Materials issues of SAW sensors for high-temperature applications

Abstract

The technology of surface acoustic wave (SAW) devices allows the integration of signal processing and sensor functions within one product. In the past, SAW sensors have been operated at room temperature or 100 C-200 C at most. Material-related problems become obvious if one attempts to increase this operating temperature to a value as high as 1000 C. First experimental results will be presented based on a variation of the metallization and the use of diffusion barriers. It is expected that the use of these specially tailored materials with particular functional properties will lead to a considerable improvement of the lifetime and reliability of SAW sensors and the development of devices resistant to high temperatures as well as high pressures and chemically aggressive environments. The high-temperature characteristics of such novel devices are investigated by finite-element simulation and by experimental deformation analysis. It will also be discussed which assembly, interconnection, and packaging techniques are applicable at 1000 C.

Novel Multilayer SAW Temperature Sensor for Ultra-High Temperature Environments

“…As common passive wireless devices, surface acoustic wave (SAW) devices have attracted widespread attention because of their high operating frequency, digital compatibility, and high reliability [9][10][11]. Traditional SAW devices tend to show performance decline or even complete failure in high-temperature environments [12]. Notably, langasite (LGS) piezoelectric single-crystal materials offer unique advantages over traditional piezoelectric materials under such conditions.…”

Novel AlN/Pt/ZnO Electrode for High Temperature SAW Sensors

“…Many efforts in recent years have been focused on surface acoustic wave (SAW) sensors [ 1 , 2 ], mainly due to their excellent wireless, passive, small, multifunctional quality, and their ability to be widely applied to systems sensing temperature [ 3 ], pressure [ 4 ], and strain [ 5 ] et al With the progress of science and technology, these SAW sensors, which work in high temperature, harsh environments, are in high demand [ 6 ]. The major challenge of SAW sensors operating at high temperatures is to prepare stable high temperature film electrodes, since film electrodes such as Pt [ 7 ], Pt-Rh [ 8 ], Ir-Rh [ 9 ], Ru-Al [ 10 ], W/Mo [ 11 ], W [ 12 ], or Pt-Ni/Pt-Zr [ 13 ] film electrodes, always undergo rapid agglomeration and recrystallization above 700 °C, resulting in the discontinuity of film electrodes, an increase in resistance, and a failure of the SAW sensor.…”

Improvement of High-Temperature Stability of Al2O3/Pt/ZnO/Al2O3 Film Electrode for SAW Devices by Using Al2O3 Barrier Layer

“…Meanwhile, with the progress of science and technology, SAW sensors that operate stably in high temperatures are in high demand [5]. As is widely known, the major challenge in fabricating SAW sensors for operating at high temperatures is to prepare film electrodes which can work stably at high temperatures.…”