Observation of Surface Acoustic Wave Propagation on a Quartz Ball with Concave Proximate Electrodes

We evaluated the characteristics of roundtrip propagation on a ball surface acoustic wave (SAW) device by controlling the approach of electrodes to the quartz ball. In order to investigate the relationship between the interdigital transducer (IDT) position and the exponential attenuation in the roundtrips of SAW, we brought a concave glass plate with an IDT towards the equatorial belt (Z-axis cylinder) of the quartz ball, and transmitted and received a SAW. In this study, the precision of the apparatus was improved, and as a result, it was found that roundtrip of SAW attenuates exponentially when the IDT is at a certain position. The specific positions were not always at the Z-axis cylinder but distributed around it with the meander belt with a period of 120°. By fabricating an IDT at such positions, it is expected that the performance and reproducibility of ball SAW sensors will be enhanced.