Elasticity and damping ratio measurement of droplets on super-hydrophobic surfaces

The elasticity of the droplet refers to the ability of the droplet in restoring to its original shape and ensuring its strong robustness. The measurement of the droplets' elasticity is vitally important in understanding the characteristics and mechanism of the droplet jumping, spreading, and coalescence. In this paper, we measured the elasticity and damping ratio of droplets with different viscosity. A plate coated with a hydrophobic layer pressed on a droplet, and the elastic force was recorded by an electronic balance. Meanwhile, a mathematical model was constructed to illustrate the change rate of the droplet area with the elastic force. By comparing the influence of volume and viscosity on elasticity, the results showed that work done by pressure converts into surface energy. And the elasticity of the droplet is provided by the surface tension and the damping ratio increases from 0.068 to 0.261.