Novo Nordisk A/S
DRUG DELIVERY DEVICE WITH MEANS FOR DETERMINING EXPELLED DOSE

Abstract:

The present invention provides a drug delivery device (1) of the type in which a piston rod (10, 110) extends along a reference axis and is forced to rotate in an expelling direction about the reference axis during a dose expelling event to cause an expelling of drug from a drug reservoir (30, 130), and a resilient ratchet element (12) is operatively coupled with the piston rod (10, 110) and undergoes a deflecting motion comprising elastic deformation and recovery in response to an expelling of a predetermined dose increment, which deflecting motion occasions a velocity fluctuation of the piston rod (10, 110), comprising: a rotator module (50, 150) operatively coupled with the piston rod (10, 110) and configured to rotate about the reference axis against a rotation resisting force in response to a rotation of the piston rod (10, 110) in the expelling direction, the rotator module (50, 150) comprising a sensor system (70, 71; 170, 183; 270, 183) for monitoring a torque transferred by the piston rod (10, 110) during the dose expelling event, wherein the sensor system (70, 71; 170, 183; 270, 183) is configured to, from the monitored torque, identify occurrences of velocity fluctuation of the piston rod (10, 110) attributable to the deflecting motion of the resilient ratchet element 15 (12).