How to avoid droplet ejection during impact under an electric field.

This article investigates the electrostatic stability of droplet impact behaviors—specifically pancake and ring bouncing—on superhydrophobic surfaces within electric fields (EFs). It demonstrates that at high Weber numbers (We), droplets impacting micropillar-arrayed or cylindrical protrusion superhydrophobic surfaces rebound in pancake or ring shapes, respectively, effectively avoiding the stretching phase that forms sharp tips responsible for electrostatic force-induced ejection or breakup. Experimental and numerical analyses reveal that these special rebound modes prevent significant charge accumulation and electric field distortion on the droplet surface, maintaining electrostatic stability even under strong electric fields. The findings suggest that such droplet behaviors enable non-loss droplet transport and have potential applications in optimizing outdoor electrical device design.