On-demand trajectory control of continuously generated airborne microdroplets

A technique to control the trajectory of in-flight microdroplets is described. The localized electric field generated by a needle electrode applies the dielectrophoretic force to the droplet to deflect its trajectory. Deflection by as much as 0.2 rad can be achieved, sufficient for industrial use. Moreover, highly selective control among droplets in a stream was demonstrated with the electric field modulations of 10 μs, which corresponds to the sorting speed of 105 s−1. In contrast to the conventional electrostatic control, the proposed technique is effective also for insulating liquids, allowing it to be applied to a wider range of materials.