Amorphous SiC/c-ZnO-Based Quasi-Lamb Mode Sensor for Liquid Environments

Abstract

The propagation of the quasi-Lamb modes along a-SiC/ZnO thin composite plates was modeled and analysed with the aim to design a sensor able to detect the changes in parameters of a liquid environment, such as added mass and viscosity changes. The modes propagation was modeled by numerically solving the system of coupled electro-mechanical field equations in three media. The mode shape, the power flow, the phase velocity, and the electroacoustic coupling efficiency (K2) of the modes were calculated, specifically addressing the design of enhanced-coupling, microwave frequency sensors for applications in probing the solid/liquid interface. Three modes were identified that have predominant longitudinal polarization, high phase velocity, and quite good K2: the fundamental quasi symmetric mode (qS0) and two higher order quasi-longitudinal modes (qL1 and qL2) with a dominantly longitudinal displacement component in one plate side. The velocity and attenuation of these modes were calculated for different liquid viscosities and added mass, and the gravimetric and viscosity sensitivities of both the phase velocity and attenuation were theoretically calculated. The present study highlights the feasibility of the a-SiC/ZnO acoustic waveguides for the development of high-frequency, integrated-circuit compatible electroacoustic devices suitable for working in a liquid environment.

Experimental verification of a quasi-trapped degenerate mode magnetic acoustic resonator

“…Lamb waves in plates (FPM) have been shown to be operable within a liquid [23]. At the same frequency, the out of plane amplitude of the FPM based mass sensor will be at worst of the same order as the device reported in this work.…”

Theoretical Study of Quasi-Longitudinal Lamb Modes in SiN/c-AlN Thin Composite Plates for Liquid Sensing Applications

“…Generally, one way to obtain a thin AlN suspended membrane consist in the AlN layer deposition onto a silicon wafer covered with a thin SiN or SiO2 layer; the latter film acts as a stop etching layer during the silicon micromachining process. Thus the final suspended membrane is a bilayered membrane (SiN/AlN) that has no symmetry with respect to the mid-plane of the plate: the Lamb modes dispersion curves for this composite plate are expected to be different from those shown in Figure 1 and referred to a single material plate (AlN) [2]. The flat regions are shorter than the previous case and the modes cannot be anymore identified as symmetric or antisymmetric: the modes will be named hereafter with an increasing number.…”

Guided acoustic wave sensors for liquid environments

“…In [75] experimental results with various SHAPMs in an ST 90°-x quartz plate concerning the influence of temperature, viscosity and the concentration of NaCl and tris(hydroxymethyl) aminomethane (Tris) in aqueous solution are presented: the x, y and z represent the crystallographic axis system; x 3 is the plate normal; the propagation direction of the pure SHAPM is equal to x 2 or x 1 for trigonal or hexagonal crystals. Reproduced from [71]. CC BY 4.0. higher order modes appeared to be more sensitive than the first ones, although they had more transmission losses.…”