Fluid pressure based end effector force transducer

A force transducer for use with a surgical instrument that includes a shaft and a gripper end effector at a distal end thereof, comprising:

• a jaw cap configured to snugly fit over a jaw of the gripper end effector;
• a collar configured to snugly fit about the shaft;
• a fluid filled sac including,
• a first fluid filled bladder disposed upon a jaw cap;
• a second fluid filled bladder disposed upon the collar;
• and
• a fluid filled tube providing fluid communication between the first and second fluid filled bladders.

A surgical instrument comprising:

• an elongated shaft including a proximal end and a distal end;
• an end effector located at the distal end of the shaft and including first and second jaws having opposing working faces and a pivot axis, wherein at least one of the first and second jaws is mounted to rotatably pivot about the pivot axis between an open position and a closed position;
• a transducer sac that includes,
• a jaw cap disposed about at least a portion of the first jaw that includes a first fluid filled bladder portion disposed over at least a portion of a working face of the first jaw;
• a collar disposed about the shaft that includes a second fluid filled bladder portion;
• a fluid filled tube portion integrally formed with the first and second bladder portions and providing fluid communication between the first and second fluid filled bladder portions;
• and
• a sensor operatively coupled to the second bladder portion to produce a sensor signal indicative of fluid pressure within the transducer sac.

A surgical instrument comprising:

• an elongated hollow shaft including a proximal end and a distal end;
• a pulley rotatably mounted at the distal end of the shaft for rotation about a pivot axis;
• a cantilever end effector extending from the pulley to rotate with the pulley about the pivot axis;
• a first wire extending within the shaft and engaging a first perimeter portion of the pulley and having a distal end secured to the end effector;
• a first actuator to provide the proximal direction force to the first wire;
• a first fluid filled sac including a first distal bladder portion positioned at a surface of the cantilever end effector to receive a force imparted by at least one of the first wire and a first wire anchor by contact with the at least one of the first wire and the first wire anchor, while the first actuator imparts the proximal direction force to the first wire;
• and
• a first sensor operatively coupled to produce a first sensor signal indicative of fluid pressure within the first fluid filled sac.

A method to determine magnitude of a force imparted to a working jaw surface of an end effector jaw disposed at a distal end of a surgical instrument shaft, comprising:

• imparting a reaction force to the end effector jaw to match the force imparted at the working jaw surface;
• converting the force imparted at the working jaw surface to an increased fluid pressure within a fluid filled sac;
• and
• converting the increased fluid pressure within a fluid filled sac to a sensor signal indicative of the increase fluid pressure.

A method to determine magnitude of a rotational force imparted to an end effector mounted for rotation about a pivot axis at the distal wrist portion of a surgical instrument shaft, comprising:

• imparting a reaction force to a cable coupled to provide a reaction rotational force at the distal wrist portion of the surgical instrument shaft, the reaction rotational force having a magnitude to match the rotational force imparted at the end effector,
• converting the reaction rotational force imparted at the distal wrist portion of the surgical instrument shaft to an increased fluid pressure within a fluid filled sac;
• and
• converting the increased fluid pressure within a fluid filled sac to a sensor signal indicative of the increase fluid pressure.