Fabrication and characterization of electrowetting on the flexible substrate

Abstract

This paper reports the fabrication of and characterization on EWOD (electrowetting-on-dielectric) devices on flexible substrates of interest to the flexible displays research field. The EWOD devices were fabricated on PET (poly ethylene terephthalate) and PMMA (polymethylmethacrylate) substrates. Au and ITO (indium tin oxide) were used as electrode materials. The wet etching process was developed to not attack plastic flexible substrates. The photo resist was used as an insulator material in EWOD devices due to the deformation of the substrate when the oxide layer was deposited on the plastic substrate. As a hydrophobic layer, cytop was spin-coated on the photo resist. Wetting tests were done with DI water in air environment. In sessile droplet test, the contact angle of droplet changed from 116 to 80 under DC power. Threshold voltage was 20 Vdc. The droplet was oscillated under AC power because of the frequency. The contact angle of droplet began to change at 30Vac and decreased with the increase in AC power. In droplet transporting test, a droplet (0.2 began to be transported at 20Vac and the moving speed increased with the increase of AC power. Droplet transporting did not occur under DC power because of the slower contact angle recovery rate under DC power. copyright © 2007 Materials Research Society.