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A comparative study of Love-type wave vibrations in a distinct piezoelectric (PE) material thin film with a highly and weakly dielectric interface with an elastic pre-stressed elastic plate is investigated analytically. Using the PZT-2, PZT-4, PZT-5H, LiNbO3 and BaTiO3 numerical data for the PE material, we achieved significant outcomes of PE and flexoelectric effect in the study. Dispersion equations are achieved analytically for both electrically open and short cases together with highly and weekly conducting interfaces in the transcendental complex form. Outcomes specify that microstructures having flexoelectricity has a significant influence on dispersion features. The existence of flexoelectricity shows that complex phase velocity with a positive imaginary part increases the phase velocity of considered waves with time. Numerical results are highlighted graphically and validated with existing results. The present study is a prior attempt to show the flexoelectricity influence with weekly and highly conducting interfaces and also to show that the outcomes are significant to obtain better surface acoustic wave device's performance. [ABSTRACT FROM AUTHOR]

Research describing a theoretical investigation of acoustic waves propagating in potassium niobate plates is presented. In particular the influence of a conducting electrode and conducting layer is examined as perturbation theory cannot be used in this instance.

In this paper, we present an approach to studying the mode coupling vibrations in two-port thin-film bulk acoustic wave resonator (FBAR) devices with two pairs of electrodes deposited on the zinc oxide film. The two-dimensional plate theory established in our previous work is employed, which takes into account the coupling of the operating thickness-extensional mode with the extensional, flexural, fundamental and second-order thickness-shear modes. The propagation of straight-crested waves in the plate is studied, and the state-vector approach is successfully used to simplify the derivation process. For a structurally symmetric device, the modes are separated into quasi symmetric and antisymmetric ones. Frequency spectra and corresponding mode shapes are obtained under the stress-free boundary conditions, respectively, and then coupling effects and energy trapping phenomenon are discussed in detail. Some results for structures with asymmetric electrode distributions are also shown. It is found that the choice of aspect ratio has a great effect on mode couplings of FBAR devices. This study will be useful for the design of FBAR filters and sensors. [ABSTRACT FROM AUTHOR]

A piezoelectric plate supporting the propagation of antisymmetric zero-order (A0) Lamb wave is proposed to be used as a hydroacoustical waveguide emitter that transmits a bulk acoustic wave into a liquid. The emitter's directional pattern has been theoretically and experimentally examined for a frequency band of 89-107 kHz. An angular acoustic beam scanning was revealed to be realized by varying the A0 wave frequency. It is shown that, unlike complicated emitting systems of phased array type, this nonmechanical scanning could be realized in a simple device. The obtained results are in a good agreement with the theoretical ones. [ABSTRACT FROM AUTHOR]

The main problem in development of the acoustoelectronic gas sensors is the search of the elements which are sensitive to the presence of different gases. In this paper we suggest to use for this purpose the piezoelectric quartz resonators with the mycelium films of mushroom Lentinula edodes strain F-249, which was cultivated in synthetic medium. The extract of mycelium was deposited on the surface of the resonator. The measurements of the frequency dependencies of the real and imaginary parts of electrical impedance of the resonator allowed finding the density, elastic constants and viscosity of the films under study. The influence of various gases (ammonia, formaldehyde, ethylacetate) and volatile liquids (acetone, acetic acid, chloroform) on physical properties of the extracts of mushroom Lentinula edodes mycelium has been investigated. It has been found that it is possible to use the mycelium films of mushroom Lentinula edodes prepared by different ways as sensitive film to ammonia, formaldehyde and ethyl acetate. [ABSTRACT FROM AUTHOR]

Capabilities of the acoustic wave sensing without using special sorbent films are studied at normal conditions with the use of three types of biological objects to detect coliphages, bacteria and yeasts in ordinary liquid rich growth Luria-Bertani media as well as for these biological objects immobilized in agarose hydrogel in various concentrations (and in highly diluted Luria-Bertani broth as reference media also). The method does not require special bath and large volume of test samples (∼100 μL), demonstrates high long-term stability, but possesses some inherent limitations to be discussed. Dilution of the analytes in the reference media is detected to change electric conductivity, but not viscosity of the suspension. The values of the conductivity σ are around 0.5 S/m. The minimum detectable bacteria concentration is estimated as 100 - 1000 cell/ml. [ABSTRACT FROM AUTHOR]