Dose detection system module for a medication delivery device

A dose delivery system, comprising:

• a medication delivery device having a dose actuator coupled to a device body, a reservoir containing a medication, and an end of the body configured to receive a needle, a sensed component rotatable during dose dispensing, wherein the dose actuator has a cylindrical button sidewall;
• and
• a dose detection module attachable to the dose actuator, the dose detection module having a housing, a plurality of attachment arms configured for coupling to the dose actuator, and an electronics assembly contained in the housing, comprising a processor, and at least one measurement sensor operably coupled to the processor, wherein the at least one measurement sensor is configured to detect angular position and/or rotational movement of the sensed component to generate position signals, wherein the electronics assembly includes an identification sensor operably coupled to the processor,
• wherein, when the dose detection module is attached to the dose actuator, a light guide member is disposed between the identification sensor and an axial surface of the dose actuator, the light guide member is configured to provide an optical path for the identification sensor.