Fluid loading of a Lamb-wave sensor

White, Richard M.; Wenzel, S.W.

doi:10.1063/1.99047

Cited by 92 publications

(46 citation statements)

References 4 publications

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“…FPW devices (see Figure 2-1) are plate wave devices with plates that are only a few percent of an acoustic wavelength thick (typically 2-3 fim thick) [63][64][65][66][67][68][69][70]. The plate is a composite structure consisting of a silicon nitride layer, an aluminum ground plane, and a sputtered zinc oxide piezoelectric layer, all supported by a silicon substrate.…”

Section: Flexural Plate Wave (Fpw) Devicesmentioning

confidence: 99%

“…(The surface-parallel motion is parallel to the wave propagation direction) Typical device resonant frequencies are 2-7 MHz. FPW devices have been used in a great variety of applications, including vapor sensing, observation of polymer glass transitions, liquid properties such as density and viscosity, and biosensing [63,64,67,[70][71][72][73][74][75][76]. In addition, these devices have interesting capabilities for pumping fluids and moving solids [77,78].…”

Section: Flexural Plate Wave (Fpw) Devicesmentioning

confidence: 99%

“…The shift in resonance frequency on liquid loading of the TSM surface can be related to the square root of the product of the density and viscosity of the liquid, although precise agreement with such models is not always observed experimentally [10,11]. SH-APM, FPW, and STW devices also exhibit frequency shifts on liquid loading that are related to the liquid density and viscosity [54,57,65,70,73].…”

Section: Effects In Liquidsmentioning

confidence: 99%

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Acoustic Wave Sensors

1996

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Section: Flexural Plate Wave (Fpw) Devicesmentioning

confidence: 99%

Section: Flexural Plate Wave (Fpw) Devicesmentioning

confidence: 99%

Section: Effects In Liquidsmentioning

confidence: 99%

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Acoustic Wave Sensors

1996

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“…[25,28,20,36,21,42,671 In liquids, however, the mass sensitivity and frequency resolution of resonant sensors is degraded by the low quality factor and large effective mass that is induced by viscous drag. While certain designs have the potential to greatly alleviate these limitations, [75,19,391 their sensitivity is still inferior to air or vacuum based resonators [73]. To overcome this problem, various groups have employed the 'dip and dry' method, by which the resonance frequency is measured in air before and after the device has been exposed to the sample.…”

Section: List Of Figuresmentioning

confidence: 99%

Suspended microchannel resonators for biomolecular detection

Burg

Manalis

2003

Applied Physics Letters

213

139

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Microfabricated transducers enable the label-free detection of biological molecules in nanoliter sized samples. Integrating microfluidic detect ion and sample-preparat ion can greatly leverage experimental efforts in systems biology and pharmaceutical research by increasing analysis throughput while dramatically reducing reagent cost.Microfabricated resonant mass sensors are among the most sensitive devices for chemical detection, but degradation of the sensitivity in liquid has so far hindered their successful application in biology. This thesis introduces a type of resonant transducer that overcomes this limitation by a new device design: Adsorption of molecules to the inside walls of a suspended microfluidic channel is detected by measuring the change in mechanical resonance frequency of the channel. In contrast to resonant mass sensors submersed in water, the sensitivity and frequency resolution of the suspended microchannel resonator is not degraded by the presence of the fluid. Our device differs from a vibrating tube densitometer in that the channel is very thin, and only molecules that bind to the walls can build up enough mass to be detected; this provides a path to specificity via molecular recognition by immobilized receptors.Suspended silicon nitride channels have been fabricated through a sacrificial polysilicon process and bulk micromachining, and the packaging and microfluidic interfacing of the resonant sensors has been addressed. Device characterization at 30 mTorr ambient pressure reveals a quality factor of more than 10,000 for water filled resonators; this is two orders of magnitude higher than previously demonstrated Q-values of resonant mass sensors for biological measurements.Calculation of the noise and the sensitivity of suspended microchannel resonators indi-

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“…The first is to use a flexural plate wave which, although it has an out-of-plane component of displacement, has a wave speed less than the speed of sound in the liquid. 2,3 Under these circumstances, the wave can no longer generate compressional waves in the liquid and so does not suffer a large attenuation. The second approach is to use an acoustic wave mode that has surface parallel displacements.…”

Section: Introductionmentioning

confidence: 99%

Theoretical mass sensitivity of Love wave and layer guided acoustic plate mode sensors

McHale

Newton

Martin

2002

Journal of Applied Physics

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A model for the mass sensitivity of Love wave and layer guided shear horizontal acoustic plate mode ͑SH-APM͒ sensors is developed by considering the propagation of shear horizontally polarized acoustic waves in a three layer system. A dispersion equation is derived for this three layer system and this is shown to contain the dispersion equation for the two layer system of the substrate and the guiding layer plus a term involving the third layer, which is regarded as a perturbing mass layer. This equation is valid for an arbitrary thickness perturbing mass layer. The perturbation, ⌬ , of the wave speed for the two-layer system by a thin third layer of density, p and thickness ⌬h is shown to be equal to the mass per unit area multiplied by a function dependent only on the properties of the substrate and the guiding layer, and the operating frequency of the sensor. The independence of the function from the properties of the third layer means that the mass sensitivity of the bare, two-layer, sensor operated about any thickness of the guiding layer can be deduced from the slope of the numerically or experimentally determined dispersion curve. Formulas are also derived for a Love wave on an infinite thickness substrate describing the change in mass sensitivity due to a change in frequency. The consequences of the various formulas for mass sensing applications are illustrated using numerical calculations with parameters describing a ͑rigid͒ poly͑methylmethacrylate͒ wave-guiding layer on a finite thickness quartz substrate. These calculations demonstrate that a layer-guided SH-APM can have a mass sensitivity comparable to, or higher, than that of Love waves propagating on the same substrate. The increase in mass sensitivity of the layer guided SH-APMs over previously studied SH-APM sensors is of significance, particularly for liquid sensing applications. The relevance of the dispersion curve to experiments using higher frequencies or frequency hopping and to experiments using thick guiding layers is discussed.

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Fluid loading of a Lamb-wave sensor

Cited by 92 publications

References 4 publications

Acoustic Wave Sensors

Acoustic Wave Sensors

Suspended microchannel resonators for biomolecular detection

Theoretical mass sensitivity of Love wave and layer guided acoustic plate mode sensors

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