Improvement of liquid-phase SH-SAW sensor device on 36° Y-X LiTaO3 substrate

In this paper we describe liquid-phase two-channel Shear Horizontal Surface Acoustic Wave (SH-SAW) sensors to detect conductivity and permittivity of the liquids. In the case of the low-permittivity liquids, the SH-SAWs in the delay-line having an unmetallized propagation area can be degraded owing to the lack of SH-SAW energy concentration of the surface. Then the obtained permittivity and conductivity of the liquids were slightly different from the exact values. In this paper, the delay-line having the electrically-opened thin film metallic-gratings (OP-GR) on the propagation area has been proposed instead of the delay-line having unmetallized propagation area. The OP-GR delay-line gives a good SH-SAW energy concentration of the surface even though low permittivity liquids. The experimental results of the liquid-phase SH-SAW sensors with a center frequency of 30 MHz have been shown.