| abstract |
A sensor device (2) removably attachable to a drug delivery device (1), the sensor device comprising: a sensing arrangement (23) arranged within the sensor device; and circuitry (21) configured to process signals provided by the sensor arrangement, wherein the sensing arrangement is configured such that, when the sensor device is attached to the drug delivery device, the sensing arrangement is operable to read encoded information present on a rotatable component (15A) that is internal to the drug delivery device and that is able to be sensed through a window or aperture (63) of the drug delivery device, and is operable to sense through the window or aperture at least a part (68) of a drive mechanism of the drug delivery device, wherein the circuitry is configured: to determine, based on the encoded information, information relating to a set dose, and to determine, based on sensing of the part of the drive mechanism, information relating to whether the drug delivery device is in a dose setting mode or whether the device is in a dose delivery mode. |