The present invention relates to a cannula assembly (1) to be used with a separate trigger device (411-463) for triggering an activation mechanism (320-370) of the cannula assembly (1), said cannula assembly (1) comprising:a) a cannula module (100), comprising:- a skin-contacting surface (140) to be placed on an outer surface of an object or the skin of a body and- a cannula (120), configured to assume either a pre-operational state, in which the cannula (120) is retracted such that it does not project from the skin-contacting surface (140), or an operational state in which the cannula (120) projects from the skin-contacting surface (140)b) an inserter module (200), designed to be coupled to the cannula module (100) in the pre-operational state of the cannula (120) and to be separated from the cannula module (100) in the operational state of the cannula (120), and comprising:- an energy store (220), wherein the inserter module (200) is configured to move the cannula (120) from the pre-operational state to the operational state by at least partially discharging the energy store (220)- the activation mechanism (320-370), which can be triggered from outside the cannula assembly (1) by the trigger device (411-463) and is adapted to prevent the energy store (220) from being discharged before it is triggered by the trigger device (411-463), thus maintaining the pre-operational state of the cannula (120), and is adapted to enable the energy store (220) to be discharged after it is triggered by the trigger device (411-463), thus forcing the cannula (120) into the operational state.
