Patent ID: 7374565

Claim:
An implantable device, comprising: an enclosure; an accumulator comprising a cylindrical bellows contained within the enclosure and including a movable portion operably configured to vary an internal volume of the accumulator in relation to linear motion of the movable portion; a contact surface external to the accumulator and connected to the movable portion for bi-directional movement between a collapsed accumulator position and an expanded accumulator position, the contact surface comprising a brake drum externally aligned parallel to the linear motion of the movable portion; a braking member within the enclosure and proximally positioned and operably configured for movement between a braking contact position locking the movable portion to a present position at any selected position along a range of positions of the movable portion and a noncontact position with the contact surface allowing unimpeded linear movement of the movable portion, wherein the braking member comprises at least one brake caliper encompassing at least a portion of a circumference of the brake drum; and a brake actuator comprising a piezo-electric stack actuator operably configured to selectively position the braking member.