Needle insertion-retraction system having dual torsion spring system

An insertion/retraction mechanism for a drug delivery device, the insertion/retraction mechanism comprising:

• a retraction hub comprising an inside surface, a first primary rotational stop extending radially inwardly from the inside surface, and a second primary rotational stop extending radially inwardly from the inside surface;
• an insertion hub disposed inside of the retraction hub comprising a shaft having an outside surface, a first complementary rotational stop extending radially outwardly from the outside surface, and a second complementary rotational stop extending radially outwardly from the outside surface, the insertion hub further comprising a spindle connected to the shaft, the spindle having a needle pathway;
• an insertion/retraction mechanism housing that houses the retraction hub and the insertion hub in a rotatable manner and comprises a needle exit aperture;
• a flexible needle configured to extend through the needle pathway of the spindle of the insertion hub and to selectively pass through the needle exit aperture of the insertion/retraction mechanism housing during insertion and retraction of the flexible needle;
• a dual torsion spring system, the dual torsion spring system, including a right wound torsion spring and a left wound torsion spring, operably connected to the retraction hub, the insertion hub, and the insertion/retraction mechanism housing;
• and
• an activation trigger operably connected to the dual torsion spring system;
• wherein, in an initial position, the first primary rotational stop engages the first complementary rotational stop, the retraction hub is in a first rotational position relative to the insertion/retraction mechanism housing, and the flexible needle does not pass through the needle exit aperture,
• wherein, in an inserted position, the second primary rotational stop engages the second complementary rotational stop as a result of the insertion hub being rotated relative to the retraction hub by a first spring bias provided by the dual torsion spring system, the retraction hub is in the first rotational position relative to the insertion/retraction mechanism housing, and the flexible needle passes through the needle exit aperture, and
• wherein, in a retracted position, the second primary rotational stop engages the second complementary rotational stop, the retraction hub is in a second rotational position relative to the insertion/retraction mechanism housing as a result of the retraction hub being rotated relative to the insertion/retraction mechanism housing by a second spring bias provided by the dual torsion spring system, and the flexible needle does not pass through the needle exit aperture.

A method of deploying a needle of an insertion/retraction mechanism from a drug delivery device, the method comprising:

• in an initial position, in which a flexible needle of the insertion/retraction mechanism is contained within an insertion/retraction mechanism housing, engaging a first primary rotational stop of a retraction hub with a first complementary rotational stop of an insertion hub and placing the retraction hub in a first rotational position relative to the insertion/retraction mechanism housing;
• triggering an activation trigger operably connected to a dual torsion spring system to cause one of a right wound torsion spring and a left wound torsion spring of the dual torsion spring system to rotate the insertion hub relative to the retraction hub to achieve an inserted position where a second primary rotational stop of the retraction hub engages a second complementary rotational stop of the insertion hub, the retraction hub is in the first rotational position relative to the insertion/retraction mechanism housing, and the flexible needle extends outside the insertion/retraction mechanism housing;
• triggering the activation trigger operably connected to the dual torsion spring system to cause the other of the right wound torsion spring and the left wound torsion spring of the dual torsion spring system to rotate the retraction hub relative to the insertion/retraction mechanism housing to achieve a retracted position in which the second primary rotational stop of the retraction hub engages the second complementary rotational stop of the insertion hub, the retraction hub is in a second rotational position relative to the insertion/retraction mechanism housing, and the flexible needle is contained within the insertion/retraction mechanism housing.