A sensor device for attachment to an injection device

A supplementary device configured to be releasably attached to a drug delivery device, the supplementary device comprising:

• a first non-contact sensor configured to output signals indicative of a position of a first moveable component within the drug delivery device;
• and
• a processor configured to:
• receive the signals output from the first non-contact sensor;
• determine based on the signals a moment at which the drug delivery device changes from a pre-ejection state to a post-ejection state;
• in response to determining that the drug delivery device has changed from the pre-ejection state to the post ejection state, cause a display of the supplementary device to visually indicate that a user should hold the drug delivery device in its current position for a predetermined period of time.

A method of operating a supplementary device configured to be releasably attached to a drug delivery device, the method comprising:

• transmitting signals from a first non-contact sensor, wherein the signals indicate the position of a first moveable component within the drug delivery device;
• receiving the signals output from the first non-contact sensor using a processor of the supplementary device;
• determining based on the signals a moment at which the drug delivery device changes from a pre-ejection state to a post-ejection state;
• and
• causing, in response to determining that the drug delivery device has changed from the pre-ejection state to the post ejection state, a display of the supplementary device to visually indicate that a user should hold the drug delivery device in its current position for a predetermined period of time.

A system comprising:

• a drug delivery device;
• and
• a supplementary device comprising:
• a first non-contact sensor configured to output signals indicative of a position of a first moveable component within the drug delivery device;
• and
• a processor configured to:
• receive the signals from the first non-contact sensor;
• determine, based on the signals, a moment at which the drug delivery device changes from a pre-ejection state to a post-ejection state;
• and
• cause a display of the supplementary device to visually indicate that a user should hold the drug delivery device in its current position for a predetermined period of time to maintain a first orientation of the drug delivery device for a predetermined period of time, in response to determining that the drug delivery device has changed from the pre-ejection state to the post ejection state.