Surgical instruments with articulating shafts

An end effector of a surgical instrument comprising:

• a shaft extending along a longitudinal axis;
• and
• a curved ultrasonic blade positioned within the shaft and translatable relative to the shaft along the longitudinal axis;
• wherein the curved ultrasonic blade comprises a proximal portion that is curved in a first direction away from the longitudinal axis, an intermediate portion that is curved in a second direction away from the longitudinal axis and opposite the first direction,
• wherein the curvature of the proximal portion and the curvature of the intermediate portion both comprise at least one of a node or an anti-node that occurs at a point of tangency when the ultrasonic blade is driven at a resonant frequency.

A system comprising:

• a generator configured to delivery ultrasonic energy;
• and
• a surgical instrument coupled to the generator, the surgical instrument comprising:
• a shaft extending along a longitudinal axis;
• and
• an end effector configured to treat tissue, the end effector comprising a curved ultrasonic blade positioned within the shaft and translatable relative to the shaft along the longitudinal axis,
• wherein the curved ultrasonic blade comprises a proximal portion that is curved in a first direction away from the longitudinal axis and an intermediate portion that is curved in a second direction away from the longitudinal axis and opposite the first direction,
• wherein the ultrasonic blade is manufactured such that the curvature of the proximal portion and the curvature of the intermediate portion are balanced to both have a vibrational mode purely in the direction of the longitudinal axis.