The application relates a device and a method for receiving blood from a subject and processing the blood to form plasma or serum. The device comprises: an inlet (42) for introduction of blood from the subject into the device a separation membrane (50) in fluid communication with the inlet on a first side of the membrane, the separation membrane being capable of separating blood passing therethrough into a first portion that is enriched in plasma or serum, and a rejected portion concentrated in blood cells and a pre-packaged vacuum chamber (35) having a pressure less than ambient pressure prior to the point at which the device is used on the subject, the vacuum chamber being in gaseous communication with a second side of the membrane wherein the device comprises a first module and a second module removable from the first module, wherein the second module comprises a storage chamber for receiving the first portion of blood enriched in plasma or serum.
