The present invention relates to a monitoring device (10) arranged to be operably connected to a medicament delivery device (12), said medicament delivery device (12) comprising a manually operated movable dose activating element (20), said monitoring device (10) comprising an electronic circuit (36), said electronic circuit (36) comprising a light emitting element (64) and a light sensor (66), wherein said light emitting element (64) and said light sensor (66) are positioned in relation to said dose activating element (20) so as to detect a manual operation of said dose activating element (20) from an initial position.本發明關於一種監視單元(10)，被配置用於可操作地連接至藥物輸送裝置(12)。該藥物輸送裝置(12)包含手動操作之可動的劑量啟動元件(20)。該監視單元(10)包含電子電路(36)，該電子電路(36)包括發光元件(64)和光感測器(66)。其中該發光元件(64)和該光感測器(66) 的位置係關於該劑量啟動元件(20)而設置，以偵測該劑量啟動元件(20)從初始位置的手動操作。
