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In order to realize miniature biosensors for real-time, rapid and direct detection, a liquid-phase sensor using shear horizontal surface acoustic waves (SH-SAWs) on quartz is presented. On the sensor chip, there is an SH-SAW delay line that is composed of a transmitting interdigital transducer (IDT), receiving IDT and a biochemical reaction area in between them. The biochemical reaction area is surrounded with epoxy wall to protect the IDTs from liquid. In order to evaluate the performance of an SH-SAW delay-line sensor, C-reactive protein antibodies with different concentrations are provided to the biochemical reaction area. The phase changes in the S21 response of a 250 MHz 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. Furthermore, a concept of one-chip biosensor system that is composed of SH-SAW delay lines for sensing and additional IDTs to excite Rayleigh type SAWs for SAW streaming on a chip. In this paper, one-chip quartz-based liquidphase SH-SAW delay-line sensor systems with pumping and agitating functions using Rayleigh type SAWs are demonstrated.

Hiromi Yatsuda
Takashi Kogai