Direct Measurement of Impacting Force Between a Droplet and a Superhydrophobic Blade

In this study, we propose and realize, for the first time, a MEMS-based measurement system that allows the direct measurement of the impacting force between a droplet and a thin superhydrophobic blade. The system consists of a piezoresistive cantilever that partially supports the thin blade. The force acting on the blade can be derived from the cantilever's resistance change. We found that when the impact velocity is higher than a critical value, the droplet is cut into two droplets by the blade, and the integration of the impacting force is proportional to the size of the smaller droplet resulted after the cutting. The findings in this study will help develop a theoretical model describing the dynamics of a droplet impacting slender objects such as fiber and blade.