SH-SAW biosensor on quartz
This paper describes a shear horizontal surface acoustic wave (SH-SAW) immunoassay biosensor on a quartz substrate. The SH-SAW biosensor is a 250MHz SH-SAW delay-line which has a gold surface covered with antibodies. It is important to discuss the detection mechanism of SH-SAW biosensors on quartz. In this paper, the detection mechanism of SH-SAW biosensors are investigated, using three methods of numerical analysis. The first method is a mass loading model analysis. The second method is a viscosity model analysis. The third method is a viscoelasticity model analyasis. A numerical calculation method for SH-SAW propagation characteristics, which is a modified Campbell and Jones method involving the effect of liquid viscosity is applied to quartz. In order to confirm the proposed numerical analysis models, 250MHz SH-SAW biosensors on quartz substrates were tested. The mass, viscosity, and viscoelastic behavior of fluids on SH-SAW biosensors were theoretically and experimentally discussed.
Low-loss SAW filter using internal reflection types of single-phase unidirectional transducer
A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the change of the electromechanical coupling coefficient within a half or one wavelength is described.
Study of Relationship between Cut Angle of Substrate and Characteristics of Surface Acoustic Wave Resonators with Shape-Controlled SiO2
This study provides the relationship between cut angles of the rotated Y–X LiTaO3 (LT) substrate and characteristics of surface acoustic wave (SAW) resonators with shape-controlled SiO2 in the SiO2/Al/LT system. The 32–48° Y-cut of LT is well known as the leaky-SAW (LSAW) cut of LT. The propagation characteristics of an LSAW are affected by the surface condition of the substrate, and the optimum cut of LT should be determined with respect to such condition. In this study, we investigated the dependence of SAW resonator characteristics on the shape of SiO2 and on the cut angle of LT by simulation and experiment. The dependence of the reflection coefficient and coupling factor on the shape of SiO2 is not changed by the cut angle of LT, but the dependence of the quality factor (Q-factor) on the shape of SiO2 is changed by the cut angle of LT. Additionally, the dependence of the Q-factor on the cut angle at resonance frequency was different from that at antiresonance frequency. It was shown that LT with the rotation angle of 39–42° gives the optimal balance in this system.