IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Apr;65(4):657-664. doi: 10.1109/TUFFC.2018.2797093.
Surface acoustic wave (SAW) sensors are steadily paving the way to wider application areas. Their main benefit consisting in the possibility of wireless interrogation with the radio frequency interrogation signal being the only energy source for the reradiated signal. This feature is getting more and more attractive with the growing demand in monitoring multiple industrial objects difficult to access by wired sensors in harsh environments. Among such wider applications, the possibility of making measurements of temperature, deformation, vibrations, and some other parameters at temperatures in the range of 300 °C-1000 °C look quite promising. This paper concentrates on specific features of the SAW resonator-based sensors operation at this temperature range. High-temperature influences the material choice and thus the properties of SAW resonators design peculiarities intended for use at high temperature. It is suggested that preferable designs should use synchronous resonators with relatively thick electrodes (10% of wavelength) based on Ir or Pt alloys while benefiting from the possibilities of specific designs that could reduce the negative impact of thick electrodes on the manufacturing in quantity. This solution benefits from lower resonance frequency scatter because of the automatic compensation of SAW velocity decrease due to electrode metallization ratio increase. This compensation originates from the resonance frequency increase that is related to the decrease of the Bragg bandwidth defined by the reflection. It is shown in modeling examples that the value of metallization ratio at which this compensation occurs is close to 65%-70%.
表面声波（SAW）传感器正在稳步开拓更广泛的应用领域。它们的主要优势在于可以通过射频询问信号进行无线询问，而射频询问信号是再辐射信号的唯一能量源。随着对在恶劣环境中难以通过有线传感器进行访问的多个工业对象进行监测的需求不断增长，这种特性变得越来越有吸引力。在这些更广泛的应用中，在 300°C-1000°C 的温度范围内测量温度、变形、振动和其他一些参数的可能性看起来非常有前景。本文专注于在该温度范围内基于 SAW 谐振器的传感器操作的特定特征。高温会影响材料选择，从而影响设计用于高温的 SAW 谐振器的特性。有人建议，优选的设计应使用基于 Ir 或 Pt 合金的同步谐振器，其电极较厚（波长的 10%），同时受益于特殊设计的可能性，这些设计可以减少厚电极对批量制造的负面影响。由于电极金属化比增加导致 SAW 速度降低的自动补偿，这种解决方案得益于较低的共振频率散射。这种补偿源于由于反射定义的布拉格带宽减小而导致的共振频率增加。在建模示例中表明，发生这种补偿的金属化比接近 65%-70%。
