A biological fluid collection device that includes a housing and a cartridge that is removably receivable within a portion of the housing is disclosed. The biological fluid collection device of the present disclosure allows for collection of capillary blood from a finger stick and provides a closed system that reduces the exposure of a blood sample. In one embodiment, a cartridge of the present disclosure also provides fast mixing of a blood sample with a sample stabilizer. In another embodiment, a cartridge of the present disclosure provides automatic plasma separation of the blood sample. Advantageously, once the cartridge is filled with a sample and removed from the housing, the cartridge can be used for a variety of important purposes.
