Ultrasonic and electrosurgical devices

A surgical instrument, comprising:

• an ultrasonic generator;
• a radio frequency (RF) generator;
• an ultrasonic transducer;
• a waveguide comprising a proximal end and a distal end, the proximal end coupled to the ultrasonic transducer and one output of the RF generator;
• an end effector configured to cut and seal tissue, the end effector comprising an ultrasonic blade and a clamp arm, wherein the ultrasonic blade is mechanically coupled to the distal end of the waveguide and electrically coupled to the waveguide, the clamp arm comprising a movable jaw member electrically coupled to another output of the RF generator such that an electrical current can pass through the movable jaw member and the ultrasonic blade through tissue located between the movable jaw member and the ultrasonic blade;
• and
• a single electrical switch electrically coupled to the RF generator and the movable jaw member, wherein the single electrical switch is operable in at least two independent states, wherein in a first state the single electrical switch is configured to electrically couple the ultrasonic generator to the ultrasonic transducer to cause the ultrasonic blade to activate ultrasonically to deliver ultrasonic energy only and wherein in a second state the single electrical switch is configured to electrically isolate the ultrasonic transducer from the ultrasonic generator and to electrically couple the RF generator to the movable jaw member through an electrical conductor to cause RF electrical current only to flow through the tissue located between the ultrasonic blade and the movable jaw member, wherein the single electrical switch is operable to cause the surgical instrument to deliver electrical current only from the RF generator to the movable jaw member for a first period, and to cause the surgical instrument to deliver ultrasonic energy only to the ultrasonic blade for a second period without input from a clinician, and wherein the surgical instrument is configured such that the second period occurs after the first period in order to seal tissue before cutting tissue.