Determination of complex shear modulus with thickness shear mode resonators

Lücklum, Ralf; Behling, C.; Cernosek, R.W.; Martin, Stephen J.

doi:10.1088/0022-3727/30/3/006

Cited by 178 publications

(133 citation statements)

References 16 publications

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“…This outcome is in qualitative agreement with the expected stiffening of the polymer network at high frequencies (Lucklum et al, 1997). The value of G AFM of the less swollen gel at 8 vol% cleaner concentration is peculiar for TSR 1 , because it is smaller than the corresponding value of the highly swollen gel at 1 vol%.…”

Section: Resultssupporting

confidence: 87%

Paradigm change in hydrogel sensor manufacturing: from recipe-driven to specification-driven process optimization

Windisch¹,

Eichhorn²,

Lienig³

et al. 2016

J. Sens. Sens. Syst.

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Abstract. The volume production of industrial hydrogel sensors lacks a quality-assuring manufacturing technique for thin polymer films with reproducible properties. Overcoming this problem requires a paradigm change from the current recipe-driven manufacturing process to a specification-driven one. This requires techniques to measure quality-determining hydrogel film properties as well as tools and methods for the control and optimization of the manufacturing process. In this paper we present an approach that comprehensively addresses these issues. The influence of process parameters on the hydrogel film properties and the resulting sensor characteristics have been assessed by means of batch manufacturing tests and the application of several measurement techniques. Based on these investigations, we present novel methods and a tool for the optimization of the cross-linking process step, with the latter being crucial for the sensor sensitivity. Our approach is applicable to various sensor designs with different hydrogels. It has been successfully tested with a sensor solution for surface technology based on PVA/PAA hydrogel as sensing layer and a piezoelectric thickness shear resonator as transducer. Finally, unresolved issues regarding the measurement of hydrogel film parameters are outlined for future research.

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Section: Resultssupporting

confidence: 87%

Paradigm change in hydrogel sensor manufacturing: from recipe-driven to specification-driven process optimization

Windisch¹,

Eichhorn²,

Lienig³

et al. 2016

J. Sens. Sens. Syst.

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“…The transmission line model is especially used when calculating multi-layered structures, giving adequate results and reducing the amount of computation power and time to realize the simulations. It has been previously used to calculate the transmission spectrum of phononic crystals with good results [9][10][11][12][13][14].…”

Section: (B)mentioning

confidence: 99%

“…The transmission and reflection coefficients are calculated using an overall effective acoustic impedance of the PnC, Z L . It is important to notice that the effective acoustic impedance is frequency dependent and is different from the characteristic impedance of the material, Z c , which is equal to the density, q, multiplied by the speed of sound of the material, c. The concept considers the reflection and transmission of waves in layer interfaces and also inside each layer [9,13]. The effective acoustic impedance of layer i can be calculated using Eq.…”

Section: (B)mentioning

confidence: 99%

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

et al. 2017

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. Fullydisposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity. Measurement: Journal of the International Measurement Confederation, 102, pp. 20-25. doi: 10.1016Confederation, 102, pp. 20-25. doi: 10. /j.measurement.2017 This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent b s t r a c tPhononic crystals are artificial structures with unique capabilities to control the transmission of acoustic waves. These novel periodic composite structures bring new possibilities for developing a fundamentally new sensor principle that combines features of both ultrasonic and resonant sensors. This paper reports the design, fabrication and evaluation of a phononic crystal sensor for biomedical applications, especially for its implementation in point of care testing technologies. The key feature of the sensor system is a fully-disposable multi-layered phononic crystal liquid sensor element with symmetry reduction and a resonant cavity. The phononic crystal structure consists of eleven layers with high acoustic impedance mismatch. A defect mode was utilized in order to generate a well-defined transmission peak inside the bandgap that can be used as a measure. The design of the structures has been optimized with simulations using a transmission line model. Experimental realizations were performed to evaluate the frequency response of the designed sensor using different liquid analytes. The frequency of the characteristic transmission peaks showed to be dependent on the properties of the analytes used in the experiments. Multi-layered phononic crystal sensors can be used in applications, like point of care testing, where the on-line measurement of small liquid samples is required.

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“…A general approach is to consider the acoustic impedance, Z L , at the interface between the acoustic device and the coating. This surface acoustic impedance summarizes the overall acoustic load acting on the acoustic device and can be applied to single and multilayer arrangements 10 . With some approximations, this model can be translated into equivalent circuit models used in electrical engineering [11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

Influence of viscoelasticity and interfacial slip on acoustic wave sensors

McHale

Lücklum

Newton

et al. 2000

Journal of Applied Physics

100

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Acoustic wave devices with shear horizontal displacements, such as quartz crystal microbalances (QCM) and shear horizontally polarised surface acoustic wave (SH-SAW) devices provide sensitive probes of changes at solid-solid and solid-liquid interfaces.Increasingly the surfaces of acoustic wave devices are being chemically or physically modified to alter surface adhesion or coated with one or more layers to amplify their response to any change of mass or material properties. In this work, we describe a model that provides a unified view of the modification in the shear motion in acoustic wave systems by multiple finite thickness loadings of viscoelastic fluids. This model encompasses QCM and other classes of acoustic wave devices based on a shear motion of the substrate surface and is also valid whether the coating film has a liquid or solid character. As a specific example, the transition of a coating from liquid to solid is modelled using a single relaxation time Maxwell model. The correspondence between parameters from this physical model and parameters from alternative acoustic impedance models is given explicitly. The characteristic changes in QCM frequency and attenuation as a function of thickness are illustrated for a single layer device as the coating is varied from liquid-like to that of an amorphous solid. Results for a double layer structure are given explicitly and the extension of the physical model to multiple layers is described. An advantage of this physical approach to modelling the response of acoustic wave devices to multilayer films is that it provides a basis for considering how interfacial slip boundary conditions might be incorporated into the acoustic impedance used within circuit models of acoustic wave devices. Explicit results are derived for interfacial slip occurring at the substrate-layer 1 interface using a single real slip parameter, s, which has inverse dimensions of impedance. In terms of acoustic impedance, such interfacial slip acts as a single-loop negative feedback. It is suggested that these results can also be viewed as arising from a double-layer model with an infinitesimally thin slip layer which gives rise to a modified acoustic load of the second layer. Finally, the difficulties with defining appropriate slip boundary conditions between any two successive layers in a multilayer device are outlined from a physical point of view.

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Determination of complex shear modulus with thickness shear mode resonators

Cited by 178 publications

References 16 publications

Paradigm change in hydrogel sensor manufacturing: from recipe-driven to specification-driven process optimization

Paradigm change in hydrogel sensor manufacturing: from recipe-driven to specification-driven process optimization

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

Influence of viscoelasticity and interfacial slip on acoustic wave sensors

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