Design and analysis of a low actuation voltage electrowetting-on-dielectric microvalve for drug delivery applications

This paper presents a low actuation voltage microvalve with optimized insulating layers that manipulates a conducting ferro-fluid droplet by the principle of electrowetting-on-dielectric (EWOD). The proposed EWOD microvalve contains an array of chromium (Cr) electrodes on the soda-lime glass substrate, covered by both dielectric and hydrophobic layers. Various dielectric layers including Su-8 2002, Polyvinylidenefluoride (PVDF) and Cyanoethyl pullulan (CEP), and thin (50 nm) hydrophobic Teflon and Cytonix are used to analyze the EWOD microvalves at different voltages. The Finite Element Method (FEM) based software, Coventorware is used to carry out the simulation analysis. It is observed that the EWOD microvalve having a CEP dielectric layer with dielectric constant of about 20 and thickness of 1 μm, and a Cytonix hydrophobic layer with thickness of 50 nm operated the conducting ferro-fluid droplet at the actuation voltage as low as 7.8 V.