The Transmission and Attenuation Characteristics of Saws at the Edge of Discontinuous Media and the Application of Droplet Jetting

This paper presents experimental and numerical studies on the transmission and attenuation characteristics of surface acoustic waves (SAWs) in the continuous medium on the polished surface and the discontinuous medium at the cutting edge of the SAW device, and the corresponding application of the formed acoustic wavefield on micro-scale droplet jetting. Simulating the vibration of Rayleigh SAWs in 128° Y-X LiNbO₃ substrate, the transmission and loss characteristics of the SAWs on the surface and in the body of the piezoelectric substrate are characterzed. The absorption gel is used to absorb the acoustic waves propagated in one direction from the upper surface of the piezoelectric substrate, and the droplet jetting experiments on the lower/upper surface of the piezoelectric substrate are carried out and compared, which shows similar droplet jetting characteristics with different input electric power to IDTs. The transmission efficiency of SAW from upper surface to lower surface of piezoelectric substrate is determined by both the thickness of the piezoelectric substrate and the wavelength of the SAW. Unlike the traveling wave generated on the upper surface of the piezoelectric substrate, where the interdigital transducers (IDTs) are located, a stable standing wave acoustic field can be formed on the lower surface of the double-polished piezoelectric substrate to jet a droplet in vertical direction.