Abstract: The displacement of refill valves in an implantable drug delivery device is reduced to permit the housings of a drug delivery device to remain compact in size while permitting reservoirs of increased depth to be used. In a preferred embodiment, a collapsible link is provided as a telescoping member incorporating a coil spring. As the valve is pulled into contact with its seat, a detectable pressure increase is sensed in the refill device. In accordance with the invention, as the drug supply contained in the reservoir depletes, the reservoir surface moves towards a collapsed position, compressing the coil spring and eventually contacting the valve stem, thereby lifting the valve from its seat. By virtue of telescoping link, the valve stem length and therefore the valve travel may be reduced as compared to prior art devices, thus eliminating the need for increased housing depth when deeper reservoirs are used. The collapsible link may be comprised of a second spring combined with a telescoping link.

Abstract: A peristaltic pumping mechanism is provided with a non-permeable peristaltic circuit comprising two strips of thin metal laser bonded at their edges to form a tube. In one embodiment, the non-permeable tubing takes the form of a continuous loop having input and output ports. In another embodiment, the tubing is open and generally U-shaped. In still another embodiment, a dual-tube circuit is provided, wherein a central, metal tube is disposed within an outer elastomeric tube having an inner diameter larger than the outer dimension of the metal tube. The elastomeric tube supports the metal tube only at the ends of the circuit, enabling the metal tube to “float” within the elastomeric tube.

Abstract: A peristaltic pump which may be used as an implantable medical device includes a rotor arm that is provided with a means for applying a regulated occluding force to the pump rollers. In a preferred embodiment, an expandable chamber containing a pressurized material may be incorporated into the pump. In this manner the pressure within the expandable chamber and thus the force applied to the pump roller may be kept constant despite local variations in the dimensions of the components and associated variations in the volume of the expandable chamber. Alternatively, the pressure within the expandable chamber may be modulated by the pressure of a reservoir communicating with the pump inlet or modulated by pump operating parameters such as motor torque.

Abstract: A peristaltic pump for an implantable medical device includes a pump tube defining an axis lying along a path in a first plane. Spherical rollers compress the tube at one or more points along the path in a direction non-parallel to the first plane, and preferably perpendicular to the first plane. Means for driving the rollers are provided so that liquid is moved through the tube.