A return electrode monitoring (REM) system for an electrosurgical system is disclosed. The REM system includes circuit components or circuitry for monitoring the magnitude of an interrogation or drive signal, and one or more electrode pads including one or more pairs of split electrode pads. The REM system, while sweeping an interrogation signal over or across a frequency range, monitors the magnitude of the interrogation signal. The REM system determines if there is a frequency shift in the interrogation signal. If there is a frequency shift, the REM system determines the frequency shift and uses it to calculate a reactance value of the impedance. The complex impedance can then be determined. The complex impedance, or at least the reactance value, can be used to determine the capacitive coupling between the patient and pad interface.

A sealing and/or cutting instrument having a thermally active surface or element which may be used to seal and then cut tissue, ducts, vessels, etc., apart. The instrument may include a thermally active surface or element comprised of a conductor covered with a ferromagnetic material. The instrument may contact tissue with one or more surfaces comprised of a non-stick material. A sensor in communication with the instrument may be used to monitor a therapeutic procedure and signal when sealing and/or cutting of a tissue is complete.

A electrosurgical generator and system includes a first radio frequency (RF) source and a second RF source, a first controller configured to output a first control signal to the first RF source to generate a first RF waveform, and a second controller configured to output a second control signal to the second RF source to generate a second RF waveform. The electrosurgical generator further includes a first output port and a second output port configured to provide the respective first RF waveform and the second RF waveform for treatment of tissue.