An apparatus comprising a mechanical-to-electrical energy converting device having a plurality of electrodes and a fluidic body which comprises spatially separated conductive and dielectric liquid regions. Said fluidic body is configured to reversibly move as a whole with respect to said plurality of electrodes under the influence of a mechanical force. Each cycle of said reversible motion of said fluidic body causes multiple alternations of the amount of electrical charge accumulated by the electrodes, whereby generating electrical current flow between said electrodes.