Dynamic characteristics of vibrated droplets on the one-tier and two-tier surface

Dynamic characteristics of droplets on the one-tier surface, which was a micropillared hydrophobic surface fabricated by lithography and two-tier surface, which was a micro-nano hydrophobic surface replaced by dry lotus leaf were studied under vertically vibration. Our experiments shown that the two-tier surface led to a decrease of the critical amplitude (which was required to make the droplets separated from the surface) than the one-tier surface at each given frequency. Meanwhile, droplets on the two-tier surface need lower vibration energy to separate from the surface. But the vibration morphology and mode of the droplet on the two-tier surface are rather more complicated. The physical mechanism of droplet separation by vibration was presented and then analyzing the experimental phenomenon in combination with surface mechanics and kinetic energy. We demonstrate that the length of the triple contact line is an important parameter in the form of droplet vibration mode and morphology.