An electrofluidic device includes first structural layer and second structural layer. First structural layer includes first substrate; and first electrode and second electrode on the first substrate. The second electrode has an indent region surrounding and without contacting first electrode. First hydrophobic layer is at least over the second electrode. Second structural layer at one side of the first structural layer with a gap includes second substrate and groove structure layer. The groove structure layer includes an indent groove, corresponding to the indent region of the second electrode. Second hydrophobic layer is over the groove structure layer. Polar fluid is disposed in the indent groove and remains in contact with the first electrode. Non-polar fluid is disposed in the gap between the first and second structural layers.