scholarly journals Generalized Hertz model for bimodal nanomechanical mapping

2016 ◽  
Vol 7 ◽  
pp. 970-982 ◽  
Author(s):  
Aleksander Labuda ◽  
Marta Kocuń ◽  
Waiman Meinhold ◽  
Deron Walters ◽  
Roger Proksch
Keyword(s):  
Contact Mechanics ◽  
Small Amplitude ◽  
Sample Surface ◽  
Hertzian Contact ◽  
Modes Of Operation ◽  
Hertz Model ◽  
Force Microscopy ◽  
Atomic Force ◽  
Resonant Modes ◽  
Shape And Size

Bimodal atomic force microscopy uses a cantilever that is simultaneously driven at two of its eigenmodes (resonant modes). Parameters associated with both resonances can be measured and used to extract quantitative nanomechanical information about the sample surface. Driving the first eigenmode at a large amplitude and a higher eigenmode at a small amplitude simultaneously provides four independent observables that are sensitive to the tip–sample nanomechanical interaction parameters. To demonstrate this, a generalized theoretical framework for extracting nanomechanical sample properties from bimodal experiments is presented based on Hertzian contact mechanics. Three modes of operation for measuring cantilever parameters are considered: amplitude, phase, and frequency modulation. The experimental equivalence of all three modes is demonstrated on measurements of the second eigenmode parameters. The contact mechanics theory is then extended to power-law tip shape geometries, which is applied to analyze the experimental data and extract a shape and size of the tip interacting with a polystyrene surface.

Shape and size of epididymal sperm from Gir bulls using atomic force microscopy: A nanoscale characterization of epididymal sperm

2020 ◽  
Vol 20 (1) ◽  
pp. 37-41
Author(s):  
Andrielle Thainar Mendes Cunha ◽  
Luciano Paulino Silva ◽  
José Oliveira Carvalho ◽  
Margot Alves Nunes Dode
Keyword(s):  
Atomic Force Microscopy ◽  
Epididymal Sperm ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nanoscale Characterization ◽  
Shape And Size

scholarly journals Nanoscale Differences in the Shape and Size of X and Y Chromosome-Bearing Bovine Sperm Heads Assessed by Atomic Force Microscopy

PLoS ONE ◽  
2013 ◽  
Vol 8 (3) ◽  
pp. e59387 ◽  
Author(s):  
José O. Carvalho ◽  
Luciano P. Silva ◽  
Roberto Sartori ◽  
Margot A. N. Dode
Keyword(s):  
Atomic Force Microscopy ◽  
Y Chromosome ◽  
Force Microscopy ◽  
Bovine Sperm ◽  
Atomic Force ◽  
Shape And Size

Nonlinear Vibrations in Contact Atomic Force Microscopy

2003 ◽  
Author(s):  
Joseph A. Turner
Keyword(s):  
Nonlinear Vibration ◽  
Multiple Scales ◽  
Contact Stiffness ◽  
Vibration Response ◽  
Hertzian Contact ◽  
Force Microscopy ◽  
Softening Behavior ◽  
Atomic Force ◽  
Frequency Relation ◽  
Frequency Curves

The nonlinear vibration response of an atomic force microscope cantilever in contact with a vibrating sample is investigated. The tip-sample contact is modeled using Hertzian contact mechanics. The method of multiple scales is used to analyze this problem in which it is assumed that the beam remains in contact with the moving surface at all times. The primary result from this analysis is the amplitude-frequency relation for the various flexural modes. The amplitude-frequency curves exhibit softening behavior as expected. The amount of softening is shown to depend on the linear contact stiffness as well as the specific mode. The modal sensitivity to nonlinearity is the result of the nonlinearity being restricted to a single position. The mode shape greatly affects the degree to which the nonlinearity influences the frequency response. The Hertzian restriction is then loosened slightly such that variations in nonlinear contact stiffness are examined. These results depend on the linear contact stiffness and mode number as well. The nonlinear vibration response is expected to provide new insight on the nonlinear tip mechanics present in these systems.

scholarly journals Using atomic force microscopy to work with the cell surface of Candida albicans

2021 ◽  
Vol 2091 (1) ◽  
pp. 012026
Author(s):  
E M Filippova ◽  
U V Nesvizhski ◽  
S A Titov ◽  
A I Glukhov
Keyword(s):  
Atomic Force Microscopy ◽  
Candida Albicans ◽  
Cell Walls ◽  
Opportunistic Infections ◽  
Modes Of Operation ◽  
Force Microscopy ◽  
Operating Modes ◽  
Biological Objects ◽  
Atomic Force ◽  
Mucous Membranes

Abstract Candida albicans is a yeast-like fungus that lives on human mucous membranes and skin and does not cause infections. However, it plays a role in the development of opportunistic infections in immunocompromised people. In this work, we would like to evaluate the possibility of studying the cell wall of C. albicans by atomic force microscopy, as well as compare the operating modes of the microscope and choose optimal one for working with the fungus. Atomic force microscopy is a powerful tool for evaluating surfaces, including the cell walls of biological objects. The microscope is capable of operating in different modes, but in this study we compared two of them: contact and semi-contact. These methods are the most popular for evaluating the surfaces of biological objects. Comparison of the modes was carried out on the C. albicans strain. The surface of the strain was scanned by atomic force microscopy, and the curves of the dependence of the sensor deviation from the distance to the object were recorded. Scanning and recording of curves were carried out in two modes of operation of the microscope: contact and semi-contact, as well as three sensors: soft, medium and hard.

Small-Amplitude Atomic Force Microscopy

2005 ◽  
Vol 7 (8) ◽  
pp. 707-712 ◽  
Author(s):  
S. V. Patil ◽  
P. M. Hoffmann
Keyword(s):  
Atomic Force Microscopy ◽  
Small Amplitude ◽  
Force Microscopy ◽  
Atomic Force

Sufficient condition for reliability measurement of sample geometry by atomic force microscopy

2020 ◽  
pp. 11-15
Author(s):  
Alexander S. Kravchuk ◽  
Anzhelika I. Kravchuk
Keyword(s):  
Atomic Force Microscopy ◽  
Preliminary Investigation ◽  
Sample Surface ◽  
Sufficient Condition ◽  
Surface Geometry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Geometric Deviations ◽  
Reliability Measurement ◽  
Microscope Stage

A sufficient condition for determining the reliability of geometry measurements using atomic force microscopy for relatively small cantilever tilt angles is proposed. A relationship between the basic geometric parameters of surface roughness, geometric deviations of the probe, the angles of the cantilever and the inclination of the side faces of the probe, as well as the dimensions of the nonlocal point of the probable contact of its side faces with protrusions of roughness has been established. As a sufficient condition for the reliability of geometry measurements using atomic force microscopy, an obvious requirement is accepted. It determines the smallness of the ratio of the sizes of a nonlocal point to the distance between neighboring nonlocal points. Publications in which the measurement of surface nano-geometry of the samples does not indicate the roughness of the sample surface and the probe, the angles at the tip of the probe and the tilt of the cantilever, as well as the best resolution (smallest step) at which the study is carried out, cannot be accepted as reliable, because the results obtained in them are probabilistic in nature. The surface images obtained using atomic force microscopy without proper justification for the resolution (value of the measurement step) represent only a qualitative picture, on the basis of which it makes no sense to carry out any computational manipulations. In order to increase the reliability of measurements of surface geometry using atomic force microscopy, it is necessary to radically increase the accuracy of the manufacture of probes, as well as use probes with the smallest possible angle at the apex. In addition, it is necessary to make changes in the design of the atomic force microscopy. In particular, the automatic rotation of the microscope stage should be designed. It should provide closeness the probe axis direction to the normal to the average plane of the sample. This “integral” angle of rotation of the microscope stage is easily iteratively determined at the stage of preliminary investigation of the geometry of the surface of the sample. In this case, it will be necessary to geometrically increase the length of the cantilever so that the base extends beyond the limits of the sample.

Features of the Manufacturing Process of Silicon Tips for Cantilevers

2021 ◽  
Vol 26 (3-4) ◽  
pp. 234-245
Author(s):  
A.V. Novak ◽  
◽  
V.R. Novak ◽  
A.V. Rumyantsev ◽  
◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Silicon Film ◽  
Statistical Parameter ◽  
Sample Surface ◽  
Test Sample ◽  
Oxygen Atmosphere ◽  
Maximum Height ◽  
Force Microscopy ◽  
Atomic Force ◽  
Crystallographic Planes

Sample surface examination in atomic force microscopy is carried out using cantilevers having the form of elastic consoles with sharp needle (tip) at the free end. Quality of images obtained from atomic force microscope (AFM) heavily depends on tip sharpness degree. Silicon cantilevers made based on wet anisotropic etching are widely used in atomic force microscopy. This paper studies the dependence of the shape and size of the resulting tip on the concentration of KOH in the solution, as well as the effect of pyrogenic oxidation and oxidation in a dry oxygen atmosphere on the sharpness of the tip during the sharpening process. It was shown that when 70 % concentration is used, tips with the highest aspect ratio and maximum height are obtained. In this case, the shape of the needle is an octagonal pyramid, the lateral faces of which are formed by eight crystallographic planes from {311} and {131}. It was found that in a two-stage sharpening process, consisting of pyrogenic oxidation and oxidation in a dry oxygen atmosphere, it is possible to form sufficiently sharp probes with a tip radius of 2–5 nm and an apex angle of 14–24°. It has been established that a one-stage sharpening process based on pyrogenic oxidation provides only the production of probes with a radius of about 14 nm. Comparative tests of the manufactured probes in obtaining AFM images of a test sample of a polycrystalline silicon film with hemispherical grains (HSG-Si) were presented. Research study has revealed that such a statistical parameter as the relative increment of the surface area Sdr is the most sensitive to probe sharpness for surfaces of the HSG-Si film type.

Investigation of Epitaxial GaN Films by Conductive Atomic Force Microscopy

2003 ◽  
Vol 764 ◽  
Author(s):  
S. Dogan ◽  
J. Spradlin ◽  
J. Xie ◽  
A. A. Pomarico ◽  
R. Cingolani ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Surface ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Topological Features ◽  
Atomic Force ◽  
Local Current ◽  
Semiconductor Junction ◽  
Surrounding Areas ◽  
Conduction Properties

AbstractThe current conduction in GaN is very topical and is the topic of a vast amount of research. By simultaneously mapping the topography and the current distribution, conductive atomic force microscopy (C-AFM) has the potential to establish a correlation between topological features and localized current paths. In this study, this technique was applied to image the conduction properties of as-grown and post-growth chemically etched samples GaN epitaxial layers on a microscopic scale. Our results show that prismatic planes have a significantly higher conductivity than the surrounding areas of the sample surface. A large and stable local current was mainly observed from the walls of the etched pits, under forward and reverse bias of the metallized AFM tip/semiconductor junction.

The Atomic-Scale Hysteresis in Non Contact Atomic Force Microscopy

2010 ◽  
Author(s):  
Hossein Nejat Pishkenari ◽  
Ali Meghdari
Keyword(s):  
Contact Region ◽  
Sample Surface ◽  
System Size ◽  
Interaction Force ◽  
Atomic Scale ◽  
Force Microscopy ◽  
Atomic Force ◽  
Environment Temperature ◽  
Plane Direction ◽  
Dynamics Simulations

In this research, the hysteresis in the tip-sample interaction force in noncontact force microscopy (NC-AFM) is measured with the aid of atomistic dynamics simulations. The observed hystersis in the interaction force and displacement of the system atoms leads to the loss of energy during imaging of the sample surface. Using molecular dynamics simulations it is shown that the mechanism of the energy dissipation occurs due to bistabilities caused by atomic jumps of the surface and tip atoms in the contact region. The conducted simulations demonstrate that when a gold coated nano probe is brought close to the Au (001) surface, the tip apex atom jumps to the surface; and instantaneously, four surface atoms jump away from the surface toward the tip apex atom. Along this line, particular attention is dedicated to the dependency of the energy loss to different parameters such as the environment temperature, the tip orientation, the surface plane direction, the system size, the distance of the closest approach and the tip oscillation frequency.

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