Patent ID: 8523889

Claim:
An ultrasonic surgical instrument, comprising: an end effector having a length extending along a longitudinal axis, the end effector configured to transmit ultrasonic vibrations along the length, and the end effector having a discontinuous acoustic impedance along the length, the end effector comprising: a first portion having a first specific acoustic impedance, the first portion disposed along the longitudinal axis and comprising a proximal end and a distal end; and a second portion having a second specific acoustic impedance different than the first specific acoustic impedance, the second portion disposed between the proximal end and the distal end of the first portion along the longitudinal axis to increase an active length of the end effector relative to an active length of an end effector without the second portion, wherein the active length is the distance from the distal end of the end effector where ultrasonic displacement is a predetermined level to a proximal location along the end effector where ultrasonic displacement has decreased below the predetermined level.