Liquid to liquid biological particle fractionation and concentration

A device for fractionation and concentration of particles from a fluid sample, the device comprising:

• a cartridge containing an inlet port and an outlet port and having alternating layers of plastic spacers and filters positioned serially between the inlet port and outlet port, wherein the inlet port, filters, and outlet port are positioned along a longitudinal axis, the longitudinal axis being perpendicular to the filters, each of the filters having a porous surface with all pores on a given filter being of a constant size, wherein the filters are arranged in series of decreasing pore size for capture of particles from a fluid sample, the alternating layers of plastic spacers and filters creating a plurality of internal volume chambers adjacent each porous surface, wherein the cartridge is adapted to direct a fluid sample flow in a substantially unidirectional manner along the longitudinal axis in each chamber, into the inlet port, perpendicularly through the decreasing pore size filters, and out of the outlet port, in a single pass, such that all of the fluid sample that entered into the inlet port passes through the outlet port while the particles are retained at a given filter according to particle size and do not pass to a subsequent filter if they are larger than the pore size of the given filter;
• a permeate pressure source in fluid communication with the cartridge;
• and
• a foam injection port at each end of the plurality of internal volume chambers and a retentate port at each opposite end of the plurality of internal volume chambers;
• wherein the particles are eluted tangentially from said each porous surface by foam injected by the foam injecting port and collected through the retentate port, and dispensed in a reduced fluid volume.