US Patent 8038693 Methods for ultrasonic tissue sensing and feedback

An ultrasonic surgical instrument including an ultrasonic transmission member having a proximal end and a distal end is provided. The instrument also includes an ultrasonically-actuated cutting element having a tissue contacting surface and a clamp member supported adjacent to the cutting element for clamping tissue. The clamp member includes a sensing mechanism that senses load variations. A handle member located at the proximal end of the transmission member moves the clamp member relative to the cutting element. Also, a feedback mechanism is operatively coupled to the sensing mechanism that supplies information related to the load variations where the output of the tissue cutting element is adjusted based on the sensed load variations.