Methods and apparatus for focused bipolar tissue ablation using an insulated shaft

A bipolar tissue ablation probe for creating a lesion within a target tissue comprising:

• a proximal electrode array configured for moving from a retracted configuration to a deployed configuration by proximal retraction;
• a distal electrode array configured for moving from a retracted configuration to a deployed configuration by distal advancement;
• a shaft carrying the proximal and distal electrode arrays, wherein the shaft has an electrically insulative portion that separates the proximal and distal electrode arrays, the shaft having a distal point of deployment for the distal electrode array and a proximal point of deployment for the proximal electrode array;
• and
• wherein the proximal electrode array and the distal electrode array each comprise respective everting needle electrodes when in the deployed configuration, wherein the everting needle electrodes of the proximal electrode array and the distal electrode array are partially coated with an insulating material along a length of the everting needle electrodes from their respective points of deployment.