End-of-dose detection for drug delivery system

A drug delivery system for injecting a medicament, the system comprising:

• a container configured to deliver a medicament;
• a drive assembly which, upon actuation, is configured to expel the medicament from the container;
• a needle for injecting the medicament to a patient;
• a needle actuator assembly comprising a movable portion biased by a biasing member and configured to move the needle between a pre-use position, a use position for delivery of the medicament to the patient, and a post-use position after delivery of the medicament is completed;
• and
• a tube in fluid communication with the container and the needle, the tube comprising a radially expandable portion having an expanded state and a non-expanded state, wherein the expandable portion is configured to be in the expanded state upon actuation of the drive assembly and in the non-expanded state when the needle is in the post-use position,
• wherein the moveable portion of the needle actuator assembly engages the expandable portion of the tube when the expandable portion of the tube is in the expanded state, thereby preventing movement of the needle actuator assembly.