Abstract: A portable platelet apheresis system can include: a whole blood inlet configured to receive whole blood; an anticoagulant source containing an anticoagulant; a mixer fluidly coupled with the whole blood inlet and anticoagulant source and configured to mix the whole blood and the anticoagulant; a whole blood sorter microfluidic network; a platelet poor outlet positioned to receive a platelet poor fraction; and a platelet concentrator outlet positioned to receive a concentrated platelet fraction. The whole blood sorter microfluidic network includes: a sorter constricted region having a first cross-sectional dimension; a sorter expansion region having a second cross-sectional dimension that is larger than the first cross-sectional dimension; at least one sorter side channel (platelet rich plasma channel) formed into a side of the sorter expansion region; and at least one sorter outlet (platelet poor plasma channel) that is downstream or medial from the at least one sorter side channel.