Equivalent-circuit model of the squeezed gas film in a silicon accelerometer

Veijola, Timo; Kuisma, Heikki; Lahdenpera, J.; Ryhänen, Tapani

doi:10.1016/0924-4247(95)00995-7

Cited by 419 publications

(305 citation statements)

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“…Note that a multiplicative constant of 0.9 was used in all three to improve the fits. Viscous effects [15,16] and squeeze-film effects [17,18], commonly observed in MEMS, did not introduce significant damping for the small high-frequency devices up to atmospheric pressure.…”

mentioning

confidence: 93%

High-Frequency Nanofluidics: An Experimental Study Using Nanomechanical Resonators

2007

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Here we apply nanomechanical resonators to the study of oscillatory fluid dynamics. A highresonance-frequency nanomechanical resonator generates a rapidly oscillating flow in a surrounding gaseous environment; the nature of the flow is studied through the flow-resonator interaction. Over the broad frequency and pressure range explored, we observe signs of a transition from Newtonian to non-Newtonian flow at ωτ ≈ 1, where τ is a properly defined fluid relaxation time. The obtained experimental data appears to be in close quantitative agreement with a theory that predicts purely elastic fluid response as ωτ → ∞.

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confidence: 93%

High-Frequency Nanofluidics: An Experimental Study Using Nanomechanical Resonators

2007

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“…In step (c), these data are used in Eqs. 1,20,21,22,23,24,27,29 to calculate the various forces acting on the cantilever. The forces are combined in step (d) to calculate the resultant force and torque acting on the cantilever and hence find its effective stiffness.…”

Section: Jump-to Simulationsmentioning

confidence: 99%

“…Assuming the fluid to be air under ambient conditions, the effective air viscosity differs from the normal air viscosity because at small gaps the air becomes compressed and therefore the continuum approximation usually employed in squeeze flow becomes less applicable. To deal with the compression, the dynamic viscosity is modified to give: [24] (4) Here kg/m.s, which is the viscosity of air at standard temperature and pressure, and m, which is the mean free path length of air at standard temperature and pressure. The quantity is equal to the Knudsen number, , which is defined here as the ratio of the mean free path length to the gap between the moving object and the flat surface.…”

Section: Force Applied To Tip Due To Fluid Squeezingmentioning

confidence: 99%

A Dynamic Model of the Jump-To Phenomenon During AFM Analysis

Bowen

Cheneler

2012

Langmuir

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The measurement of the physical properties of surfaces on the nanoscale is a long-standing problem, and the atomic force microscope (AFM) has enabled the investigation of surface energies and mechanical properties over a range of length scales. The ability to measure these properties for softer materials presents a challenge when interpreting data obtained from such measurements, in particular because of the dynamics of the compliant AFM microcantilever. This work attempts to better understand the interaction between an AFM tip and samples of varying elastic modulus, in the presence of attractive van der Waals forces. A theoretical model is presented in which the dynamics of the approach of an atomic force microscope cantilever tip towards a surface, prior to and during the van der Waals-induced jump-to phenomenon, are included. The cantilever mechanics incorporates the motion of the air through which the cantilever moves, the acceleration, inertia and torque of the cantilever, and the squeezing of the fluid between the cantilever tip and the surface, leading to elastohydrodynamic lubrication and deformation of the substrate. Simulations of the cantilever approach are compared to measurements performed using an atomic force microscope, and the effect of cantilever drive velocity is investigated. Cantilevers presenting (i) spherical colloid probe tips and (ii) pyramidal tips are employed, and substrates exhibiting Young's moduli of 3 MPa, 500 MPa, and 75 GPa are measured. The analysis presented could be extended to enhance understanding of dynamic phenomena in micro/nanoelectromechanical systems such as resonators and microrheometers, particularly those which contain soft materials and also where surface interactions are important.

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“…For sensors/actuators operating over a wide range, as in microswitch applications, this is often not the case and a model valid over the whole range must be found [5][6]. The same goes, for example, for squeeze-film damping for which models that remain valid for large displacements with respect to the gap [7] must be used. In this paper, a method for modelling the large-displacement actuation of deformable microstructures is proposed and illustrated, in the case of a circular axisymmetric plate.…”

Section: Introductionmentioning

confidence: 99%