Analysis of contributions of nonlinear material constants to stress-induced velocity shifts of quartz and langasite surface acoustic wave resonators

Abstract

Stress-induced surface acoustic wave velocity shifts are analyzed for langasite (LGS) SAW resonators. The analytical methodology has been verified by comparing experimental results and analytical results for quartz resonators. LGS SAW resonators with Euler angles which are most sensitive and least sensitive to diametrical forces are determined and their applications in force sensors and resonators with minimum acceleration sensitivity are discussed. Sensitivity of the analytical results to different groups of nonlinear material constants is discussed; it was found that for specific configurations, failure to include the third-order piezoelectric constants, dielectric constants and electrostrictive constants may lead to a significant calculation error. Surface acoustic waves propagating on an LGS square plate subject to bending moment along the propagation direction and normal to the propagation direction are analyzed; it was found that the average momentinduced velocity shift of LGS resonators are comparable to quartz resonators. Analyses of the sensitivity of the results to different groups of nonlinear material constants shows that for some specific wave propagation directions, failure to include the third-order piezoelectric constants, dielectric constants, and electrostrictive constants may lead to large errors.

Langasite-based surface acoustic wave resonator for acetone vapor sensing

“…The sensing patterns are consistent, where a rigorous proportionality between frequency drift and acetone concentration can be observed throughout the operating temperature, from RT to 200°C. Table 1 shows the comparison of acetone vapor sensitivity between the proposed LGS SAW resonator sensor and other reported resonator sensors [49][50][51][52][53]. From table 1, it can be seen that, compared to the reported VOC sensors, the proposed sensor in this paper possesses a comparable sensitivity, which can be substantially employed for low concentration acetone vapor sensing.…”

“…The principle of acetone sensing is derived on the basis of mass loading of a typical SAW sensor, which is also known as mass-frequency effect of a SAW resonator, where the resonant frequency drift is deemed as dependent of its SAW and wave velocity [36,[48][49][50][51][52] and can be described as…”

“…where f 0 is the resonant frequency of SAW resonator, l 0 is the wavelength that is determined by the interdigital transducer pitch size [36], and v 0 is the SAW velocity that is determined by the material properties that can be significantly affected by the mass loading on the surface [50][51][52], and the relationship between the mass loading and the SAW velocity change is described in equation…”

Optimizing crystal cut and the frequency shift of a langasite surface acoustic pressure sensor with new FEM approach

“…Their formulation, however, disregarded the nonlinear material constants. In a comprehensive analysis by Zhang [14], a crucial refinement has been introduced to augment the precision of analytical outcomes. Zhang's analytical results were contingent upon the assumption of a uniform stress and strain field throughout the resonator, with stress magnitudes computed at its center and extrapolated uniformly across its entirety.…”

“…The perturbation integral utilizes as a numerical tool employed to compute these shifted values in SAW frequencies. The integral formula is described by the following equations [14]:…”