Cantilever Dynamics With Attractive and Repulsive Tip Interactions

2009 ◽  
Author(s):  
Ishita Chakraborty ◽  
Balakumar Balachandran
Keyword(s):  
Period Doubling ◽  
Experimental System ◽  
Nonlinear Phenomena ◽  
Strong Nonlinearity ◽  
Force Microscopy ◽  
Compliant Surface ◽  
Atomic Force ◽  
Macro Scale ◽  
Repulsive Forces ◽  
Period Doubling Bifurcations

In tapping mode atomic force microscopy (AFM) operations, typically, a micro-scale cantilever undergoes long-range attractive and short-range repulsive forces as it approaches the surface. Due to the strong nonlinearity of the tip-sample interaction forces, a variety of nonlinear phenomena has been observed. In order to obtain a better understanding of such phenomena, in this work, a macro-scale experimental system is constructed with attractive and repulsive tip interactions. Magnetic forces are used to generate the attractive forces, and impact with a compliant surface is used to produce the repulsive forces. A reduced-order model for this system has been developed with Derjaguin-Muller-Toporov (DMT) contact mechanics. In prior work conducted in the group, period-doubling bifurcations have been observed close to near grazing conditions when AFM cantilevers are operated between first and second natural frequencies of the system. This phenomenon is further explored in this article.

OFF-RESONANCE CANTILEVER DYNAMICS IN THE PRESENCE OF ATTRACTIVE AND REPULSIVE TIP INTERACTION FORCES

2011 ◽  
Vol 11 (04) ◽  
pp. 603-620 ◽  
Author(s):  
ISHITA CHAKRABORTY ◽  
B. BALACHANDRAN
Keyword(s):  
Excitation Frequency ◽  
Nonlinear Phenomena ◽  
Nonlinear Phenomenon ◽  
Clock Frequency ◽  
Interaction Forces ◽  
Reduced Order ◽  
Compliant Surface ◽  
Cantilever Structure ◽  
Macro Scale ◽  
Repulsive Forces

In dynamic atomic force microscopy (AFM), as the tip of the base-excited micro-cantilever approaches the sample surface, this cantilever tip typically experiences long-range attractive and short-range repulsive forces. Due to the strongly nonlinear nature of these tip-sample interaction forces, various nonlinear phenomena including grazing contact-related phenomena have been observed. With the aim of obtaining a better understanding of such phenomena, a macro-scale experimental system has been constructed with attractive and repulsive tip interactions. In this arrangement, the macro-scale cantilever structure is harmonically excited at its base, a combination of magnets is used to generate the attractive forces, and impacts with a compliant surface are used to produce the repulsive forces. The separation between the tip and the compliant surface is used as a control parameter and the associated qualitative changes in the system dynamics are studied on Poincaré sections constructed by using the excitation frequency as the clock frequency. Off-resonance excitations are considered and a period- doubling window is observed for near-grazing impacts when the excitation frequency is in between the first and the second natural frequencies of the system. To explore the experimental observations further, a reduced-order model of the macro-scale system is developed with Derjaguin–Muller–Toporov (DMT) contact mechanics. The dynamics of the reduced-order system is found to agree well with the corresponding experimental observations. The nonlinear phenomenon observed during off-resonance excitations can form a basis for engineering grazing (zero-speed) impacts or low-speed impacts between a tapping mode AFM cantilever tip and the considered sample. In addition, the macro-scale experimental arrangement can serve as a vehicle to understand the dynamics of elastic structures subjected to different combinations of attractive and repulsive tip forces.

scholarly journals Chaotic dynamics of a pulse modulated control system for a heating unit

2018 ◽  
Vol 224 ◽  
pp. 02055
Author(s):  
Yuriy A. Gol’tsov ◽  
Alexander S. Kizhuk ◽  
Vasiliy G. Rubanov
Keyword(s):  
Control System ◽  
Differential Equations ◽  
Chaotic Dynamics ◽  
Period Doubling ◽  
Classical Period ◽  
Nonlinear Phenomena ◽  
Pulse Control ◽  
Heating Unit ◽  
Border Collision Bifurcation ◽  
Period Doubling Bifurcations

The dynamic modes and bifurcations in a pulse control system of a heating unit, the condition of which is described through differential equations with discontinuous right–hand sides, have been studied. It has been shown that the system under research can demonstrate a great variety of nonlinear phenomena and bifurcation transitions, such as quasiperiodicity, multistable behaviour, chaotization of oscillations through a classical period–doubling bifurcations cascade and border–collision bifurcation.

Material Property Characterization of Costal Cartilage Using AFM Indentation

2009 ◽  
Author(s):  
S. Tripathy ◽  
E. J. Berger
Keyword(s):  
Material Characterization ◽  
Costal Cartilage ◽  
Indentation Modulus ◽  
Hertz Contact ◽  
Force Microscopy ◽  
Afm Indentation ◽  
Atomic Force ◽  
Macro Scale ◽  
Property Characterization

Costal cartilage is one of the load bearing tissues of the rib cage. Literature on the material characterization of the costal cartilage is limited. Atomic force microscopy has been extremely successful in characterizing the elastic properties of articular cartilage, but no studies have been published on costal cartilage. In this study AFM indentations on human costal cartilage were performed and compared with macro scale indentation data. Spherical beaded tips of three sizes were used for the AFM indentations. The Hertz contact model for spherical indenter was used to analyze the data and obtain the Young’s modulus. The costal cartilage was found to be almost linearly elastic till 600 nm of indentation depth. It was also found that the modulus values decreased with the distance from the junction. The modulus values from macro indentations were found to be 2-fold larger than the AFM indentation modulus.

ELECTROSPINNING OF CONTINUOUS CARBON NAONOFIBER-FILLED COMPOSITE FIBERS

2012 ◽  
Vol 05 ◽  
pp. 545-550
Author(s):  
Seyed Hamed Aboutalebi ◽  
Zahra Gholamvand ◽  
Mansoor Keyanpour-Rad
Keyword(s):  
Carbon Nanofibers ◽  
Polymer Fibers ◽  
Composite Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Macro Scale ◽  
Electrospinning Method ◽  
Scale Structures ◽  
Filled Composite ◽  
Pan Fibers

In order to translate the superior properties of carbon nanofibers (CNFs) to macro-scale structures, an electrospinning route capable of placing CNFs into a continuous nano-scale composite fibril is introduced. In this work, composite fibers were produced by electrospinning solution of polyacrylonitrile ( PAN ) with carbon nanofibers dispersed in dimethylformamide ( DMF ), which is an effective solvent for carbon nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) demonstrated rough and globular surfaces on the CNF containing fibers. Raman spectra confirmed the presence of CNFs in the polymer fibers prepared employing the electrospinning method. Raman observation served as the direct evidence of successful filling of PAN fibers with CNFs and complemented the results obtained by SEM and AFM studies.

Application of Atomic Force Microscopy to the Study of Lubricant Additive Films

2005 ◽  
Vol 127 (2) ◽  
pp. 405-415 ◽  
Author(s):  
K. Topolovec Miklozˇicˇ ◽  
H. A. Spikes
Keyword(s):  
Atomic Force Microscopy ◽  
Lubricant Additive ◽  
Friction Modifier ◽  
Force Microscopy ◽  
Atomic Force ◽  
Film Forming ◽  
Macro Scale ◽  
Force Mode ◽  
Viscous Boundary ◽  
Boundary Films

Constant force mode atomic force microscopy is used to examine the films formed on steel surfaces by three different types of lubricant additive. Work on molybdenum dithiocarbamate friction modifier additive solutions shows that this additive forms tiny domains of low friction on the high spots of rubbed surfaces. Complementary Raman surface analysis suggests that these domains represent crystallites of MoS2. Study of the reaction films formed by zinc dialkyldithiophosphate additives confirms the formation of pad-like structures by these additives on rubbed surfaces. Primary and secondary forms of the additive are shown to form films of different morphology and properties. Colloid probe atomic force microscopy has also been applied to study the boundary film-forming properties of functionalized viscosity modifier polymers. It is shown that these polymers can form viscous boundary films on rubbed surfaces which produce much lower friction than the corresponding, nonfunctionalised polymers. Overall it is suggested that atomic force microscopy can provide valuable information concerning the nature and properties of boundary films formed by lubricant additives especially when used in parallel with macro-scale friction and film thickness measurements.

scholarly journals Self-Assembly of Rice Bran Globulin Fibrils in Electrostatic Screening: Nanostructure and Gels

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Lihua Huang ◽  
Yehui Zhang ◽  
Haibin Li
Keyword(s):  
Ionic Strength ◽  
Rice Bran ◽  
Self Assembly ◽  
Gel Properties ◽  
Sem Images ◽  
Force Microscopy ◽  
Atomic Force ◽  
Repulsive Forces ◽  
Low Ionic Strength ◽  
Kinetics Of

The effects of various ionic strengths and protein concentrations on the fibrils structure and gel properties of rice bran globulin (RBG) at pH 2.0 were investigated using atomic force microscopy (AFM), rheometer, and scanning electron microscope (SEM). AFM images showed the morphology of assembling RBG fibrils from strand beads to becoming branch clustered, when electrostatic repulsive forces attenuated gradually with increasing ionic strength. NaCl seems to accelerate the kinetics of fibrils formation, resulting in a significant increase in Th T fluorescence intensity. The increased ionic strengths promote particle size increasing and zeta potential decreasing synchronously. The percolation modelG'~C-Cpnbe used to calculate theoretical RBG gels concentration at various ionic strengths (0–500 mM), which decreased from 15.17 ± 0.63 to 2.26 ± 0.27 wt%. SEM images exhibited a granular mesh-like gel structure. A more homogenous structure occurred in low ionic strength. This study elucidates properties of RBG fibrils and gels as a bioactive material.

scholarly journals Nanoscale Material Heterogeneity of Glowworm Capture Threads Revealed by AFM

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3500
Author(s):  
Dakota Piorkowski ◽  
Bo-Ching He ◽  
Sean J. Blamires ◽  
I-Min Tso ◽  
Deborah M. Kane
Keyword(s):  
Vertical Orientation ◽  
Force Microscopy ◽  
Nano Scale ◽  
Fast Fourier Transform Analysis ◽  
Atomic Force ◽  
Practical Usefulness ◽  
Macro Scale ◽  
Phase Images ◽  
Supporting Material ◽  
Materials Used

Adhesive materials used by many arthropods for biological functions incorporate sticky substances and a supporting material that operate synergistically by exploiting substrate attachment and energy dissipation. While there has been much focus on the composition and properties of the sticky glues of these bio-composites, less attention has been given to the materials that support them. In particular, as these materials are primarily responsible for dissipation during adhesive pull-off, little is known of the structures that give rise to functionality, especially at the nano-scale. In this study we used tapping mode atomic force microscopy (TM-AFM) to analyze unstretched and stretched glowworm (Arachnocampa tasmaniensis) capture threads and revealed nano-scale features corresponding to variation in surface structure and elastic modulus near the surface of the silk. Phase images demonstrated a high resolution of viscoelastic variation and revealed mostly globular and elongated features in the material. Increased vertical orientation of 11–15 nm wide fibrillar features was observed in stretched threads. Fast Fourier transform analysis of phase images confirmed these results. Relative viscoelastic properties were also highly variable at inter- and intra-individual levels. Results of this study demonstrate the practical usefulness of TM-AFM, especially phase angle imaging, in investigating the nano-scale structures that give rise to macro-scale function of soft and highly heterogeneous materials of both natural and synthetic origins.

Interaction Forces Between Thermoresponsive Surface and Colloidal Particle in Aqueous Solution Studied Using Atomic Force Microscopy

2006 ◽  
Vol 942 ◽  
Author(s):  
Naoyuki Ishida ◽  
Mikio Kobayashi
Keyword(s):  
Aqueous Solution ◽  
Colloidal Particles ◽  
Interaction Force ◽  
Surface Hydrophobicity ◽  
Solution Temperature ◽  
Interaction Forces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydrophobic Particles ◽  
Repulsive Forces

ABSTRACTThe interaction forces between poly(N-isopropylacrylamide) (PNIPAAm)-grafted surfaces and colloidal particles in an aqueous solution were investigated using an atomic force microscope (AFM). Measurements were conducted between a smooth silicon wafer on which PNIPAAm was terminally grafted and silica particles hydrophobized with a silanating reagent in an aqueous electrolyte solution under controlled temperature. Below the lower critical solution temperature (LCST) of PNIPAAm, there were large repulsive forces between the surfaces, while attractive forces were observed above LCST. When surface hydrophobicity of the particles increased, the magnitude of attractive force tended to increase. The changes of hydration state of the grafted PNIPAAm chains depending on temperature is considered to greatly alter the interaction force properties. The role of the intermolecular interaction between the PNIPAAm chains and the hydrophobic particles in the interaction forces is discussed.

scholarly journals Surface Forces between Nanomagnetite and Silica in Aqueous Ca2+ Solutions Studied with AFM Colloidal Probe Method

2020 ◽  
Vol 4 (3) ◽  
pp. 41
Author(s):  
Illia Dobryden ◽  
Elizaveta Mensi ◽  
Allan Holmgren ◽  
Nils Almqvist
Keyword(s):  
Iron Ore ◽  
Adhesion Force ◽  
Surface Forces ◽  
Adhesion Forces ◽  
Interaction Forces ◽  
Colloidal Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Repulsive Forces ◽  
Qualitative Changes

Dispersion and aggregation of nanomagnetite (Fe3O4) and silica (SiO2) particles are of high importance in various applications, such as biomedicine, nanoelectronics, drug delivery, flotation, and pelletization of iron ore. In directly probing nanomagnetite–silica interaction, atomic force microscopy (AFM) using the colloidal probe technique has proven to be a suitable tool. In this work, the interaction between nanomagnetite and silica particles was measured with AFM in aqueous Ca2+ solution at different pH levels. This study showed that the qualitative changes of the interaction forces with pH and Ca2+ concentrations were consistent with the results from zeta-potential measurements. The repulsion between nanomagnetite and silica was observed at alkaline pH and 1 mM Ca2+ concentration, but no repulsive forces were observed at 3 mM Ca2+ concentration. The interaction forces on approach were due to van der Waals and electrical double-layer forces. The good fitting of experimental data to the DLVO model and simulations supported this conclusion. However, contributions from non-DLVO forces should also be considered. It was shown that an increase of Ca2+ concentration from 1 to 3.3 mM led to a less pronounced decrease of adhesion force with increasing pH. A comparison of measured and calculated adhesion forces with a few contact mechanics models demonstrated an important impact of nanomagnetite layer nanoroughness.

ON THE DYNAMICS OF A SIMPLE RATIONAL PLANAR MAP

2013 ◽  
Vol 23 (06) ◽  
pp. 1330021
Author(s):  
CHRISTOFOROS SOMARAKIS ◽  
JOHN S. BARAS
Keyword(s):  
Algebraic Structure ◽  
Period Doubling ◽  
Strange Attractors ◽  
Nonlinear Phenomena ◽  
Bifurcation Diagrams ◽  
Planar Map ◽  
Period Doubling Bifurcations

The dynamics of the map [Formula: see text] are discussed for various values of its parameters. Despite the simple algebraic structure, this map, recently introduced in the literature, is very rich in nonlinear phenomena. Multiple strange attractors, transitions to chaos via period-doubling bifurcations, quasiperiodicity as well as intermittency, interior crisis, hyperchaos are only a few. In this work, strange attractors, bifurcation diagrams, periodic windows, invariant characteristics are investigated both analytically and numerically.

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