Nonlinear Dynamics and Chaos of Microcantilever-Based TM-AFMs with Squeeze Film Damping Effects

Zhang, Wenming; Meng, Guang; Zhou, Jianbin; Chen, Jieyu

doi:10.3390/s90503854

Cited by 39 publications

(28 citation statements)

References 28 publications

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“…For example, the tip of an atomic force microscope (AFM) experiences harmonic variations in probe-surface separation distance from sub-micron down to the nanometer scale. During its oscillatory motion, the surrounding thin layer of gas induces a damping force on the tip, which is comparable with the AFM force output(Zhang et al 2009). The first step in proper modeling of flows in such small scales is the recognition of the rarefaction andnonequilibrium effects described by the local Kn.…”

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confidence: 79%

Molecular Dynamics Studies on Nanoscale Gas Transport

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2015

Encyclopedia of Microfluidics and Nanofluidics

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Three-dimensional molecular dynamics (MD) simulations of nanoscale gas flows are studied to reveal surface effects. A smart wall model that drastically reduces the memory requirements of MD simulations for gas flows is introduced. The smart wall molecular dynamics (SWMD) represents three-dimensional FCC walls using only 74 wall molecules. This structure is kept in the memory and utilized for each gas molecule surface collision. Using SWMD, fluid behavior within nano-scale confinements is studied for argon in dilute gas, dense gas, and liquid states. Equilibrium MD method is employed to resolve the density and stress variations within the static fluid. Normal stress calculations are based on the Irving-Kirkwood method, which divides the stress tensor into its kinetic and virial parts. The kinetic component recovers pressure based on the ideal gas law. The particle-particle virial increases with increased density, while the surface-particle virial develops due to the surface force field effects. Normal stresses within nano-scale confinements show anisotropy induced primarily by the surface forcefield and local variations in the fluid density near the surfaces. For dilute and dense gas cases, surface-force field that extends typically lnm from each wall induces anisotropic normal stress. For liquid case, this effect is further amplified by the density fluctuations that extend beyond the force field penetration region. Outside the wall force-field penetration and density fluctuation regions the normal stress becomes isotropic and recovers the thermodynamic pressure, provided that sufficiently large force cut-off distances are utilized in the computations. Next, non-equilibrium SWMD is utilized to investigate the surface-gas interaction effects on nanoscale shear-driven gas flows in the transition and free molecular flow regimes. For the specified surface properties and gassurface pair interactions, density and stress profiles exhibit a universal behavior inside the wall force penetration region at different flow conditions. Shear stress results are utilized to calculate the tangential momentum accommodation coefficient (TMAC) between argon gas and FCC walls. The TMAC value is shown to be independent of the flow properties and Knudsen number in ail simulations. Velocity profiles show distinct deviations from the kinetic theory based solutions inside the wall force penetration depth, while they match the linearized Boltzmann equation solution outside these zones.Afterwards, surface effects are studied as a function of the surface-gas potential strength ratio (£w//eff) for the shear driven argon gas flows in the early transition and free molecular flow regimes. Results show that increased results in increased gas density, leading towards monolayer adsorption on surfaces. The near wall velocity profile shows reduced gas slip, and eventually velocity stick with increased e^eff. Similarly, using MD predicted shear stress values and kinetic theory, TMAC are calculated as a function of ewf/sff, and TMAC values are shown to b...

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mentioning

confidence: 79%

Molecular Dynamics Studies on Nanoscale Gas Transport

Beşkök

Barışık

2015

Encyclopedia of Microfluidics and Nanofluidics

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“…For example, the tip of an atomic force microscope (AFM) experiences harmonic variations in probe-surface separation distance from sub-micron down to the nanometer scale. During its oscillatory motion, the surrounding thin layer of gas induces a damping force on the tip, which is comparable with the AFM force output (Zhang et al 2009). The first step in proper modeling of flows in such small scales is the recognition of the rarefaction and nonequilibrium effects described by the local Kn.…”

Section: Chapter 5 Surface-gas Interaction Effects On Nanoscale Gas Fmentioning

confidence: 99%

Molecular Dynamics Studies on Nanoscale Gas Transport

Beşkök

Barışık

2014

Encyclopedia of Microfluidics and Nanofluidics

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Three-dimensional molecular dynamics (MD) simulations of nanoscale gas flows are studied to reveal surface effects. A smart wall model that drastically reduces the memory requirements of MD simulations for gas flows is introduced. The smart wall molecular dynamics (SWMD) represents three-dimensional FCC walls using only 74 wall molecules. This structure is kept in the memory and utilized for each gas molecule surface collision. Using SWMD, fluid behavior within nano-scale confinements is studied for argon in dilute gas, dense gas, and liquid states. Equilibrium MD method is employed to resolve the density and stress variations within the static fluid. Normal stress calculations are based on the Irving-Kirkwood method, which divides the stress tensor into its kinetic and virial parts. The kinetic component recovers pressure based on the ideal gas law. The particle-particle virial increases with increased density, while the surface-particle virial develops due to the surface force field effects. Normal stresses within nano-scale confinements show anisotropy induced primarily by the surface forcefield and local variations in the fluid density near the surfaces. For dilute and dense gas cases, surface-force field that extends typically lnm from each wall induces anisotropic normal stress. For liquid case, this effect is further amplified by the density fluctuations that extend beyond the force field penetration region. Outside the wall force-field penetration and density fluctuation regions the normal stress becomes isotropic and recovers the thermodynamic pressure, provided that sufficiently large force cutoff distances are utilized in the computations. Next, non-equilibrium SWMD is utilized to investigate the surface-gas interaction effects on nanoscale shear-driven gas flows in the transition and free molecular flow regimes. For the specified surface properties and gassurface pair interactions, density and stress profiles exhibit a universal behavior inside the NOMENCLATURE English Symbols a Acceleration, nm/ns 2 Cm Mean thermal speed, nm/ns fu Force acting on molecule i from molecule j, N F Force, N H Channel height, nm k Modified Knudsen number, (No Units) h Boltzmann constant, (J K" 1) Kn Knudsen number, (No Units) L Channel length, nm m Mass, kg M Mach number, (No Units) N Number of molecules, # P Momentum P Pressure, kPa Q Mass parameter, (No Units) r ij Spacing between the molecules i and j, nm r c CutofF distance, nm R Specific gas constant, J K" 1 kg" 1 Re Reynolds number, (No Units) s Steps, (No Units

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“…Oftmals wird hierbei eine kugelförmige vorderste Spitze angesetzt. Es gibt zudem Simulationsberechnungen zum Wechselwirkungsverhalten für oszillierende Cantilever für den Ansatz mit kugelförmiger Spitze auf ebener Probe [8][9][10] und für allgemeinere Überlegungen [11; 14]. Vergleiche zwischen AFM-Messungen im Oszillationsmodus mit theoretischen Berechnungen gibt es zumeist nur für Annäherungen auf ebenen Proben.…”

Section: Ermittlung Des Antastpunktesunclassified

Kraftmikroskopie durch Einzelpunktantastung an Strukturkanten

Hüser¹,

Häßler-Grohne

Katzer

et al. 2010

Tm - Technisches Messen

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Zusammenfassung Im Zuge der immer höheren Integrationsdichte in der Halbleiterindustrie steigt der Bedarf, Strukturen mit Auflösungen im Sub-Nanometerbereich messen zu können. Grundlage für unterschiedliche optische und elektronenmikroskopische Verfahren zur Strukturbreitenmessung ist die Quantifizierung von Geometrieparametern an Kantenübergängen durch sondenmikroskopische Abtastung der Oberfläche. Dieser Artikel beschreibt ein Verfahren, Strukturkanten mittels Einzelpunktantastung mit Kraftmikroskopen abzutasten. Wesen dieser Strategie ist, die Sonde aus zur lokalen Oberflächenneigung passender Richtung antasten zu lassen. Dies liefert die Möglichkeit, Steigung und Verrundung der Kante sowie den Kantenfuß zu ermitteln.

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Nonlinear Dynamics and Chaos of Microcantilever-Based TM-AFMs with Squeeze Film Damping Effects

Cited by 39 publications

References 28 publications

Molecular Dynamics Studies on Nanoscale Gas Transport

Molecular Dynamics Studies on Nanoscale Gas Transport

Molecular Dynamics Studies on Nanoscale Gas Transport

Kraftmikroskopie durch Einzelpunktantastung an Strukturkanten

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