Spontaneous uptake of droplets into non-wetting capillaries

In the present study, the spontaneous uptake of droplets into non-wetting capillaries was simulated by using many-body dissipative particle dynamics. The simulated results show that the droplets undergo a spontaneous uptake even for a non-wetting capillary. In contrast to the liquid in a reservoir in which the direction of liquid spontaneous movement in the capillary depends on the wettability, the moving direction of droplets in the capillary relies not only on the surface wettability but also the radius of the droplets. We give an explanation from the viewpoint of force balance. Our results demonstrate that capillary force could be used to drive liquid in microfluidics.