The microfluidic ratchet device consists of a single fluidic layer fabricated using soft-lithography of polydimethylsiloxane (PDMS) silicone. The mold for the microstructures consists of two photo-lithographically defined layers fabricated on a silicon wafer. The sorting region containing a matrix of funnels was fabricated using SU-8 3010 photoresist (MicroChem, Newton, MA, USA) producing features with thickness of 11–15 µm. The supporting microfluidic channels (SI, OSC1, OSC2, CFI and Outlets) were made from SU-8 3025 photoresist with a thickness of ~25 µm. The patterns for both masks were drawn using AutoCAD software.