A Wireless Surface Acoustic Wave Temperature Sensor Using Langasite as Substrate Material for High-Temperature Applications

A wireless surface acoustic wave (SAW) temperature sensor was produced using langasite single crystal as a piezoelectric substrate. The properties of both solid-electrode and split-electrode interdigital transducers (IDTs) were studied by fitting the admittance curves. A miniature antenna was used and the impedance matching technique between the antenna and the IDT was investigated. The temperature characteristic in the temperature range of 20–700°C was measured. The results showed that both the SAW chip and the antenna functioned in this temperature range.