Electrohydrodynamic repulsion of droplets falling on an insulating substrate in an electric field

Control technique for charged droplets, named as electrohydrodynamic droplet repulsion (EDR), is reported. Charged droplets emitting from a capillary and falling down toward an insulating substrate are deflected from their intended impact point due to the like polarity of previously fallen droplets. The mechanism for this potentially critical phenomenon is explained by applying a theoretical model describing the balance between gravitational and Coulomb forces acting on a droplet. The parametric conditions for the EDR are subsequently presented.