Showing 12 results for Atomic Force Microscope
Ardeshir Karami Mohammadi, Mohammad Abbasi,
Volume 13, Issue 13 (3-2014)
Abstract
In this paper, the effect of size of an atomic force microscope (AFM) with an assembled cantilever probe (ACP) on resonant frequencies and their sensitivities are investigated using the strain gradient elasticity theory. The proposed ACP comprises a horizontal microcantilever, an extension and a tip located at the free end of the extension, which make the AFM capable of scanning the sample sidewall. First, the governing differential equation of motion and boundary conditions for dynamic analysis are obtained by a combination of the basic equations of the strain gradient elasticity theory and Hamilton principle. Afterwards, the flexural resonant frequency and sensitivity of the proposed AFM microcantilever are obtained numerically. The results of the proposed method are compared with those of modified couple stress and classical beam theories. The comparison shows that the difference between the results predicted by the strain gradient elasticity theory with those obtained by couple stress and classical beam theories become significant when the horizontal cantilever thickness comes approximately close to the material length scale parameter.
Ardeshir Karami Mohammadi, Mohammad Abbasi,
Volume 14, Issue 11 (2-2015)
Abstract
In this study, the nonlinear vibration behavior of a dynamic atomic force microscope (DAFM) in the tapping mode is investigated. First, the governing differential equation of motion and boundary conditions for dynamic analysis are obtained by a combination of the basic equations of the modified couple stress theory and Hamilton principle. Regarding the nonlinear dynamics of the probe, perturbation technique has been used to solve the nonlinear equations. Afterwards, closed-form expressions for nonlinear frequency and effective nonlinear damping factor are derived. The effect of connection position of the tip on the vibration behavior of the microcantilever are also analyzed. The results obtained by couple stress theory are compared with those of classical beam theory. The results show that the nonlinear frequency and effective nonlinear damping factor are size dependant. According to the results, an increase in the equilibrium separation between the tip and the surface sample reduces the overall effect of van der Waals forces on the nonlinear frequency, but its effect on the effective nonlinear damping factor is negligible. The results also indicate that the change in the distance between tip and cantilever free end has a significant effect on the accuracy of the DAFM.
Amin Habibnejad Korayem, Moein Taheri, Moharam Habibnejad Korayem,
Volume 15, Issue 1 (3-2015)
Abstract
Nowadays one of the arguments that have been raised in the world of nanotechnologies is moving or manipulation nanoparticles. This discussion is important because the displacement of nanoparticles can make structurally different than what is currently available. So to achieve this goal, the atomic force microscope probe is used as manipulator. In this way, the use of nanoparticles by pulling or pushing on the surface, are displaced and brought to the desired point. If you apply too much force is needed, Nanoparticle Continued movement (sliding or rolling) after standing atomic force microscopy probes and away from the desired final. On the other hand, if the force is low, so that it can’t overcome the static friction force, Nanoparticles will be no movement. So finding the optimal force is important in nanomanipulation. In this paper, with using nanoparticle dynamic simulation, the governing equations on nanoparticle are derived and simulated during manipulation happen that they can be used to obtain the critical force and time for gold, yeast and platelets nanoparticles, in gaseous, water, alcohol, and plasma environments. By comparing the results obtained in this paper, it is concluded that the movement of particles in different biological environments starts later and by a force of higher magnitude relative to the gaseous medium.
Moein Taheri,
Volume 15, Issue 12 (2-2016)
Abstract
In nanomanipulation using atomic force microscopy, for the displacement of various micro/nanoparticles, calculation of accurate critical force and time of manipulation in order to not damage and precise manipulation of micro/nanoparticles, is necessary. To achieve this goal requires accurate modeling of kinematics and dynamics of a two-dimensional nanomanipulation that already has been done. In this paper, three-dimensional nanomanipulation modeling and simulation dynamic has been done for more simulation results closer to the results of real nanomanipulation. For this purpose, by taking a spherical shape for micro/nanoparticle, three-dimensional kinematic relations manipulation extracted. Then, JKR contact model for use in manipulation provided and rectangular beam stiffness equations derived in three dimensions. In the final stage of the modeling of the dynamics of the three-dimensional micro/nanoparticles to extract force equations and critical time manipulation obtained. Then the equations obtained by simulation, three-dimensional manipulation amount of force and critical time for both DNA and platelets biological particle is calculated. The results indicate start rolling motion of the particles studied before rolling around on the x-axis and y axis and z as well as the critical need for displacement of particles of the platelet-derived DNA.
Yasser Nikou, Behrooz Rezaie, Zahra Rahmani,
Volume 16, Issue 1 (3-2016)
Abstract
In this paper, an intelligent robust controller is proposed for a class of nonlinear systems in presence of uncertainties and bounded external disturbances. The proposed method is based on a combination of terminal sliding mode control and adaptive neuro-fuzzy inference system with bee’s algorithm training. For this purpose, a sliding surface is firstly designed based on terminal sliding control method. This sliding surface is considered as input for the intelligent controller which is an adaptive neuro-fuzzy inference system and using it, terminal sliding mode control law without the switching part is approximated. In the proposed method, an intelligent bee’s algorithm is also used for updating the weights of the adaptive neuro-fuzzy inference system. Compared with fast terminal sliding mode control, the proposed controller provides advantages such as robustness against uncertainty and disturbance, simplicity of controller structure, higher convergence speed compared with similar conventional methods and chattering-free control effort. The method is applied to an atomic force microscope for nano manipulation. The simulation results show the robustness and effectiveness of the proposed method.
Moein Taheri,
Volume 16, Issue 10 (1-2017)
Abstract
Nowadays, atomic force microscopy has widely attracted researchers’ attention in manufacturing of micro/nano equipment. For this purpose, the displacement and manipulation equations for micro/nano-particle are essential. Although surface forces such as friction and adhesion are ignorable in macro scale, increased surface to volume ratio in micro/nano scale makes them very important. Various friction models have been used for two-dimensional manipulation in previous works. In this paper, HK friction model has been used to model and simulate three dimensional manipulation dynamically in order to have closer results to real manipulation. For this purpose, the important friction models have been studied and developed to use in micro/nano scale. Then, three-dimensional manipulation equations have been obtained and stiffness coefficient matrix for beam is extracted and all these equations have been combined to calculate the critical force and time of manipulation. Finally, simulation of obtained equations was used to calculate the critical force and time values of the three-dimensional manipulation for gold particle using HK friction model. The results indicate that rolling starts around x-axis before y-axis, and sliding starts along y-axis before x-axis.
Moharam Habibnejad Korayem, Amin Habibnejad Korayem, Moein Taheri, Saeed Rafee Nekoo,
Volume 16, Issue 11 (1-2017)
Abstract
Nowadays, movement of micro/nano particles has been attracted considerable attention to manufacturing different devices in micro/nano scale and medical and biological applications. Atomic Force Microscope Probe is widely being used for precise small scale movements. During nano-manipulation, micro/nano particles can be moved to a desired destination with high accuracy using Atomic Force Microscope while in contact mode with precise probe control. In this article, by selecting a proper amount of torque applied to the probe tip, deviation from the center and movement of probe have been investigated to assure the contact between the probe and micro/nano particle. Different liquid environments (water, alcohol, and plasma) with different micro/nano particles including biological and non-biological have been used for this investigation. In addition, using sliding mode control, Atomic Force Microscope Probe was used in different environments such as water, alcohol, and plasma. Obtained results showed that the time needed to control different micro/nano particles in plasma was shorter than that of in water; also the time needed in water was shorter than that of in alcohol.
Behzad Saeedi, Ramin Vatankhah,
Volume 17, Issue 12 (2-2018)
Abstract
In this study, nonlinear behavior of an atomic force microscopes (AFM) immersed in acetone, water, carbon tetrachloride (CCl4), and 1-butanol is investigated using non-classical strain gradient theory. In this theory, the size effect of system is taking into account by means of material length scale parameter. The nonlinear behavior of the AFM is due to the nonlinearity of the AFM tip–sample interaction caused by the Van der Waals attraction/repulsion force. Behavior of micro beam immersed in liquid is completely different with its behavior in air and vacuum due to the existence of hydrodynamic force. The Resonant frequencies, mode shapes, governing nonlinear partial and ordinary differential equations (PDE and ODE) of motion, stability analysis, boundary conditions, potential function and phase-plane of the system are obtained analytically in the present study. Furthermore, the results are compared with the one obtained by the modified couple stress theory. For this purpose, the AFM and the probe at the free end of micro beam are modeled as a lumped mass. The fixed end of micro beam is excited by piezoelectric element. The nonlinear PDE of motion is derived based on Euler-Bernoulli theory by employing the Hamilton principle. The Galerkin method is utilized to gain the governing nonlinear ODE of motion and the obtained ODE is analytically solved by means of perturbation techniques.
M. Molavian Jazi, M. Ghayour , S. Ziaei-Rad , E. Maani,
Volume 19, Issue 4 (4-2019)
Abstract
The atomic force microscope (AFM) determines the topography of surfaces in nano scale based on the changes in the exited micro-cantilever’s dynamic characteristics. Therefore, it is essential to simulate and predict more accurately the dynamic behavior of cantilever beams for use in design and fabrication of AFM. Based on the experimental observations, in contrast to the classic theory, the normalized stiffness of structures is not constant with the reduction of dimensions in micro and nano scales. This change, which can be either softness or stiffness, results in size-dependent behavior, non-classic continuum theories. This paper studies the effect of size on the dynamic behavior of AFM based on modified couple stress theory, and compares the results with those obtained from classic theory. The nonlinear partial differential governing equation of the system is derived, considering intermolecular and hydrodynamic forces, based on the modified couple stress theory. By applying Galerkin projection method, partial differential equations are transformed into ordinary equations and the discrete system is extracted. It is shown that considering size effect leads to enlargement of expected working domain of AFM, and also predicted amplitude and frequency of oscillations decreases and increases, respectively. Moreover, two theories predict different start point of bi-stability region. Solution approach is verified by comparing the results with two degrees-of-freedom model and analogue equations method. Furthermore, effect of hydrodynamic forces of fluid on dynamic behaviour of AFM is investigated.
H. Karamad, S. Maleki, A. Andakhshideh,
Volume 19, Issue 12 (12-2019)
Abstract
In this paper, an atomic force microscope is modeled based on non-classical nonlocal theory and nonlinear vibration of the system is analyzed and controlled. In this modeling, the Hamilton principle is used to derive the governing equation of Euler-Bernoulli nanocantilever based on the Eringen nonlocal elasticity theory considering Von-Karman geometric non-linearity. In the next step, using the Galerkin method, the governing dynamics differential equation of the atomic force microscope is obtained in the presence of attractive and repulsive van der Waals forces. The governing nonlinear equation is solved by employing multiple time scales method, and primary and secondary resonance of the atomic force microscope is studied. In this regard, the frequency response and excitation amplitude curves of primary, superharmonic and subharmonic resonances are plotted for different values of the nonlocal parameter. Accordingly, it is shown that primary, superharmonic and subharmonic resonances of atomic force microscope are significantly affected by the nonlocal parameter. The results show that the use of nonlocal theory is a fundamental necessity for analyzing nonlinear vibrations of the atomic force microscope. Then, in addition to dynamic analysis, the chaotic vibrations are completely controlled and removed in the nonlocal model of the atomic force microscope by designing and implementing the robust adaptive fuzzy controller. For this task, the robust adaptive fuzzy controller which is considered as a powerful method of chaos controlling is used in the nonlocal model of atomic force microscope. The obtained results are used in the design and control process of the atomic force microscope.
, A_sadeghi@damavandiau.ac.ir,
Volume 21, Issue 1 (1-2021)
Abstract
| In this paper, the non-linear dynamic behavior of immersed AFM micro cantilever in liquid has been modeled. To increase the accuracy of the theoretical model, all necessary details for cantilever and sample surface have been taken into account. As for the theoretical model, the Timoshenko beam theory which takes the rotatory inertia and shear deformation effects into consideration has been adopted. For modeling the vibrational system, cantilever thickness, cantilever length and breadth, the angle between cantilever and sample surface, normal contact stiffness, lateral contact stiffness, tip height, breadth taper ratio, height taper ratio, time parameter and viscosity of the liquids have been considered. Differential quadrature method (DQM) has been used for solving the differential equations. During the investigation, the softening behavior was observed for all cases. Here, water, methanol, acetone and carbon tetrachloride has been supposed as immersion environments. Results show that increasing the liquid density reduces the resonant frequency. Time variable does not have any considerable effect on the non-linear resonant frequency. Theoretical modeling has been compared for a rectangular AFM cantilever with experimental works in both of the contact and non-contact modes in air and water environments. Results show good agreement. |
Volume 22, Issue 159 (4-2025)
Abstract
Image processing is an essential tool to evaluate food structure. Image processing includes two-dimensional (2D) images of surfaces and sections, such as those seen under a microscope, and three-dimensional (3D) images of internal structures, such as those obtained by confocal microscopy, computed tomography, and magnetic resonance imaging. This research used image processing to determine the hardness and compressibility of edible biofilms impregnated with nanoemulsion. Gum arabic-gelatin (PG) (1:1) edible film containing thyme essential oil (Zataria multiflora Boiss) was prepared with Pickering emulsion (1 and 4 g/100 g). Scanning electron microscope and atomic force microscope images were prepared from the films. The AFM and image analysis results showed that increasing the essential oil decreases the compression rate and the surface roughness increases.
