An electrosurgical instrument includes a housing, a shaft coupled to the housing, and an end-effector assembly disposed at a distal end of the shaft. The end-effector assembly includes first and second jaw members, at least one of which is movable from a first position wherein the jaw members are disposed in spaced relation relative to one another to at least a second position closer to one another wherein the jaw members cooperate to grasp tissue therebetween. The second jaw member includes an electrically-conductive tissue-engaging surface and a protruding element extending therefrom. The protruding element is configured as an elongated strip extending along a length of the second jaw member. The electrosurgical instrument also includes a vibration coupler and an oscillation mechanism configured to generate mechanical vibration in the vibration coupler. The vibration coupler includes a distal end movably coupled to a proximal end of the second jaw member.
