Ingress protection for electrosurgical pencil switch

A surgical instrument comprising:

• a switch base having a top surface, a bottom surface, and side surfaces;
• a power bus coupled to the switch base;
• at least one electrical lead coupled to the power bus;
• a membrane disposed over at least the top surface of the switch base and over the power bus sealing the top surface of the switch base;
• and
• a housing defining a proximal end, a distal end, and a switch base cavity between the proximal and distal ends, the housing including a plurality of bulkheads forming a plurality of fluid impermeable seals within the housing and disposed adjacent to at least one of the proximal end or the distal end, a first bulkhead of the plurality of bulkheads forming a proximal fluid impermeable seal proximal of the switch base cavity configured to deter fluid from penetrating a proximal portion of the switch base cavity within which the at least one electrical lead is coupled to the power bus, wherein the plurality of bulkheads includes a proximal bulkhead extending from the housing and engaged to a portion of the membrane that is disposed over a proximal end portion of the switch base.