Increased droplet coalescence using electrowetting on dielectric (EWOD)

Small-scale electrodes and gaps subjected to repeated short bursts of AC voltage were used to improve droplet coalescence and growth for water harvesting by actively bashing smaller droplets together to form larger ones. Several different electrode patterns were tested under the same conditions. The results indicate that condensation on a cooled flat surface was increased using electrowetting (EW) by accelerating the slow coalescence process where smaller droplets join to form larger droplets and leave behind a dry surface for new droplets to form. A pattern consisting of 100-μm wide interdigitated electrodes separated by 100-μm gaps showed the fastest growth in droplet size. The largest droplets formed with such a pattern had approximately 30 times larger volume than the largest droplets formed on the surface when electrowetting was not applied. Finer patterns exhibited a larger overall condensation rate, where the electrowetting method showed up to a 56% increase in overall water condensation.