A fluid infusion device and an insertion mechanism are disclosed. The insertion mechanism actuates an assembly having a fluid conduit and a needle. An embodiment of the insertion mechanism includes a first sliding block, a second sliding block, a torsion spring, and a living hinge. The first block is coupled to the conduit to move the conduit in an insertion direction. The second block is coupled to the needle to move the needle in the insertion direction and in a retraction direction, wherein movement of the second block in the insertion direction pushes the first block in the insertion direction. The living hinge is coupled between the torsion spring and the second block. Rotation of the torsion spring during an insertion action actuates the living hinge to move the second block in the insertion direction and, thereafter, in the retraction direction.
