Shear horizontal surface acoustic wave induced microfluidic flow

Abstract

In this letter, we demonstrate that surface acoustic waves (SAWs) excited on 36°Y-X LiTaO3 have both Rayleigh and shear horizontal components, which can result in different acoustic streaming patterns in micro-droplets. The shear horizontal surface acoustic wave streaming pattern exhibits a quasi-stable counterflow in the SAW propagation direction with velocities of up to 16 mm/s, with minimal damping observed within the droplets. A pumping function was realized at a threshold power of 30 dBm with a large rotation vector on hydrophobically treated devices.

Vertical jetting induced by shear horizontal leaky surface acoustic wave on 36° Y-X LiTaO3

“…4 13 In addition, the mechanisms of these SH-SAW based microfluidic functions have not been well explained.…”

“…12 Theoretically energy from a pure shear wave is difficult to be strongly dissipated into an ideal Newtonian liquid, however, most of the shear waves generated on the piezoelectric materials (such as 36° Y-X LiTaO3) are quasi-shear waves which are accompanied with small longitudinal or compression components, and might lead to acoustic energy dissipation into liquid. Previously, there are some reports that the SH-SAW or Love mode SAWs generated on 36° Y-X LiTaO3 device could be used to manipulate droplets for acoustic streaming/pumping 13 and nebulization. 14 However, SH-SAWs showed poor efficiency of droplet later movement and then were less interesting in comparison to Rayleigh waves.…”

Rayleigh and shear-horizontal surface acoustic waves simultaneously generated in inclined ZnO films for acoustofluidic lab-on-a-chip

“…The coupling energy and momentum induced by the interfacial interaction of the viscous liquid with the SH-SAWs is very weak. At a very higher power of tens of watts, large vertical pressure gradient is generated, resulting in very weak random streaming patterns, which has been reported in the literature [42,47,48]. Figure 6a shows a schematic illustration of the system that comprises a PDMS chamber with the silica-coated IDTs of the ZnO SAW device.…”

Focusing surface acoustic waves assisted electrochemical detector in microfluidics

“…In comparison with other external disturbances, surface acoustic waves (SAWs) are suitable tool of fast and efficient inducing fluid motion in microfluidics device without the need for moving parts . SAWs are sound waves that propagate on the surface of an elastic material .…”