Passive separation of whole blood

A method for compression sedimentation, comprising:

• providing a flexible reservoir comprising a liquid mixture, the liquid mixture comprising two or more particulate distributions, the two or more particulate distributions characterized by one or more of:
• different effective average particulate diameters and different densities;
• and
• passively sedimenting the liquid mixture in the flexible reservoir to form a supernatant and a subnatant, the passively sedimenting comprising using a flat substrate, the flat substrate being perpendicular to gravity within about ±10 degrees,
• the supernatant comprising at least a first particulate distribution characterized by one or more of a first effective average particulate diameter and a first particulate density;
• and
• the subnatant comprising at least a second particulate distribution characterized by one or more of a second effective average particulate diameter and a second particulate density.

A method for separation of whole blood (WB), comprising:

• providing a flexible reservoir comprising the WB;
• pressurizing the flexible reservoir comprising one or more of the WB, the supernatant comprising the PRP and the subnatant comprising the RBCs to a pressure;
• and
• sedimenting the WB in the flexible reservoir for a period of time to form a supernatant comprising a platelet rich plasma (PRP) and a subnatant comprising red blood cells (RBCs) the sedimenting comprising using a flat substrate, the flat substrate being perpendicular to gravity within about ±10 degrees;
• using the pressure to direct one or more of the supernatant comprising the PRP and the subnatant comprising the RBCs to a secondary separation process, thereby separating the WB.