Electrowetting-driven droplet shrinkage with tunable focus property

Abstract

In this paper, a non-conductive droplet driven by electrowetting (EW) with planar electrode in surrounding fluid is studied. COMSOL is employed to simulate the evolution of droplet shrinkage and the relative experimental setup is established to monitor the evolution of contact angle and height at different voltages. The droplet contracts inward and the corresponding contact angle/height increase when voltage increases. When the voltage ranges from 50 V to 140 V, the variation of the relative contact angles and height reach up to 118.78° and 3.194 mm, respectively. The system of silicon oil and surrounding liquid propylene glycol (PG) acts as a positive lens, whose focal length varies from 87.153 mm to 42.963 mm.