Movement of a droplet on a structured substrate: A dissipative particle dynamics simulation study

Abstract

The last decade has witnessed the explosive development of microfluidic systems. Droplet manipulation is one of the crucial technologies in design and optimization of microfluidic devices. In the present study, dissipative particle dynamics is applied to investigate the movement of a liquid droplet actuated by a constant force on structured substrate with different wetting properties ranging from hydrophilic to hydrophobic. By monitoring the variation of the advancing contact angle and the front position of droplet, the characteristics of the droplet motion is analyzed in detail. Results indicate that there exists an optimal structure for which the droplet has a largest speed. Additionally, the influences of wettability gradient, thermal fluctuation and external force are discussed. We find thermal fluctuation is helpful for the movement of droplet.