Separation and concentration of particles

A controlled incremental filtration (CIF) device configured for modulating a concentration of particles of desired size in a fluid in microfluidic flow, comprising:

• a substrate comprising at least one CIF module, the substrate defining in each CIF module:
• a central channel, the central channel extending along a flow path between a central channel flow input and a central channel flow output;
• a plurality of micro-features adjacent to the central channel, the plurality of micro-features defining a plurality of gaps, the plurality of micro-features separating the central channel from at least one side channel network, the plurality of gaps configured to fluidically couple the central channel to the at least one side channel network, the at least one side channel network extending along the central channel to at least one side channel output, the at least one side channel network comprising one or more of:
• a first side channel network portion comprising:
• a plurality of side channel curves adjacent to the central channel, at least a portion of the plurality of micro-features, and at least a portion of the plurality of gaps;
• the plurality of side channel curves being characterized by a plurality of lengths that decrease along the flow path, each side channel curve fluidically coupling at least one gap of the plurality of gaps in the first side channel network portion to one or more of:
• an adjacent gap in the plurality of gaps and an adjacent curve in the plurality of curves;
• and
• a second side channel network portion comprising:
• a side channel adjacent to the central channel, at least a portion of the plurality of micro-features, and at least a portion of the plurality of gaps;
• the side channel being characterized by a flow cross-section that increases along the flow path such that the plurality of gaps in the second side channel network portion are characterized by one or more of:
• a consistent flow fraction fgap and a plurality of different gap volumetric flow rates;
• the at least one side channel network being characterized by a decreasing flow resistance along at least a portion of the flow path effective to modulate a concentration of particles of a desired size in a fluid in microfluidic flow through said device.