Microfluidic device based on surface acoustic wave

Microfluidic systems can be implemented for miniaturization of chemical and biological processes on a sub-millimeter scale. In this study, surface acoustic waves (SAW) were used to actuate small droplet (from 2 to 20 μl) on planar surface of a piezoelectric substrate. In order to improve the droplet displacements, a 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 = 100 W and PR = 400 mT. This film has 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 demonstrates a periodical phenomenon at a frequency of 120 Hz for pure water.