Electrosurgical instrument and an electrosurgery system including such an instrument

摘要

In an electrosurgical system which is operable within the frequency range of from 100 kHz to 50 MHz and which has a handheld instrument with an elongate instrument shaft, the distal end of the shaft carries a bipolar electrode assembly for use in a conductive fluid field. The electrode assembly has an active electrode and, set back from the active electrode, a return electrode coated with an insulative dielectric layer. The insulative layer may be made of a plastics or a ceramic material and acts as the dielectric of a capacitor when the electrode assembly is immersed in the conductive fluid. One of the effects of the insulative layer is to provide a more uniformly distributed electric field over the return electrode than is obtained with an exposed return electrode, yielding improved tissue desiccation and vaporisation characteristics. The active electrode may have a similar dielectric covering.