Shear horizontal waves sensors for analysis of physical parameters of liquids and their mixtures (original) (raw)
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Applications of Acoustic Wave Devices for Sensing in Liquid Environments
Applied Spectroscopy Reviews, 2006
Acoustic wave devices such as thickness shear mode (TSM) resonators and shear horizontal surface acoustic wave (SH-SAW) devices can be utilized for characterizing physical properties of liquids and for chemical sensor applications. Basic device configurations are reviewed and the relationships between experimental observables (frequency shifts and attenuation) and physical properties of liquids are presented. Examples of physical property (density and viscosity) determination and also of chemical sensing are presented for a variety of liquid phase applications. Applications of TSMs and polymer-coated guided SH-SAWs for chemical sensing and uncoated SH-SAWs for "electronic tongue" applications are also discussed.
Guided Acoustic wave sensors for liquid environments
Journal of Physics D: Applied Physics
Surface acoustic wave (SAW) based sensors for applications to gaseous environments have been widely investigated since the last 1970s. More recently, the SAW-based sensors focus has shifted towards liquid-phase sensing applications: the SAW sensor contacts directly the solution to be tested and can be utilized for characterizing physical and chemical properties of liquids, as well as for biochemical sensor applications. The design of liquid phase sensors requires the selection of several parameters, such as the acoustic wave polarizations (i.e., elliptical, longitudinal and shear horizontal), the wave-guiding medium composition (i.e., homogeneous or non-homogeneous half-spaces, finite thickness plates or composite suspended membranes), the substrate material type and its crystallographic orientation. The paper provides an overview of different types of SAW sensors suitable for application to liquid environments, and intents to direct the attention of the designers to combinations of materials, waves nature and electrode structures that affect the sensor performances.
Acoustic wave–liquid interactions
Materials Science and Engineering: C, 2000
. Ž . Surface acoustic waves SAWs are one of a broad class of acoustic wave AW techniques that have been applied to the study of Ž . physical changes at the solid-liquid interface. Other examples include shear horizontally polarised SAWs SH-SAWs , acoustic plate Ž . modes, Love waves and quartz crystal microbalances QCMs . Several factors motivate and favour these techniques. The sensing surface is highly mass sensitive, it is accessible and can be chemically modified, and it provides a rapid in situ method for studying dynamic chemical and biochemical changes. Moreover, for a Newtonian fluid, the AW only entrains fluid within a penetration depth of the interface, so that the technique truly probes interfacial changes. However, many studies of liquids using these acoustic techniques have been limited to fixed pools of liquid in contact with a device surface. In this work, a damped harmonic oscillator model is described, providing a unified view of the mass damping of the shear motion in SAW, SH-SAW, and QCM AW systems by finite thickness loadings of viscoelastic fluids. The simplicity of the model also allows the effect of fluid slip at the solid-liquid interface to be examined. In the limit of small relaxation time and thick fluid coating, the model recovers the expected limit with acoustic devices acting as sensors of the device area coated by the fluid. In the large relaxation time limit, the fluid acts as an amorphous solid and the influence of the acoustic shearing motion is able to extend to the free surface of the fluid, thus inducing shear wave resonances. To complement the theory, an Ž . experiment is described which uses pulses of high frequency 169 MHz Rayleigh SAWs to probe a small stripe of a viscous fluid Ž w x w x . polydimethylsiloxane PDMS oil with a viscosity between 10 000 and 100 000 centistokes cSt as it dynamically evolves in shape. The cross-sectional profile of the liquid is a well-defined spherical cap shape and this is recorded using a video based interferometry arrangement. This allows a range of geometrical parameters to be obtained and correlated with the acoustic signals. The changing geometry of the stripe does not simply decrease the magnitude of the SAW transmission as the fluid wets a progressively larger area of the surface, but also specific significant attenuations are observed. Interpreting these attenuations within the damped harmonic oscillator model, data from a range of experiments can all be fitted by relaxation rates obtained from the viscosity and a high frequency shear Ž .
Interfacial properties and the response of the thickness-shear-mode acoustic wave sensor in liquids
Langmuir, 1993
The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in various liquids has been characterized by the network analysis method. Models for this system based only on bulk liquid parameters fail to explain the behavior of the device with respect to series resonant frequency. Use of sensors with controlled surface free energy of the metal electrodes has been employed to demonstrate the importance of the liquid-solid interface in determining the response of the device. The contribution of the effects of surface roughness on the sensor response is discussed. Additionally, a previously-published four-layer model is successful in predicting the trends in values for the series resonant frequency for a set of mixed water-methanol solutions.
AIP Advances, 2023
Surface acoustic wave (SAW) devices have been used in biochemical assays due to their high sensitivity. The device sensitivity is a function of changes in the density and viscosity of the liquid. Here, we studied the effect of fluid viscosity using a 250 MHz quartz shear-horizontal (SH)-SAW biosensor by monitoring different concentrations of binary aqueous/glycerol solutions. In this study, the sensitivity of the biosensor was determined by fitting the data to models derived from perturbation theory. Measurements in water were used as the reference. For a 0% to 50% glycerol solution, an 87 ○-204 ○ separation in the phase shift was observed. The slope of the plot of the phase shift vs (ηρ) 0.5 was used to indicate the sensor's sensitivity. The sensitivity for our 250 MHz quartz SH-SAW sensors was calculated to be 3.7 × 10 −3 m 2 s Kg. The corresponding mass sensitivity was determined to be 9.25 × 10 5 m 2 Kg. The limit of detection was calculated to be 36 picograms (pg), while the limit of quantification or LOQ was calculated to be 109 pg. Traditionally, liquid phase measurements have been challenging for SAW devices because liquids dampen the vibrating sensors severely. This problem has been largely solved using a transverse (shear) wave instead of the more popular longitudinal or Rayleigh waves. Liquid measurements are now possible using transverse waves, also known as shear waves, because transverse waves are only minimally attenuated by liquids. Shear-horizontal SAW sensors (SH-SAW) show great promise as labelfree biosensors because of their ability to handle liquid samples. However, the viscosity of the liquid still induces loading effects and can be measured when the liquid is loaded onto the SH-SAW propagating surface (delay line). When the liquid above the delay line is perturbed by physical or chemical changes, such as binding to a receptor, it alters the propagating acoustic wave. The SH-SAW device can measure these changes in liquid properties as a change in the wave's phase compared to the original wave. The device's phase shift was recorded as a function of the changes in the density and viscosity of the binary glycerol solution and used to determine the sensitivity in the linear dynamic range of responses.
Biosensors and Bioelectronics, 2004
In this work, we describe a novel pulse mode shear horizontal-surface acoustic wave (SH-SAW) polymer coated biosensor that monitors rapid changes in both amplitude and phase. The SH-SAW sensors were fabricated on 36 • rotated Y-cut X propagating lithium tantalate (36 YX.LT). The sensitivity of the device to both mass loading and visco-elastic effects may be increased by using a thin guiding layer of cross-linked polymer. Two acoustic modes are excited by the electrodes in this crystalline direction. Metallisation of the propagation path of the 36 YX.LT devices allows the two modes to be discriminated. Successive polymer coatings resulted in the observation of resonant conditions in both modes as the layer thickness was increased. Using the 36 YX.LT devices, we have investigated the application of a novel pulse mode system by sensing a sequence of deposition and removal of a biological layer consisting of vesicles of the phospholipid POPC. A continuous wave system was used to verify the accuracy of the pulse mode system by sensing a series of poly(ethylene glycol) (PEG) solutions. The data clearly demonstrates the ability of the 36 YX.LT pulse mode system to provide rapid measurements of both amplitude and phase for biosensing applications.
Analytical Chemistry, 2001
The design and performance of guided shear horizontal surface acoustic wave (guided SH-SAW) devices on LiTaO 3 substrates are investigated for high-sensitivity chemical and biochemical sensors in liquids. Despite their structural similarity to Rayleigh SAW, SH-SAWs often propagate slightly deeper within the substrate, hence preventing the implementation of high-sensitivity detectors. The device sensitivity to mass and viscoelastic loading is increased using a thin guiding layer on the device surface. Because of their relatively low shear wave velocity, various polymers including poly(methyl methacrylate) (PMMA) and cyanoethyl cellulose (cured or cross-linked) are investigated as the guiding layers to trap the acoustic energy near the sensing surface. The devices have been tested in biosensing and chemical sensing experiments. Suitable design principles for these applications are discussed with regard to wave guidance, electrical passivation of the interdigital transducers from the liquid environments, acoustic loss, and sensor signal distortion. In biosensing experiments, using near-optimal PMMA thickness of ∼2 µm, mass sensitivity greater than 1500 Hz/(ng/mm 2) is demonstrated, resulting in a minimum detection limit less than 20 pg/mm 2. For chemical sensor experiments, it is found that optimal waveguide thickness must be modified to account for the chemically sensitive layer which also acts to guide the SH-SAW. A detection limit of 780 (3 × peak-to-peak noise) or 180 ppb (3 × rms noise) is estimated from the present measurements for some organic compounds in water.
An acoustic transmission sensor for the longitudinal viscosity of fluids
Sensors and Actuators A: Physical, 2013
Physical fluid parameters like viscosity, mass density and sound velocity can be determined utilizing ultrasonic sensors. We introduce the concept of a recently devised transmission based sensor utilizing pressure waves to determine the longitudinal viscosity, bulk viscosity, and second coefficient of viscosity of a sample fluid in a test chamber. A model is presented which allows determining these parameters from measurement values by means of a fit. The setup is particularly suited for liquids featuring higher viscosities for which measurement data are scarcely available to date. The setup can also be used to estimate the sound velocity in a simple manner from the phase of the transfer function.
Analytical Chemistry, 2005
Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36°rotated Y-cut LiTaO 3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work.
High frequency longitudinal and shear acoustic waves in glass-forming liquids
Journal of Physics: Conference Series, 2010
Nano-scale effects on Young's modulus of nanoimprint polymers measured by photoacoustic metrology T Kehoe, J Bryner, V Reboud et al. Towards full-field photothermoelastic microscopy using a CCD camera J Charnay, D Teyssieux and B Cretin Thermal diffusivity measurement by photothermal radiometry under random excitation and parametric analysis S Brahim, J L Bodnar et and P Grossel Paraffin oil thermal diffusivity determination using a photothermal deflection setup with a 2.3m pump: a first step towards methane detection A Hamdi, N Yacoubi, F Genty et al. High frequency longitudinal and shear acoustic waves in glass-forming liquids View the table of contents for this issue, or go to the journal homepage for more