Compact positive displacement pump for wearable drug delivery device

A wearable drug delivery device, comprising:

• a reservoir configured to store a liquid drug, the reservoir comprising:
• a housing including an outer wall defining an interior chamber;
• a sealing member;
• and
• a slit through at least a portion of the housing, wherein the sealing member seals the slit;
• and
• a delivery pump device including a drive mechanism coupled to the reservoir for driving the liquid drug out of the reservoir, the drive mechanism comprising:
• a piston head disposed within the interior chamber of the housing;
• and
• a lead screw coupled to a drive nut, wherein the drive nut comprises a blade adjacent the piston head, wherein the blade is within the slit of the housing and configured to move within the slit to cut the sealing member, wherein an entirety of the slit and an entirety of the blade are contained within the reservoir, and wherein the lead screw has external threading engaged with corresponding internal threading of the drive nut, and wherein rotation of the lead screw causes the blade to move axially along the lead screw.

A method, comprising:

• providing a reservoir configured to store a liquid drug, the reservoir comprising:
• a housing including an outer wall defining an interior chamber;
• a sealing member;
• and
• a slit through the housing, wherein the sealing member seals the slit;
• coupling a drive mechanism of a delivery pump device to the reservoir, the drive mechanism comprising:
• a piston head disposed within the interior chamber of the housing;
• and
• a lead screw coupled to a drive nut, wherein the drive nut comprises a blade adjacent the piston head, and wherein the blade is within the slit of the housing and configured to move within the slit to cut the sealing member, wherein an entirety of the slit and an entirety of the blade are contained within the reservoir;
• and
• rotating the lead screw to cause the drive nut to move axially along the lead screw between a first position and a second position to force the liquid drug out of the reservoir.