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Modeling of eccentric nanoneedle in trolling-mode atomic force microscope
, Article Microscopy Research and Technique ; Volume 84, Issue 4 , 2021 , Pages 639-655 ; 1059910X (ISSN) ; Sajjadi, M ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Limitations on installation of a standard TR-AFM nanoneedle can have unpredictable effects on dynamics of system. Therefore, it is crucial to pay close attention to the position and geometry of mounted nanoneedle when deriving the mathematical model. During TR-AFM fabrication process, the nanoneedle may not always deposit precisely at the middle of AFM tip, which would result in coupled bending-torsion modes in the dynamical operation of system. In this paper, we investigate the effect of eccentric nanoneedle in dynamic response of TR-AFM. To address this issue, a continuous mathematical model is developed. This model accounts for eccentric nanoneedle which can address the couplings in...
Modeling of eccentric nanoneedle in trolling-mode atomic force microscope
, Article Microscopy Research and Technique ; 2020 ; Sajjadi, M ; Sharif University of Technology
Wiley-Liss Inc
2020
Abstract
Limitations on installation of a standard TR-AFM nanoneedle can have unpredictable effects on dynamics of system. Therefore, it is crucial to pay close attention to the position and geometry of mounted nanoneedle when deriving the mathematical model. During TR-AFM fabrication process, the nanoneedle may not always deposit precisely at the middle of AFM tip, which would result in coupled bending-torsion modes in the dynamical operation of system. In this paper, we investigate the effect of eccentric nanoneedle in dynamic response of TR-AFM. To address this issue, a continuous mathematical model is developed. This model accounts for eccentric nanoneedle which can address the couplings in...
Effect of annealing on the micromorphology and corrosion properties of Ti/SS thin films
, Article Superlattices and Microstructures ; Volume 146 , 2020 ; Arman, A ; Jurečka, S ; Korpi, A. G ; Mwema, F ; Luna, C ; Sobola, D ; Kulesza, S ; Shakoury, R ; Bramowicz, M ; Ahmadpourian, A ; Sharif University of Technology
Academic Press
2020
Abstract
Ti and TiN thin films were deposited by means of electron beam evaporation on stainless steel substrates, and subsequently annealed at different temperatures (650, 750 and 850 °C) in a nitrogen atmosphere. The surface morphology of the films studied by atomic force microscopy (AFM), was found to exhibit specific multifractal properties depending on the annealing temperature. It turned out that the width of the multifractal singularity spectra, f(α), decreased as the annealing temperature increased up to 750 °C, but it increased when the temperature was kept at 750 and 850 °C accompanied by the rapid development of the surface objects. The generalized fractal dimension followed a similar...
Stereometric analysis of TiO2 thin films deposited by electron beam ion assisted
, Article Optical and Quantum Electronics ; Volume 52, Issue 5 , 2020 ; Arman, A ; Ţălu, Ş ; Dastan, D ; Luna, C ; Rezaee, S ; Sharif University of Technology
Springer
2020
Abstract
The micromorphology and semiconductor properties of TiO2 thin films growth using different ion beam energies have been finely analyzed using atomic force microscopy (AFM), ultra-violet visible (UV–visible) spectroscopy and stereometric analysis. The AFM measurements and surface stereometric analysis are essential for the accurate characterization of the 3-D surface topographic features and allow the determination of the 3-D surface texture parameters that influence the optical properties of the material. The samples were divided into four groups to discuss the obtained results, according to the ion beam energy applied in the sample preparation. The results obtained from experimental...
On the nonlinear dynamics of trolling-mode AFM: analytical solution using multiple time scales method
, Article Journal of Sound and Vibration ; Volume 423 , 9 June , 2018 , Pages 263-286 ; 0022460X (ISSN) ; Nejat Pishkenari, H ; Vossoughi, G ; Sharif University of Technology
Academic Press
2018
Abstract
Trolling mode atomic force microscopy (TR-AFM) has resolved many imaging problems by a considerable reduction of the liquid-resonator interaction forces in liquid environments. The present study develops a nonlinear model of the meniscus force exerted to the nanoneedle of TR-AFM and presents an analytical solution to the distributed-parameter model of TR-AFM resonator utilizing multiple time scales (MTS) method. Based on the developed analytical solution, the frequency-response curves of the resonator operation in air and liquid (for different penetration length of the nanoneedle) are obtained. The closed-form analytical solution and the frequency-response curves are validated by the...
Finite element modeling of trolling-mode AFM
, Article Ultramicroscopy ; Volume 189 , 2018 , Pages 24-38 ; 03043991 (ISSN) ; Nejat Pishkenari, H ; Vossoughi, G
Elsevier B.V
2018
Abstract
Trolling mode atomic force microscopy (TR-AFM) has overcome many imaging problems in liquid environments by considerably reducing the liquid-resonator interaction forces. The finite element model of the TR-AFM resonator considering the effects of fluid and nanoneedle flexibility is presented in this research, for the first time. The model is verified by ABAQUS software. The effect of installation angle of the microbeam relative to the horizon and the effect of fluid on the system behavior are investigated. Using the finite element model, frequency response curve of the system is obtained and validated around the frequency of the operating mode by the available experimental results, in air...
Effects of tip mass and interaction force on nonlinear behavior of force modulation fm-afm cantilever
, Article Journal of Mechanics ; Volume 33, Issue 2 , 2017 , Pages 257-268 ; 17277191 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2017
Abstract
Influences of the tip mass, excitation mode of Frequency Modulated Atomic Force Microscope (FM-AFM) on the resonance frequency shift in force modulation (FM) mode are studied. Governing equations of motion are determined based on Timoshenko beam model with concentrated end mass. Approach point and base amplitude are set such that the FM-AFM remains just in FM mode. Either the linearized and nonlinear Derjaguin-Muller-Toporov (DMT) model are investigated. Then frequency shifts are determined for various interaction force regimes. It is showed the effect of tip mass on frequency shift is significant even for small tips. Nonlinear model shows lower frequency shifts in comparison with linearized...
Global sensitivity analysis of backside coating parameters on dynamic response of AM-AFM
, Article Mechanika ; Volume 23, Issue 2 , 2017 , Pages 282-290 ; 13921207 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Kauno Technologijos Universitetas
2017
Abstract
Influence of backside coating parameters on dynamic response of AM-AFM is modeled. Timoshenko based beam model is used and the general nonlinear interaction force is enclosed. The coupled ODEs of motion are achieved. The mode shapes are determined for coated cantilever and the natural frequency of each mode is validated with experimental results. It is showed a shorter cantilever with tip mass have better accuracy and inelastic and massless assumptions are not proper choice for modelling of the coating. The assumed mode method is used to determine time response of system for faraway and scanning condition of AM-AFM. Amplitude of response is calculated by FFT of time domain. Sensitivity...
Effects of tip mass and interaction force on nonlinear behavior of force modulation FM-AFM cantilever
, Article Journal of Mechanics ; 2016 , Pages 1-12 ; 17277191 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2016
Abstract
Influences of the tip mass, excitation mode of Frequency Modulated Atomic Force Microscope (FM-AFM) on the resonance frequency shift in force modulation (FM) mode are studied. Governing equations of motion are determined based on Timoshenko beam model with concentrated end mass. Approach point and base amplitude are set such that the FM-AFM remains just in FM mode. Either the linearized and nonlinear Derjaguin-Muller-Toporov (DMT) model are investigated. Then frequency shifts are determined for various interaction force regimes. It is showed the effect of tip mass on frequency shift is significant even for small tips. Nonlinear model shows lower frequency shifts in comparison with linearized...
Dynamics of the nanoneedle probe in trolling mode AFM
, Article Nanotechnology ; Volume 26, Issue 20 , April , 2015 ; 09574484 (ISSN) ; Pishkenari, H. N ; Keramati, R ; Minary Jolandan, M ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, presents major drawbacks for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced 'Trolling mode' (TR-mode) AFM resolves this complication by using a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such a cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle-liquid interface on the performance of the AFM, including the imaging capability in liquid
Atomic interactions between metallic tips and surfaces in NC-AFM
, Article Journal of Physics D: Applied Physics ; Volume 48, Issue 12 , February , 2015 ; 00223727 (ISSN) ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
In this paper, the atomic-scale interactions between metallic tips and samples in noncontact atomic force microscopy (NC-AFM) are studied using molecular dynamics simulations. The effects of the tip and sample materials, the surface plane direction and the lateral position of the tip with respect to the sample, on the interaction force and the dissipated energy, are investigated. The simulations conducted demonstrate that, generally, we can classify the possible outcomes for the dynamics due to the tip-surface interactions into four major categories. The first category includes all cases in which there are no considerable instabilities in tip-surface interactions, leading to negligible...
Study of Biomolecules Imaging Using Molecular Dynamics Simulations
, Article Nano ; Volume 10, Issue 7 , October , 2015 ; 17932920 (ISSN) ; Nejat Pishkenari, H ; Moosavi, A ; Meghdari, A ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2015
Abstract
The process of imaging a biomolecule by atomic force microscope (AFM) is modeled using molecular dynamics (MD) simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the noncontact mode of AFM (NC-AFM) is employed as the operating mode. The biosample is scanned using a carbon nanotube (CNT) as the AFM probe. CNTs because of their small diameter, high aspect ratio and high mechanical resistance attract many attentions for imaging purposes. The tip-sample interaction is simulated by the MD method. The protein, which has been considered as the biomolecule, is ubiquitin and a...
Thermo- and pH-sensitive dendrosomes as bi-phase drug delivery systems
, Article Nanomedicine: Nanotechnology, Biology, and Medicine ; Volume 9, Issue 8 , 2013 , Pages 1203-1213 ; 15499634 (ISSN) ; Fard, A. K ; Abedi, F ; Chegeni, B. K ; Bani, F ; Sharif University of Technology
2013
Abstract
Fully supramolecular dendrosomes (FSD) as bi-phase drug delivery systems are reported in this work. For preparation of FSD, amphiphilic linear-dendritic supramolecular systems (ALDSS) have been synthesized by host-guest interactions between hyperbranched polyglycerol having β-cyclodextrin core and bi-chain polycaprolactone (BPCL) with a fluorescine focal point. Self-assembly of ALDSS in aqueous solutions led to FSD. They were able to encapsulate paclitaxel with a high loading capacity. The dendrosome-based drug delivery systems were highly sensitive to pH and temperature. They were stable at 20-37. °C and pH7-8, but dissociated and released drug at temperatures lower than 20. °C or higher...
Surface roughness analysis of hydrophilic SiO2/TiO 2/glass nano bilayers by the level crossing approach
, Article Physica A: Statistical Mechanics and its Applications ; Volume 392, Issue 9 , 2013 , Pages 2175-2181 ; 03784371 (ISSN) ; Reza Rahimi Tabar, M ; Moshfegh, A. Z ; Sharif University of Technology
2013
Abstract
The effect of etching time on the statistical properties of hydrophilic surfaces of SiO2/TiO2/glass nano bilayers has been studied using atomic force microscopy (AFM) and a stochastic approach based on a level crossing analysis. We have created rough surfaces of the hydrophilic SiO 2/TiO2 nano bilayer system by using 26% potassium hydroxide (KOH) solution. Measuring the average apparent contact angle allowed us to assess the degree of hydrophilicity, and the optimum condition was determined to be 10 min etching time. A level crossing analysis based on AFM images provided deeper insight into the microscopic details of the surface topography. With different etching times, it has been shown...
Development of nanostructured porous TiO2 thick film with uniform spherical particles by a new polymeric gel process for dye-sensitized solar cell applications
, Article Electrochimica Acta ; Volume 89 , February , 2013 , Pages 90-97 ; 00134686 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
2013
Abstract
A novel simple synthetic procedure for fabrication of high surface area nanostructured TiO2 electrode with uniform particles for photovoltaic application is reported. Modifying the TiO2 particulate sol by pH adjustment together with employment of a polymeric agent, so-called polymeric gel process, was developed. The polymeric gel process was used to deposit nanostructured thick electrode by dip coating incorporated in dye-sensitized solar cells (DSSCs). X-ray diffraction (XRD) analysis revealed that deposited film was composed of primary nanoparticles with average crystallite size in the range 21-39 nm. Field emission scanning electron microscope (FE-SEM) images showed that deposited film...
Characterization of polymeric membranes for membrane distillation using atomic force microscopy
, Article Desalination and Water Treatment ; Volume 51, Issue 31-33 , 2013 , Pages 6003-6008 ; 19443994 (ISSN) ; Bastani, D ; Kargari, A ; Tabatabaei, M ; Sharif University of Technology
Taylor and Francis Inc
2013
Abstract
As membrane distillation (MD) is an under-developed separation process, specific membranes for MD applications are not yet commercially available. Therefore, microporous polymeric membranes made of hydrophobic materials fabricated for microfiltration purposes are usually used for MD applications. Characterization of such kind of membranes is important in order to achieve a better in-depth understanding of their performance and to fabricate specific membranes for MD process. One of the emerging characterization methods is atomic force microscopy (AFM) analysis. AFM is a newly developed high-resolution method that is useful for studying the surface topography of various types of membranes, and...
Optimal sliding mode control for Atomic Force Microscope tip positioning during nano-manipulation process
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 2285-2296 ; 10263098 (ISSN) ; Mahboobi, S. H ; Vakilzadeh, M. K ; Alasty, A ; Meghdari, A ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
This research presents two-dimensional controlled pushing-based nanomanipulation using an Atomic Force Microscope (AFM). A reliable control of the AFM tip position is crucial to AFM-based manipulation since the tip can jump over the target nanoparticle causing the process to fail. However, detailed modeling and an understanding of the interaction forces on the AFM tip have a central role in this process. In the proposed model, the Lund-Grenoble (LuGre) method is used to model the dynamic friction force between the nanoparticle and the substrate. This model leads to the stick-slip behavior of the nanoparticle, which is in agreement with the experimental behavior at nanoscale. Derjaguin...
Effect of chemical substitution on the morphology and optical properties of Bi1-xCaxFeO3 films grown by pulsed-laser deposition
, Article Journal of Materials Science: Materials in Electronics ; Volume 24, Issue 1 , 2013 , Pages 248-252 ; 09574522 (ISSN) ; Mahdavi, S. M ; Nemati, A ; Sharif University of Technology
2013
Abstract
The morphological characteristics as well the optical properties of Ca-doped BiFeO3 films grown by pulsed-laser deposition technique have been investigated. AFM images revealed that calcium has a radical effect on the surface features of BiFeO3 films. By utilizing spectrophotometer, transmission behaviour of the films was investigated. Local IV characteristics of the films disclosed about three orders of magnitude enhancement concerning electrical conductivity through Ca doping. X-ray photoelectron spectroscopy results revealed that Ca can reduce the valence state of iron in the compound
Tailoring of morphology and crystal structure of nanomaterials in MgO-TiO 2 system by controlling Mg:Ti molar ratio
, Article Journal of Sol-Gel Science and Technology ; Volume 64, Issue 1 , October , 2012 , Pages 135-144 ; 09280707 (ISSN) ; Fray, D. J ; Sharif University of Technology
Springer
2012
Abstract
The morphological manipulation and structural characterisation of TiO 2-MgO binary system by an aqueous particulate sol-gel route were reported. Different crystal structures including pure MgTiO 3, mixtures of MgTiO 3 and TiO 2 and mixtures of MgTiO 3 and Mg 2TiO 4 were tailored by controlling Mg:Ti molar ratio and annealing temperatures as the processing parameters. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that all compounds crystallised at the low temperature of 500 °C. Furthermore, it was found that the average crystallite size of the compounds depends upon the Mg:Ti molar ratio as well as the annealing temperature, being in the range 3-5 nm at...
Tip and sample flexibility effects on tapping mode (amplitude modulation) AFM measurements
, Article Micro and Nano Letters ; Volume 6, Issue 12 , December , 2011 , Pages 1023-1028 ; 17500443 (ISSN) ; Meghdari, A ; Sharif University of Technology
2011
Abstract
This Letter is devoted to the investigation of the tip, substrate and particle flexibility effects on the elastic deformation, the maximum repulsive force and the topography images in tapping mode (amplitude modulation) atomic force microscopy (TM-AFM). Several quantitative comparisons among the different models are presented and the effects of the elastic deformations on TM-AFM measurement are investigated