abstract |
In an electrosurgical system which is operable within the frequency range of from 100kHz 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. |