A cartridge assembly to couple an electrosurgical device to treat tissue with an electrosurgical unit includes a cartridge member to operate with a power delivery apparatus of the electrosurgical unit and a fluid delivery apparatus of the electrosurgical unit. An electrosurgical unit includes a power delivery apparatus and a fluid delivery apparatus arranged to operate with a cartridge member to be located in a cartridge receptacle of the electrosurgical unit. An electrosurgical device includes a first electrode spaced alongside the second electrode, with each electrode having a blade shaped member. Each blade shaped member has opposing sides bounded by edges, with the edges having a medial edge and a lateral edge. At least one fluid outlet is adjacent each blade shaped member, and each fluid outlet is in fluid communication with a fluid passage. The device can be operated as either a bipolar device or a monopolar device and includes a switch to inhibit capacitive coupling to one of the electrodes when the other electrode is used in monopolar fashion.