Critical flux behavior of ultrathin membranes in protein-rich solutions

•Ultrathin silicon membranes have high critical flux in concentrated protein solutions.•Ultrathin silicon membranes operate at low transmembrane pressures at high flux.•Nanoparticle solutes captured in pores lower critical flux thresholds.•Ultrathin silicon membranes are ideal for microfluidic tangential flow filtration.•Micron-thick membranes perform poorly in microfluidic tangential flow filtration.