A method of separating a plurality of particles (14) from a portion of fluid, comprising directing the plurality of particles (14) into a microchannel (12). A first portion (16) of particles (14) is focused into an equilibrium position in the microchannel (12). The focused first portion (16) is directed into a first outlet (18) aligned with the equilibrium position. A portion of the fluid is directed into one or more outlets (20, 22). A microfluidic device (10) for separating a plurality of particles (14) from a portion of fluid, comprising a microchannel (12) having a first aspect ratio and a length L, thereby focusing the particles (14) directed therein into an equilibrium position in the microchannel, wherein at least a first portion (16) of the particles (14) focuses at distance X from a beginning of the microchannel (12). A first outlet (18) disposed after distance X and aligned with the equilibrium position to receive at least the first portion (16) of the particles (14) after the first portion (16) focuses into an equilibrium position in the microchannel (12). At least a second outlet (20) for receiving a second portion of the particles (14) before the second portion focuses into an equilibrium position.