Liquid Sensor Using SAW and SH-SAW on Quartz

One-chip sensor system using two different acoustic waves on ST-cut quartz is presented; one is shear horizontal surface acoustic wave (SH-SAW) and the other is surface acoustic wave (SAW). On the sensor chip, there is a SH-SAW delay-line that is composed of a transmitting interdigital transducer (IDT), receiving IDT and a biochemical reaction area in between them. And there is another IDT on the sensor chip, that can excite a Rayleigh type SAW to the biochemical reaction area in the direction normal to the SH-SAW propagation direction. In order to evaluate the performance of the SH-SAW delay-line sensor, C-reactive protein antibodies with different concentrations are provided to the biochemical reaction area. The phase change in the S21 response of the SH-SAW delay-line at a fixed frequency are measured on real-time and it is confirmed that different phase changes are obtained for different antibody concentrations. On the other hand, the one-chip quartz- based liquid-phase SH-SAW delay-line sensors with pumping and agitating functions using SAW are demonstrated.