Figure 2 Pressure characterization results for TFF, rTFF and HPTFF operation. Crossflow ramping in TFF and rTFF operation (A) and crossflow ramping with delta pressure control in HPTFF operation (B). Dashed lines represent the standard operating region of 1470 s-1 shear resulting in approximately 650 mL/min crossflow. Pressure measurements according to their position along the filter length are provided for TFF and the forward crossflow phase of rTFF (C), and for HPTFF (D), grey areas represent absolute fiber length. Pressure distributions at 650 mL/min crossflow versus time are shown for TFF and rTFF (E), where the forward crossflow phase corresponds to TFF operation, and rTFF is defined by alternation between forward and reverse crossflow. HPTFF pressure distribution versus time upon co-current filtrate flow activation was further measured at 650 mL/min crossflow (F).