Patent ID: 7762793

Claim:
A drive mechanism for an infusion device, the drive mechanism comprising: a first housing having an inlet, the first housing defining an interior volume for receiving fluidic media from the inlet, the interior volume having a width dimension; a coil arranged to be selectively energized; an armature moveable in the interior volume of the first housing at least between a retracted position and an advanced position in response to energizing the coil, the armature having a first pair of pole surfaces; a coil housing containing the coil, the coil housing composed of a magnetizable material and providing a second pair of pole surfaces in a magnetic flux path with the first pair of pole surfaces when the coil is energized; a second housing containing the coil housing, the second housing defining a piston channel extending through at least a portion of the second housing; a piston moveable along the piston channel in conjunction with movement of the armature at least between a retracted position and an advanced position to convey fluidic media from the interior volume of the first housing and out the piston channel in a case where the interior volume of the first housing contains fluidic media and the coil is energized to move the armature and the piston to the advanced position, the piston channel having a length dimension along which the piston moves between the retracted position and the advanced position; and a barrier member arranged between the armature and the coil housing, the barrier member defining an opening through which the piston extends into the piston channel, the opening having a width dimension that is less than the width dimension of the interior volume, the width dimension of the opening and the width dimension of the interior volume transverse the length dimension of the piston channel; wherein the armature comprises an armature body having a cavity and a magnetic material located within the cavity.