Abstract
Aqueous microdroplets are challenging objects for photoassisted manipulation techniques based on lithium niobate (LN) substrates. In this paper, we demonstrate a successful photovoltaic manipulation of water microdroplets on LN substrates coated with a hydrophobic film. Through the analysis of the dynamic process of the photovoltaic manipulation and the simulation of the electrostatic distribution around the microdroplet-substrate interface, the electrowetting mechanism is suggested to account for the photovoltaic manipulation of water microdroplets. Both the hydrophobicity and the large electrostatic energy capability of the coated film are emphasized for producing a sufficient unbalanced hydrostatic pressure required by the steady water-microdroplet actuation.