Saw delay lines as wireless sensors for industrial applications

The paper gives a review on SAW (Surface Acoustic Wave) sensing applications and on the underlying sensing principles with the focus on reflective delay lines. SAW devices are used to detect physical quantities like temperature, pressure and strain and applied as RFID-tags (Radio Frequency IDentification), especially in harsh environments. We describe various wireless temperature sensors with and without ID functionality designed for different applications in steel industry like CMC (continuous mould casting), refractory slide gates and tagging of slag vessels as well as for the long range temperature reading of power lines. We also give an example for pressure measurements based on a membrane sensor design.