The invention provides for a sensor insertion assembly comprising a sensor cartridge (100, 302, 402, 600, 800, 900, 1000, 1100, 1200) comprising an insertion needle (106) and a sensor (108) within a sterile capsule(104, 604). The sensor insertion assembly further comprises an inserter (202) comprising a chamber (204) for receiving the sensor cartridge, wherein the inserter further comprises an insertion mechanism (700) operable for actuating the insertion needle for inserting the sensor into a subject. The sensor cartridge is removable from the chamber. The sensor cartridge is operable for shielding the insertion needle upon removal of the sensor cartridge from the chamber.