The present invention relates to an optical element, used e.g. in an electrowetting display device comprising a number of pixels, arranged in an array. Each optical element comprises a cell filled with a polar conductive fluid (5), such as a water solution, and a non-polar fluid (6), such as an oil. The cell further comprises first and second planar electrodes (7, 10), covered with first and second hydrophobic layers (8, 11). By applying a voltage between on one hand the first fluid and on the second hand alternately the first or second electrodes (7, 10), the oil (6) is forced to migrate between the first and second hydrophobic layers (8, 11). Thus a bi-stable, energy efficient optical element is provided.