We successfully manipulate dielectric (silicone oil) and conductive (water) droplets by dielectrophoresis (DEP) and electrowetting on dielectric (EWOD) on a digital microfluidic chip. Encapsulated droplets with different volumes of oil shell and water core are formed by merging two quantitatively created oil and water droplets. Transportations of the encapsulated droplets of different core-shell ratios with silicone oil of various viscosities are examined. The driving voltages to transport the encapsulated droplets at different velocities are measured. Furthermore, the evaporation of the water in the encapsulated droplets is reduced. The relation of the evaporation rate to the core-shell ratio and the viscosity of the oil are discussed.