SAW Static Strain Sensor for High Temperature Applications

The measurement of static strain in harsh environment, in particular at temperatures beyond 100ºC, is highly desirable in multiple applications such as power plants, industrial manufacturing, and aerospace. The aforementioned industries have a high demand for small, robust, stable sensors that can operate wirelessly, without a battery or power source, and require minimal maintenance for structural health monitoring and condition based maintenance. The technologies that currently exist face multiple challenges related to sensor endurance, size, complexity, and system integrability. Surface acoustic wave (SAW) technology is a technology that has shown promise in a multitude of sensing applications because of its characteristics such as small size, ease of mass production, robustness, battery-free, and wireless capability. In this research work, SAW sensors fabricated using thin film fabrication techniques on langasite employing platinum alloy based electrodes have been exposed to temperatures up to 1000ºC and have shown excellent endurance and a high degree of stability. These sensors have been calibrated as strain sensors up to 400ºC using a finite element model due to the inexistence of reliable strain sensors at the targeted temperatures. In addition, a temperature compensation scheme employing a two sensor configuration was used to mitigate the effects of temperature interference. The results of this research work illustrate the viability of langasite based SAW sensors as stable and reliable high-temperature static strain sensors for harsh-environment applications.

Faculty Mentor: Mauricio Pereira da Cunha