The invention relates to a device 1 for applying an electric field to a suspension of cells, cell derivatives, organelles, sub-cellular particles and/or vesicles, comprising at least one chamber 6 which comprises at least two electrodes 4, 5 and at least one separating element 13 which is movable within the chamber 6 between two terminal points 14, 15 and, if it is in a position between the terminal points 14, 15, separates at least one first compartment 26 of the chamber 6 from at least one second compartment 27 of the chamber 6. According to the invention each compartment 26, 27 is designed to hold the suspension and comprises at least one port 7, 8, 10, 11 for charging or discharging the suspension, so as to discharge an aliquot of the suspension from the chamber 6 and at the same time charge a further aliquot of the suspension into the chamber 6, wherein the separating element 13 is moved in a second direction opposite to a first direction, and wherein the separating element 13 separates the aliquots from each other.
