Patent ID: 8906019

Claim:
A surgical instrument, comprising: a housing; an elongated shaft extending distally from the housing, the elongated shaft including a proximal portion defining a longitudinal axis, a distal portion, and at least one flexible portion supported between the proximal and distal portions to permit pivotal movement of the distal portion of the elongated shaft with respect to the longitudinal axis; an end effector supported by the distal portion of the elongated shaft, the end effector adapted for surgically treating tissue; and a locking mechanism operatively associated with the at least one flexible portion of the elongated shaft to selectively impede pivotal motion of the distal portion of the elongated shaft; the locking mechanism comprising: a fluid chamber defined within the flexible portion of the elongated shaft; a variable viscosity fluid disposed within the fluid chamber, the variable viscosity fluid configured to respond to an electromagnetic field such that the variable viscosity fluid exhibits an increased rigidity in the presence of the electromagnetic field and a reduced rigidity in the absence of the electromagnetic field; and an electrical coil coupled to a power source and extending at least partially through the flexible portion of the elongated shaft, the electrical coil arranged such that the electromagnetic field may be selectively induced by a delivery of electrical energy from the power source to the electrical coil.