Exploring the behaviour of water nanodroplet on a coplanar electrowetting‐on‐dielectric: a molecular dynamics approach

Abstract

Molecular dynamics simulation has been used to investigate the behaviour of a water nanodroplet on a hydrophobic surface under an applied electric field. The model system mimics a typical electrowetting-on-dielectric experiment of an open-plate coplanar electrodes system. Given the various strengths of the electrode-induced field, variations in contact angle of the droplet, hydrogen bonding and diffusion coefficient of the water molecules are disclosed. Their main findings are: (i) nanodroplet displays asymmetric electrowetting in contact angle measurement; (ii) water molecules and the entire droplet are slightly positively biased; (iii) more water hydrogen bonds are maintained in the positive side, in both the first and the second hydration layer to the surface; and (iv) water diffusion is higher in parallel to the surface than the normal direction.