LiNbO3-Based SAW Sensors Capable to Measure up to 1100°C High Temperature

High temperature measurement of the rotating parts in aero-engine system requires wireless passive sensors. Surface acoustic wave (SAW) devices capable of measuring high temperature wirelessly are therefore ideal for these extreme scenarios where wired sensors are not applicable. In this article, SAW sensors built on the LiNbO
₃
substrate which can measure up to 1100 °C with a good repeatability and endurance are reported. The platinum IDT and LiNbO
₃
substrate were effectively protected by a SiO
₂
passivation layer to ensure the functionality and stability of the SAW devices under extremely high temperature. Distinct linearity of f
₀
vs. temperature, together with the temperature durability of the SAW sensors were verified by conducting various high-temperature RF tests. Such a SAW sensor attached with an embedded near-field antenna was also formulated to enhance the wireless transmission quality for future high-temperature remote sensing system.