Liquid sensor probe using reflecting SH-SAW delay line

A new liquid sensor probe has been designed by using SH-SAW device. Shear horizontal mode surface acoustic wave (SH-SAW) has a unique characteristic of complete reflection at the free edges of the substrate. The SH-SAW are excited on a 36° YX LiTaO3 and the right angle edge of the substrate has been used to reflect the SAW. Multi-channel reflecting SAW delay lines were constructed on the substrate. Both the phase and amplitude of the SH-SAW reflected from the edge were measured as a sensor response. Several experiments were performed to verify the edge reflection type SAW sensor in liquid phase. A sensing system configuration is also suggested for the effective operation of the sensor probe. An electronic circuits system for accurately measuring the phase characteristics of the reflected wave and for detecting the output from the multi-channel SAW sensor probe was shown.