Increasing the Image Contrast of Atomic Force Microscope by Using Improved Rectangular Micro Cantilever

2011 ◽  
Vol 110-116 ◽  
pp. 4888-4892
Author(s):  
Ali Sadeghi
Keyword(s):  
Atomic Force Microscope ◽  
Contact Stiffness ◽  
Beam Theory ◽  
Flexural Vibration ◽  
Sample Surface ◽  
Limited Range ◽  
Image Contrast ◽  
Atomic Force ◽  
Afm Cantilever ◽  
Micro Cantilever

The resonant frequency of flexural vibrations for an atomic force microscope (AFM) cantilever has been investigated using the Euler-Bernoulli beam theory. The results show that for flexural vibration the frequency is sensitive to the contact position, the first frequency is sensitive only to the lower contact stiffness, but high order modes are sensitive in a larger range of contact stiffness. By increasing the height H, for a limited range of contact stiffness the sensitivity to the contact stiffness increases. This sensitivity controls the image contrast, or image quality. Furthermore, by increasing the angle between the cantilever and sample surface, the frequency decreases.

Optimization of First Mode Sensitivity of V-Shaped AFM Cantilever Using Genetic Algorithm Method

2009 ◽  
Author(s):  
S. A. Moeini ◽  
M. H. Kahrobaiyan ◽  
M. Rahaeifard ◽  
M. T. Ahmadian
Keyword(s):  
Genetic Algorithm ◽  
Contact Stiffness ◽  
Sample Surface ◽  
Geometric Parameters ◽  
Design Parameters ◽  
Normal Contact ◽  
Genetic Algorithm Method ◽  
Normal Contact Stiffness ◽  
Afm Cantilever ◽  
Micro Cantilever

Atomic force microscopes (AFM) are widely used for feature detection and scanning surface topography of different materials. Contrast of topography images is significantly influenced by the sensitivity of AFM micro cantilever which means enhancement of sensitivity leads to increase of topography images resolution So, in the last years numerous scientists interested in studying the effects of different parameters such as geometric one on the sensitivity of AFM micro cantilevers. V-shape micro cantilever types of AFMs probe are widely used to scan various types of surfaces. In V-shape micro cantilevers, there are many geometric and design parameters which influence the flexural sensitivity of the micro beam, noticeably. In this paper evaluation of optimum geometric parameters and optimum cantilever slope is considered as a significant purpose in order to obtain maximum flexural sensitivity by using genetic algorithm optimization method. In the calculations, the normal and lateral interaction forces between AFM tip and sample surface is considered and modeled by linear springs which represent the contact stiffness of the sample surface. Also, a relation for flexural sensitivity of AFM cantilever as a function of geometric parameters and cantilever slope is derived which is used in optimization step by employing a genetic algorithm program. Using genetic algorithm method, the optimum geometric parameters and cantilever slope are calculated which maximize the flexural sensitivity of the first mode of a V-shape cantilever for various values of normal contact stiffness. These optimum parameters versus normal contact stiffness are presented in some result figures. The results show that for any contact stiffness, there are a cantilever slope and a set of geometrical parameters which provide the maximum sensitivity for AFM probe. Adopting these parameters for the design of V-shape micro cantilever according to the sample contact stiffness, maximum flexural sensitivity can be obtained, so that high contrast images are reachable.

Nonlinear vibration of rectangular atomic force microscope cantilevers by considering the Hertzian contact theory

2010 ◽  
Vol 88 (5) ◽  
pp. 333-348 ◽  
Author(s):  
Ali Sadeghi ◽  
Hassan Zohoor
Keyword(s):  
Atomic Force Microscope ◽  
Timoshenko Beam ◽  
Frequency Ratio ◽  
Contact Stiffness ◽  
Sample Surface ◽  
Hertzian Contact ◽  
Nonlinear Frequency ◽  
Lateral Contact ◽  
Atomic Force ◽  
Contact Position

The nonlinear flexural vibration for a rectangular atomic force microscope cantilever is investigated by using Timoshenko beam theory. In this paper, the normal and tangential tip–sample interaction forces are found from a Hertzian contact model and the effects of the contact position, normal and lateral contact stiffness, tip height, thickness of the beam, and the angle between the cantilever and the sample surface on the nonlinear frequency to linear frequency ratio are studied. The differential quadrature method is employed to solve the nonlinear differential equations of motion. The results show that softening behavior is seen for most cases and by increasing the normal contact stiffness, the frequency ratio increases for the first mode, but for the second mode, the situation is reversed. The nonlinear-frequency to linear-frequency ratio increases by increasing the Timoshenko beam parameter, but decreases by increasing the contact position for constant amplitude for the first and second modes. For the first mode, the frequency ratio decreases by increasing both of the lateral contact stiffness and the tip height, but increases by increasing the angle α between the cantilever and sample surface.

A fresh insight into the non-linear vibration of double-tapered atomic force microscope cantilevers by considering the Hertzian contact theory

2010 ◽  
Vol 225 (1) ◽  
pp. 233-247 ◽  
Author(s):  
A Sadeghi ◽  
H Zohoor
Keyword(s):  
Atomic Force Microscope ◽  
Timoshenko Beam ◽  
Frequency Ratio ◽  
Contact Stiffness ◽  
Sample Surface ◽  
Hertzian Contact ◽  
Linear Frequency ◽  
Atomic Force ◽  
Non Linear ◽  
Contact Position

The non-linear flexural vibration for a double-tapered atomic force microscope cantilever has been investigated by using the Timoshenko beam theory. In this article, the normal and tangential tip—sample interaction forces are found from the Hertzian contact model, and the effects of the contact position, normal and lateral contact stiffness, height of the tip, thickness of the beam, angle between the cantilever and the sample surface, and breadth and height taper ratios on the non-linear frequency to linear frequency ratio have been studied. The differential quadrature method is employed to solve the non-linear differential equations of motion. The results show that the softening behaviour is seen for all cases. The non-linear frequency to linear frequency ratio increases by increasing the Timoshenko beam parameter and breadth and height taper ratios, but decreases by increasing the contact position for the first and second modes. For the first vibrational mode, the non-linear frequency to linear frequency ratio increases by increasing the height of the tip and the angle α between the cantilever and sample surface. By increasing the normal contact stiffness, the frequency ratio increases for the first mode.

scholarly journals Измерения контактной жесткости в атомно-силовом микроскопе

2020 ◽  
Vol 90 (11) ◽  
pp. 1951
Author(s):  
А.В. Анкудинов ◽  
М.М. Халисов
Keyword(s):  
Atomic Force Microscope ◽  
Analytical Model ◽  
Contact Interaction ◽  
Relative Position ◽  
Mechanical Characteristics ◽  
Contact Stiffness ◽  
Sample Surface ◽  
Atomic Force ◽  
Imaging Mode ◽  
Cantilever Probe

A method is proposed for increasing the accuracy of nanomechanical measurements in an atomic force microscope. To describe the contact interaction of the cantilever with the sample, an analytical model was used that takes into account the following factors: the cantilever probe sticks to the sample surface or slides along it, the geometric and mechanical characteristics of the sample and cantilever, and their relative position. Under the assumption of sliding, a filter was developed to correct the signals of contact stiffness and deformation measured on a sample with a developed relief. The use of the filter is illustrated in images obtained in an atomic force microscope with an imaging mode based on point-by-point registration of the force quasistatic interaction of the cantilever probe with the sample.

Lorentz Contact Resonance Imaging for Atomic Force Microscopes: Probing Mechanical and Thermal Properties on the Nanoscale

2013 ◽  
Vol 21 (6) ◽  
pp. 18-24 ◽  
Author(s):  
Eoghan Dillon ◽  
Kevin Kjoller ◽  
Craig Prater
Keyword(s):  
Viscoelastic Properties ◽  
Contact Stiffness ◽  
Mechanical And Thermal Properties ◽  
Resonance Modes ◽  
Atomic Force ◽  
Resonance Frequencies ◽  
Other Information ◽  
Afm Cantilever ◽  
Stiffness And Damping ◽  
Contact Resonance

Atomic force microscopy (AFM) has been widely used in both industry and academia for imaging the surface topography of a material with nanoscale resolution. However, often little other information is obtained. Contact resonance AFM (CR-AFM) is a technique that can provide information about the viscoelastic properties of a material in contact with an AFM probe by measuring the contact stiffness between the probe and sample. In CR-AFM, an AFM cantilever is oscillated, and the amplitude and frequency of the resonance modes of the cantilever are monitored. When a probe or sample is oscillated, the tip sample interaction can be approximated as an ideal spring-dashpot system using the Voigt-Kelvin model shown in Figure 1. Contact resonance frequencies of the AFM cantilever will shift depending on the contact stiffness, k, between the tip and sample. The damping effect on the system comes from dissipative tip sample forces such as viscosity and adhesion. Damping, η, is observed in a CR-AFM system by monitoring the amplitude and Q factor of the resonant modes of the cantilever. This contact stiffness and damping information can then be used to obtain information about the viscoelastic properties of the material when fit to an applicable model.

Characterization of Multi-Phase and Multi-Component Polymer Systems Using the Atomic Force Microscope

1999 ◽  
Vol 5 (S2) ◽  
pp. 962-963
Author(s):  
M. VanLandingham ◽  
X. Gu ◽  
D. Raghavan ◽  
T. Nguyen
Keyword(s):  
Energy Dissipation ◽  
Atomic Force Microscope ◽  
Mechanical Response ◽  
Sample Surface ◽  
Phase Changes ◽  
Phase Imaging ◽  
Polymer Systems ◽  
Atomic Force ◽  
Phase Images ◽  
Multi Phase

Recent advances have been made on two fronts regarding the capability of the atomic force microscope (AFM) to characterize the mechanical response of polymers. Phase imaging with the AFM has emerged as a powerful technique, providing contrast enhancement of topographic features in some cases and, in other cases, revealing heterogeneities in the polymer microstructure that are not apparent from the topographic image. The enhanced contrast provided by phase images often allows for identification of different material constituents. However, while the phase changes of the oscillating probe are associated with energy dissipation between the probe tip and the sample surface, the relationship between this energy dissipation and the sample properties is not well understood.As the popularity of phase imaging has grown, the capability of the AFM to measure nanoscale indentation response of polymers has also been explored. Both techniques are ideal for the evaluation of multi-phase and multi-component polymer systems.

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