Surface acoustic wave microfluidic device

Microfluidic systems can be implemented for miniaturization of chemical and biological processes on a sub- millimeter scale. In this study, Surface Acoustic Waves (SAW) was used to actuate small droplet (from 2 to 20 µl) on planar surface of a piezoelectric substrate. In order to improve the droplet displacements, an hydrophobic film was deposited on the LiNbO3 substrate. We have deposited by plasma enhanced chemical vapor deposition a-CFX film. All those films were compared to a spin coated PVDF, the best hydrophobic film was realised for PG= 100W and PR=400mT. This film have a sliding force around 85 µN. We studied the effect of different viscosities by using water/glycerol mixtures. This device propelled a water droplet at 40 mm/s, while the velocity of a glycerol droplet will not exceed 2 mm/s. The study of the droplet motion by a high- speed acquisition camera demonstrate a periodical phenomenon at a frequency of 120 Hz for pure water.