The present invention relates to a microfluidic or millifluidic device (1) comprising: —a support (2) made at least partially of a dielectric material, the support (2) comprising a first inlet (21a) adapted to be connected to a first reservoir containing gas, a second inlet (21b) adapted to be connected to a second reservoir containing liquid, an outlet (22) adapted to be connected to a receiver container containing gas and/or liquid, and a main microchannel or millichannel (3) present in the dielectric material allowing the liquid and the gas to flow from the inlets towards the outlet, —one or several ground electrode(s) (4) embedded in said dielectric material and extending along the main microchannel or millichannel (3), and —one or several high-voltage electrode(s) (5) embedded in said dielectric material and extending along the main microchannel or millichannel (3), wherein the high-voltage electrode(s) (5) and the ground electrode(s) (4) are located on opposite sides of the main microchannel or millichannel (3) so as to be able to generate an electric field inside the main microchannel or millichannel (3). The present invention relates also to a method for generating a plasma in a continuous manner using such a microfluidic or millifluidic device (1).