Droplet Condensation and Actuation via Surface Acoustic Waves on Lubricant Infused Surfaces

Abstract

Both lubricant-infused surfaces and surface acoustic waves have been studied for their applicability to the field of microfluidics. However, combining the use of the two technologies has not been thoroughly explored. Specifically, this research aims to build off of the work done with single droplets last semester to characterize the way surface acoustic waves cause condensed droplets to behave over a range of wave frequencies and amplitudes, as well as droplet sizes, for possible heat transfer applications. From this study, it is clear that there are four distinct modes of droplet actuation for a given frequency, depending on their size. Large droplets (high diameter) actuate freely, while a range of smaller droplets will not move at all. Droplets that are smaller still will start to move again to a point, while the smallest droplets observed did not move, but did evaporate more quickly when exposed to surface acoustic waves. The exact mechanisms driving this behavior are not currently understood, but still this research shows promise, as further developing an understanding of these phases of droplet movement could allow for greater control in microfluidic applications.