End-of-dose detection for drug delivery system

The system including a container configured to receive 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 positon 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 an 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 a non-expanded state when the needle is in the post-use positon.