Universality in Oscillating Flows

Ekinci, K. L.; Karabacak, Devrez M.; Yakhot, Victor

doi:10.1103/physrevlett.101.264501

Cited by 38 publications

(51 citation statements)

References 19 publications

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“…Therefore, we believe that it is of a great importance to improve the Q-factors in aqueous environment for bio-sensing applications such as in situ, real-time detection. Recent progress towards understanding Qfactor degradation due to surrounding fluidic environments has occurred due to work by Ekinci et al [185,186], who studied doubly clamped silicon beam resonators in a gaseous nitrogen environment. They found that fluidic dissipation appears to saturate at high frequencies that are related to the relaxation times of the fluid; this finding enabled them to quantitatively state how the NEMS geometry can be utilized to minimize fluidic dissipation.…”

Section: Perspectives and Challengesmentioning

confidence: 99%

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

et al. 2011

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Recent advances in nanotechnology have led to the development of nano-electro-mechanical systems (NEMS) such as nanomechanical resonators, which have recently received significant attention from the scientific community. This has not only been for their capability for the label-free detection of bio/chemical-molecules at single-molecule (or atomic) resolution for future applications such as the early diagnostics of diseases such as cancer, but also for their unprecedented ability to detect physical quantities such as molecular weight, elastic stiffness, surface stress, and surface elastic stiffness for adsorbed molecules on the surface. Most experimental works on resonator-based molecular detection have been based on the principle that molecular adsorption onto a resonator surface increases the effective mass, and consequently decreases the resonant frequencies of the nanomechanical resonator. However, this principle is insufficient to provide fundamental insights into resonator-based molecular detection at the nanoscale; this is due to recently proposed novel nanoscale detection principles including various effects such as surface effects, nonlinear oscillations, coupled resonance, and stiffness effects. Furthermore, these effects have only recently been incorporated into existing physical models for resonators, and therefore the universal physical principles governing nanoresonator-based detection have not been completely described. Therefore, our objective in this review is to overview the current attempts to understand the underlying mechanisms in nanoresonator-based detection using physical models coupled to computational simulations and/or experiments. Specifically, we will focus on issues of special relevance to the dynamic behavior of nanoresonators and their applications in biological/chemical detection: the resonance behavior of micro/nano-resonators; resonator-based chemical/biological detection; physical models of various nanoresonators such as nanowires, carbon nanotubes, and graphene. We pay particular attention to experimental and computational approaches that have been useful in elucidating the mechanisms underlying the dynamic behavior of resonators across multiple and disparate spatial/length scales, and the resulting insight into resonator-based detection that has been obtained. We additionally provide extensive discussion regarding potentially fruitful future research directions coupling experiments and simulations in order to develop a fundamental understanding of the basic physical principles that govern NEMS and NEMS-based sensing and detection applications.

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Section: Perspectives and Challengesmentioning

confidence: 99%

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

et al. 2011

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“…For bulk fluids, by contrast, direct mechanical observation of non-Newtonian behavior has been limited to solid structures interacting with dilute gases [14]. In this case, the effects can be predicted rigorously by the Boltzmann equation [15].…”

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confidence: 99%

Viscoelastic Flows in Simple Liquids Generated by Vibrating Nanostructures

et al. 2013

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Newtonian fluid mechanics, in which the shear stress is proportional to the strain rate, is synonymous with the flow of simple liquids such as water. We report the measurement and theoretical verification of non-Newtonian, viscoelastic flow phenomena produced by the high-frequency (20 GHz) vibration of gold nanoparticles immersed in water-glycerol mixtures. The observed viscoelasticity is not due to molecular confinement, but is a bulk continuum effect arising from the short time scale of vibration. This represents the first direct mechanical measurement of the intrinsic viscoelastic properties of simple bulk liquids, and opens a new paradigm for understanding extremely high frequency fluid mechanics, nanoscale sensing technologies, and biophysical processes. DOI: 10.1103/PhysRevLett.111.244502 PACS numbers: 47.50.Àd, 47.61.Àk, 62.25.Fg, 87.15.ht A fluid is said to be Newtonian if it exhibits a simple linear relationship between shear stress and strain rate. This description, which underlies conventional fluid dynamics, provides an excellent approximation to the behavior of real fluids, provided the time scale for measurement is long compared to the time required for stresses to propagate in the fluid. In simple liquids, including water and glycerol, these ''relaxation times'' are on the order of 1 ps-1 ns [1][2][3]. These time scales are short compared to the time scales associated with the motion of macroscopic objects in the fluids, which allows interactions between solid structures and simple fluids to be described by classical Navier-Stokes treatments [4,5]. These treatments hold even for micrometer-scale objects, such as the cantilevers found in atomic force microscopes and microelectromechanical devices, because they have characteristic vibrational frequencies in the kHz to MHz range [6,7]. Non-Newtonian fluid mechanics is therefore conventionally associated only with complex fluids that have long relaxation times, such as polymer solutions and melts, dense colloidal suspensions such as corn starch in water, and fluids near their phase transitions [8,9]. Scaling objects down to nanometer size scales increases their characteristic vibrational frequencies up to the GHz or THz range [10]. Fluid-structure interactions on these length scales thus have the potential to show significant deviations from Newtonian behavior, even for simple liquids.Departures from Newtonian behavior have been reported for simple liquids under extreme confinement, due to structural reorganization and surface effects on the molecular scale [11][12][13]. For bulk fluids, by contrast, direct mechanical observation of non-Newtonian behavior has been limited to solid structures interacting with dilute gases [14]. In this case, the effects can be predicted rigorously by the Boltzmann equation [15]. For simple bulk liquids, however, rigorous theoretical description of, and experimental access to, the non-Newtonian regime remain outstanding problems in the physical sciences.We access this regime directly for the first time by exciting a...

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“…16 For an oscillating flow, a measure of the importance of molecular scale dynamics is given by the Weissenberg number Wi ¼ xs where x is the frequency of oscillation of the nanobeam and s is the fluid relaxation time scale. 22 For atmospheric air s % k=c % 0:2 ns where k is the mean free path of a fluid molecule between collisions and c is the speed of sound. For the resonator considered here, in atmospheric air, this yields Wi % 0:01 ( 1 which indicates that the flow field can be treated as a continuum.…”

Section: Resultsmentioning

confidence: 99%

“…For the resonator considered here, in atmospheric air, this yields Wi % 0:01 ( 1 which indicates that the flow field can be treated as a continuum. 22 Although we have not explored this aspect further, we emphasize that it would be possible to use our general approach with a latticeBoltzmann solver 23,24 for the fluid-solid interactions to quantify the dynamics in the Wi տ 1 limit if desired.…”

Section: Resultsmentioning

confidence: 99%

The stochastic dynamics of a nanobeam near an optomechanical resonator in a viscous fluid

Epstein

Paul

2013

Journal of Applied Physics

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Frequency response of cantilever beams immersed in viscous fluids near a solid surface with applications to the atomic force microscope J. Appl. Phys. 98, 114913 (2005) We quantify the Brownian driven, stochastic dynamics of an elastic nanobeam immersed in a viscous fluid that is partially wrapped around a microdisk optical resonator. This configuration has been proposed as an optomechanical and nanoscale analog of the atomic force microscope [Srinivasan et al., Nano Lett. 11, 791 (2011)]. A small gap between the nanobeam and microdisk is necessary for the optomechanical transduction of the mechanical motion of the nanobeam. We compute the stochastic dynamics of the nanobeam in fluid for the precise conditions of the laboratory using deterministic finite element simulations and the fluctuation dissipation theorem. We investigate the dynamics of a nanobeam in water and in air and quantify the significance of the fluid-solid interaction between the nanobeam and the optical resonator. Our results in air show that, despite the complex geometry of the nanobeam, it can still be represented approximately as a damped simple harmonic oscillator. On the other hand, when the nanobeam is immersed in water there are significant deviations from the dynamics of a simple harmonic oscillator. The small gap between the nanobeam and the microdisk is found to be a significant source of additional dissipation. In air, the quality factor of the mechanical oscillation of the nanobeam is reduced by an order of magnitude due to the presence of the microdisk, however, the dynamics remain underdamped even in the presence of the microdisk. On the other hand, when placed in water, the dynamics without the microdisk is underdamped and with the microdisk the dynamics become strongly over damped. V C 2013 AIP Publishing LLC.[http://dx

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Universality in Oscillating Flows

Cited by 38 publications

References 19 publications

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

Viscoelastic Flows in Simple Liquids Generated by Vibrating Nanostructures

The stochastic dynamics of a nanobeam near an optomechanical resonator in a viscous fluid

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