Influence of surface contact angle on uphill motion of droplets due to electostatic actuation

Abstract

Manipulation of fluids in smaller scales has become an extensive field of research for miniaturization of devices in order to cope with the growing demand of modern human civilization. Among other techniques, electro-wetting is the well accepted due to its relatively higher precision and reliability. There are various parameters which could influence electro-wetting process; type of surfaces, whether hydrophobic or hydrophilic is one of them. Hydrophilic surfaces retains a lower contact angle, when get in touch with a liquid droplet; whereas, hydrophobic surface maintains a higher contact angle. In the present study influence of surface contact angles on droplet motion along inclines has been investigated in an analytical approach. A momentum equation which could comprise the effect of contact angle change is solved to study the influence of different contact angles. The contact angle has been varied from 30–120º. The variation of velocity has been analysed for a voltage range of 0–100 V. It has been observed that increase in droplet foot print causes enhancement in actuation force for climbing.