Recently, we proposed a ring-shaped surface acoustic wave (SAW) resonator sensitive element design, as well as analyzed its characteristics and suggested its optimization strategy, with major focus on their temperature stability. Here, we focus on further optimization of the design to narrow the bandwidth and improve signal detection, while taking into account typical technological limitations. Additionally, the purpose of design optimization and modeling is to check the preservation of operability in the case of lithography defects, which is the most common technological error. For that, we suggest structural alteration of the interdigital transducer (IDT) that leads to its partial fragmentation. Using COMSOL Multiphysics computer simulations, we validate several IDT options and show explicitly how it could be optimized by changing its pin geometry. Based on the results of the study, prototyping and printing of ring resonators on a substrate using photolithography will be carried out.

We propose the use of aluminum nitride (AlN) membranes acting as sensitive elements for the surface acoustic wave (SAW)-based acceleration measurement. The proposed solution is compared against existing prototypes based on the use of quartz (SiO₂)/lithium niobate (LiNbO₃) membranes that are characterized by extensive anisotropic properties. Using COMSOL Multiphysics 5.4 computer simulations we show explicitly that sensitive elements based on less anisotropic AlN membranes overcome both the low sensitivity limitations of SiO₂ and low temperature stability of LiNbO₃. Moreover, AlN membranes exhibit nearly double the robustness against irreversible mechanical deformations when compared against SiO₂, which in turn allows for further 1.5-fold sensitivity enhancement over LiNbO₃ based sensors. Taking into account their acceptable frequency characteristics, we thus believe that the AlN membranes are a good candidate forsensitive elements especially for high acceleration measurements.

Originally, sensors based on surface acoustic waves are fabricated using photolithography, which becomes extremely expensive when a small series or even single elements are needed for the research. A laser thin film local evaporation technique is proposed to substitute the photolithography process in the production of surface acoustic wave based inertial sensors prototypes. To estimate its potential a prototype of a surface acoustic wave gyroscope sensing element was fabricated and tested. Its was shown that the frequency mismatch is no more than 1%, but dispersion of the wave on small inertial masses leads to a spurious parasitic signal on receiving electrodes. Possible ways of its neglecting is discussed.

Оптимальный габаритный параметр кольцевого резонатора на поверхностных акустических волнах

In preceding research endeavors, the frequency characteristics of a ring resonator on surface acoustic waves made of various materials were studied. Investigations encompassed fixation techniques within the housing, the impact of external variables on these components, and the most efficient configuration of the interdigital transducer within the ring resonator to curtail bandwidth. This current study is dedicated to investigating the correlation between sensitivity and the highest measurable acceleration concerning the dimensions of these sensitive elements. Furthermore, it involves assessing the attributes of produced experimental samples to verify the simulation results. The results obtained represent the possibility of creating a micromechanical accelerometer that can be used in the automotive industry as a g-sensor shock, as well as in industries where the numerical value of high overloads is required.

Introduction. Previous works considered the frequency characteristics and methods for fixing sensitive elements in the form of a wave ring resonator on surface acoustic waves in a housing made of various materials, as well as the influence of external factors on sensitive elements. It was found that the passband in such a case is sufficiently wide, which can affect adversely signal detection when measuring acceleration using the sensitive element under development. Therefore, it has become relevant to reduce the sensitive element’s bandwidth by changing the design of the interdigitated transducer (IDT).Aim. To demonstrate an optimal topology for an IDT with a low bandwidth, leading to improved signal detection when acceleration affects the sensitive element.Materials and methods. The finite element method and mathematical processing in AutoCAD and in COMSOL Multiphysics.Results. Nine topologies of IDT are proposed. All these types were investigated using the COMSOL Multiphysics software on lithium niobate substrates, which material acts as a sensitive element. The frequency characteristics are presented. The data obtained allowed an optimal design of the ring resonator to be proposed: an IDT with rectangular pins without selective withdrawal.Conclusion. Self-generation in a ring resonator can be performed by withdrawing no more than one pair of IDTs for 10 or more periods. In this case, the withdrawal of IDTs should be uniform. With an increase in the number of IDT withdrawals, the geometry of the ring resonator is violated, and the wave leaves the structure. The presence of a shared bus keeps the surface acoustic wave inside the IDT structure, and the narrowing of the periods towards the inner part of the structure makes it possible to improve the frequency characteristics of the ring resonator on surface acoustic waves.