Composite Dielectrics and Surfactants for Low Voltage Electrowetting Devices

In this work electrowetting operation at <12 V has been achieved through implementation of composite dielectrics and surfactants. The composite dielectrics consist of A₁₂O₃ and Si₃N₄ covered by a thin film of hydrophobic Cytop fluoropolymer. These composite dielectrics exhibit higher capacitance and therefore lower voltage electrowetting operation. Atomic layer deposition of A₁₂O₃ and plasma-enhanced chemical vapor deposition of Si₃N₄ were chosen because they can be deposited at low temperature, are pin-hole free, and because they can be conformably coated on 3D surfaces. Surfactants were also explored to lower the water/oil interfacial surface tension and thereby further reduce the voltages required for electrowetting. These results are important for continued development of arrayed electrowetting optics for displays and beam steering applications.