Electrically-insulative shafts, methods of manufacturing electrically-insulative shafts, and energy-based surgical instruments incorporating electrically-insulative shafts

A surgical instrument, comprising:

• a housing;
• at least one electrode operably coupled to the housing and configured to supply energy to tissue;
• and
• an electrically-insulative shaft extending at least partially between the housing and the at least one electrode, the electrically-insulative shaft including:
• an outer tube formed from an electrically-insulative material;
• an inner tube formed from an electrically-insulative material;
• and
• an intermediate tube disposed between the outer and inner tubes, the intermediate tube formed from an electrically-conductive material and being electrically isolated within the outer and inner tubes from the remainder of the surgical instrument,
• wherein distal ends of the outer and inner tubes extend beyond a distal end of the intermediate tube and are joined to one another to enclose the distal end of the intermediate tube therebetween.

A method of manufacturing an electrically-insulative shaft for a surgical instrument, comprising:

• providing an electrically-insulative outer tube, an electrically-insulative inner tube, and an electrically-conductive intermediate tube;
• joining distal ends of the outer tube and the inner tube with one another to form a joint;
• inserting the intermediate tube into an annular gap defined between the outer and inner tubes such that the distal ends of the outer and inner tubes extend beyond a distal end of the intermediate tube and enclose the distal end of the intermediate tube therebetween;
• and
• enclosing a proximal end of the intermediate tube to electrically isolate the intermediate tube within the outer and inner tubes.