  We show here that ac electrowetting (ac-EW) with structured electrodes can be
used to control the gravity-driven shedding of drops condensing onto flat
hydrophobic surfaces. Under ac-EW with straight interdigitated electrodes, the
condensate drops shed with relatively smaller radii due to the ac-EW-induced
reduction of contact angle hysteresis. The smaller shedding radius, coupled
with the enhanced growth due to coalescence under EW, results in increased
shedding rate. We also show that the condensate droplet pattern under EW can be
controlled, and the coalescence can be further enhanced, using interdigitated
electrodes with zigzag edges. Such enhanced coalescence in conjunction with the
electrically-induced trapping effect due to the electrode geometry results in
larger shedding radius, but lower shedding rate. However, the shedding
characteristics can be further optimized by applying the electrical voltage
intermittently. We finally provide an estimate of the condensate volume removed
per unit time in order to highlight how it is enhanced using ac-EW-controlled
dropwise condensation.
