Patent ID: 7828764

Claim:
A system, the system comprising: a reservoir having an interior volume for holding an infusion medium, the reservoir having an inlet port for allowing the infusion medium to flow into the interior volume of the reservoir, and an outlet port for allowing the infusion medium to flow out of the interior of the reservoir; and a piston disposed at least partially within the reservoir, the piston being moveable within the reservoir, the piston comprising: a piston body for forcing the infusion medium out the outlet port of the reservoir, the piston body for receiving a plunger shaft, the piston body including an engagement portion for connecting to and disconnecting from the plunger shaft; and a piston septum pierceable by a transfer element to allow an infusion medium to be filled into the interior volume of the reservoir through the inlet port of the reservoir and through the piston body in a case where the engagement portion of the piston body is disconnected from the plunger shaft and the piston septum is pierced by the transfer element; wherein the inlet port through which the interior volume of the reservoir is filled with the infusion medium is different from the outlet port of the reservoir through which the infusion medium is forced out of the interior volume of the reservoir by the piston body.