Surgical instrument with non-clamping sensor feedback

A method of determining a non-clamping force against at least one of an ultrasonic blade or a clamp arm of an ultrasonic surgical instrument, wherein the ultrasonic surgical instrument includes:

• (a) an end effector, having:
• (i) an ultrasonic blade, and (ii) a clamp arm pivotally secured relative to the ultrasonic blade and configured to move from an open position for receiving a tissue and a closed position for clamping the tissue against the ultrasonic blade;
• (b) a shaft assembly extending proximally from the end effector, wherein the shaft assembly has:
• (i) a tube, (ii) an acoustic waveguide received within the tube, wherein the acoustic waveguide is operatively connected to the ultrasonic blade such that the acoustic waveguide is in acoustic communication with the ultrasonic blade, and (ii) a sheath positioned between the acoustic waveguide and the tube and configured to damp acoustic vibrations from the acoustic waveguide toward the tube;
• and (c) at least one sensor positioned on at least one of the end effector or the sheath, the method comprising:
• (a) measuring a force applied between the sheath and the acoustic waveguide as a measured force;
• and
• (b) providing real-time feedback of a non-clamping force applied against one of the ultrasonic blade or the clamp arm.

An ultrasonic surgical instrument, comprising:

• (a) an end effector including an ultrasonic blade;
• (b) a shaft assembly extending proximally from the end effector, wherein the shaft assembly includes:
• (i) a tube,
• (ii) an acoustic waveguide received within the tube, wherein the acoustic waveguide is operatively connected to the ultrasonic blade such that the acoustic waveguide is in acoustic communication with the ultrasonic blade, and
• (ii) a sheath positioned between the acoustic waveguide and the tube and configured to damp acoustic vibrations from the acoustic waveguide toward the tube;
• and
• (c) a sheath sensor positioned on the sheath and configured to measure force applied at the sheath as a measured force and thereby provide real-time feedback of a non-clamping force applied against the ultrasonic blade,
• wherein the sheath sensor is configured to measure the force applied between the sheath and the acoustic waveguide for determining the non-clamping force applied against the ultrasonic blade.