of chitosan actuator were investigated under various excitation voltages. With the incorporation of PDAD into chitosan solution, crosslinked chitosan film acts as an actuator showing a considerable displacement behavior. However it can be noted that higher incorporation of PDAD into chitosan solution decreased the performance of the actuators. Thermal, viscoelastic, and crystallographic properties of the chitosan films were examined by thermogravimetric analysis, dynamic mechanical analysis, and X- ray diffraction analysis, respectively. The effect of incorporation of PDAD in chitosan- based film on morphological properties of chitosan film was determined by scanning electron microscopy. It was observed that the films involving PDAD have larger pore size than the PDAD free film.
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    Electroactive behavior of graphene nanoplatelets loaded cellulose composite actuators
    (Elsevier Sci Ltd, 2015) Sen, Ibrahim; Seki, Yoldas; Sarikanat, Mehmet; Cetin, Levent; Gurses, Bans Oguz; Ozdemir, Okan; Yilmaz, Ozgun Cem
    In this study, graphene nanoplatelets (0.10, 0.25, and 0.50 wt.%) were loaded into cellulose matrix to improve electroactive performance of cellulose-based composite actuators. Firstly, cellulosic films were produced by dissolving microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride. Afterwards, graphene loaded cellulosic films were fabricated and gold leaf was coated on both surfaces of graphene loaded cellulose-based films. The changes in crystallographic properties and chemical functional groups of cellulose were investigated by X-ray diffraction and Fourier transform infrared analyses, respectively. Besides, thermal stability, electrical conductivity, and morphological properties of the films were examined by thermogravimetric analysis, electrical conductivity measurement, and scanning electron microscopy, respectively. The tensile strength and the Young's modulus of the films and actuators were also determined by tensile tests. The electroactive characteristics were analyzed under DC excitation voltages of 3 V, 5 V and 7 V. The time responses were evaluated via proposed experimental data based model. The performances of the actuators were compared in terms of maximum tip displacement, minimum tip displacement and time constant. (C) 2014 Elsevier Ltd. All rights reserved.
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    Electromechanical performance of chitosan-based composite electroactive actuators
    (Elsevier Sci Ltd, 2016) Altinkaya, Emine; Seki, Yoldas; Yilmaz, Ozgun Cem; Cetin, Levent; Ozdemir, Okan; Sen, Ibrahim; Sever, Kutlay
    A novel chitosan-based electroactive actuator was fabricated by using chitosan, N, N'-methylenebisacrylamide (MBA), poly (diallyldimethylammonium chloride), and gold metal. The constructive effect of crosslinker to the actuator performance was investigated by using various amounts of MBA. The chitosan-based film samples were characterized using Fourier transform infrared analyses, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy analysis, and tensile test. The viscoelastic properties of films were determined by dynamic mechanical analysis. The motion and force generation capabilities and the repeatability of the actuators were also investigated under electrical stimuli up to 21 V. The suitability of the prepared chitosan-based films to be used as actuator for soft robotic applications is verified experimentally. (C) 2016 Elsevier Ltd. All rights reserved.
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    Improvement of the electromechanical performance of carboxymethylcellulose-based actuators by graphene nanoplatelet loading
    (Springer, 2015) Ozdemir, Okan; Karakuzu, Ramazan; Sarikanat, Mehmet; Seki, Yoldas; Akar, Emine; Cetin, Levent; Yilmaz, Ozgun Cem
    In this article, the effects of graphene loading (0.1, 0.2, 0.3 wt%) on both the electromechanical and mechanical properties of carboxymethylcellulose (CMC)-based actuators were investigated. CMC-based graphene-loaded actuators were prepared by using 1-butyl-3-methylimidazolium bromide. The synthesized graphene-loaded actuators were characterized by Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile tests. Electromechanical properties of the actuators were obtained under DC excitation voltages of 1, 3, 5, and 7 V with a laser displacement sensor. According to the obtained results, the ultimate tensile strength of CMC-based actuators containing 0.3 wt% graphene was higher than that of unloaded actuators by approximately 72.8 %. In addition, the Young's modulus value of the graphene-loaded actuators increased continuously with increasing graphene content. Under a DC excitation voltage of 5 V, the maximum tip displacement of 0.2 wt% graphene-loaded actuators increased by about 15 % compared to unloaded actuators.
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    Investigation of the effects of PWM parameters on ionic polymer metal composite actuators
    (Iop Publishing Ltd, 2014) Yilmaz, Ozgun Cem; Cetin, Levent; Gurses, Baris Oguz; Sen, Ibrahim; Ozdemir, Okan; Sarikanat, Mehmet; Seki, Yoldas
    The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafion-based ionic polymer metal composite (IPMC) actuator response were found out. The first set of experiments was designed to observe the actuator response when the actuators were biased with constant DC voltages. These experimental results were exploited to build an experimental data based dynamic model. The model and these results were also used as references to evaluate the experimental results in the proceeding experiments. The second set of experiments was designed to observe the actuator response when the DC square wave signals at different frequencies (0 to 1000 Hz) were applied. The third set of experiments was designed to observe the actuator response when the PWM signals at different magnitudes (6, 8 and 10 V) were applied. It is observed that back relaxation reduces with increasing frequency, but after a certain frequency value, it remains approximately constant. It is seen that the input output relationship of the actuators are linear only for a range of PWM signal magnitudes. The observations in both the PWM frequency and the magnitude experiments indicated that the performance of the Nafion-based IPMC actuator could be improved by selecting a magnitude of PWM signals between 6-8 Volts and by selecting a frequency between 400-1000 Hz.
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    The effect of gold electrode thicknesses on electromechanical performance of Nafion-based Ionic Polymer Metal Composite actuators
    (Elsevier Sci Ltd, 2019) Yilmaz, Ozgun Cem; Sen, Ibrahim; Gurses, Baris Oguz; Ozdemir, Okan; Cetin, Levent; Sarikanat, Mehmet; Seki, Yoldas
    The effect of gold electrode thickness (10, 27, 45, 67 and 80 nm) on the electromechanical performance of Nafion-based Ionic Polymer Metal Composite (IPMC) actuators was investigated in this study. The mechanical, morphological, electrical properties and electroactive behaviors of IPMC under direct current voltage (DC) and alternating voltage (AC) were examined. The tip displacement and maximum blocking force of actuators under various electrical stimulations were measured. In order to define transient response characteristics and quasi steady state value of the actuators, DC excitations of 1, 3, 5, 7 and 9 V were used. Besides, to define bandwidth of the actuator samples, square wave excitation with magnitudes of 3, 5, and 7 V and frequencies of 0.1, 0.25, 0.5, 1, and 2 Hz were applied to actuator samples. The actuator having a gold electrode thickness of 45 nm produced maximum tip displacement among all actuators for all excitation DC voltages. In the square wave experiments, the higher cutoff frequencies were observed for the actuators with 27 and 45 nm electrode thicknesses. The blocking force of IPMC increased with increasing gold electrode thickness from 10 nm to 45 nm and decreased with increasing gold electrode thickness from 45 nm to 80 nm.