An apparatus for liquid manipulation, comprising (a) a substrate comprising a first substrate surface; (b) first array of elongated drive electrodes disposed on the first substrate surface, wherein spacing between adjacent elongated drive electrodes of the first array is from 0.005 mm to 10 mm; (c) second array of elongated drive electrodes, perpendicular to the first array, disposed on the first substrate surface and on a first dielectric layer, wherein spacing between adjacent elongated drive electrodes of the second array is from 0.005 mm to 10 mm; (d) the first dielectric layer disposed on the first substrate surface to cover the first array of drive electrodes and to electrically isolate the electrodes of different arrays; (e) second dielectric layer disposed on the first substrate surface to cover the second array of drive electrodes; and (f) an electrode selector for sequentially activating and de-activating one or more selected drive electrodes of the first or second arrays by supplying the actuation voltages to sequentially bias the selected drive electrodes actuation voltages, whereby a droplet disposed on the surface of the second dielectric layer moves along a desired path defined by the selected drive electrodes, wherein all of the electrodes in the first and second arrays can be electrically grounded by the electrode selector; (g) cover plate comprising a plate surface facing the first substrate surface, wherein the cover plate is spaced from the first substrate surface by a distance to define a space between the cover plate and the substrate surface, wherein the distance is sufficient to contain a droplet disposed in the space, and wherein an electrode is disposed on at least a portion of the cover plate surface and is electrically grounded; (h) an electrically insulative, hydrophobic layer disposed on at least a portion of the electrode on the cover plate. (a) a substrate comprising a first substrate surface; (b) first array of elongated drive electrodes disposed on the first substrate surface, wherein spacing between adjacent elongated drive electrodes of the first array is from 0.005 mm to 10 mm; (c) second array of elongated drive electrodes, perpendicular to the first array, disposed on the first substrate surface and on a first dielectric layer, wherein spacing between adjacent elongated drive electrodes of the second array is from 0.005 mm to 10 mm; (d) the first dielectric layer disposed on the first substrate surface to cover the first array of drive electrodes and to electrically isolate the electrodes of different arrays; (e) second dielectric layer disposed on the first substrate surface to cover the second array of drive electrodes; and (f) an electrode selector for sequentially activating and de-activating one or more selected drive electrodes of the first or second arrays by supplying the actuation voltages to sequentially bias the selected drive electrodes actuation voltages, whereby a droplet disposed on the surface of the second dielectric layer moves along a desired path defined by the selected drive electrodes, wherein all of the electrodes in the first and second arrays can be electrically grounded by the electrode selector; (g) cover plate comprising a plate surface facing the first substrate surface, wherein the cover plate is spaced from the first substrate surface by a distance to define a space between the cover plate and the substrate surface, wherein the distance is sufficient to contain a droplet disposed in the space, and wherein an electrode is disposed on at least a portion of the cover plate surface and is electrically grounded; (h) an electrically insulative, hydrophobic layer disposed on at least a portion of the electrode on the cover plate.