For the duration of the experiment, repeated slough/re-growth cycles in the PPF-1 strain were observed, as indicated by the continuous variations in the biofilm OD. Temporary increases in CV correlated with sloughing events indicating an increase in heterogeneity, likely due to a roughening of the exposed biofilm surface. After sloughing, the residual biofilm was largely contained in the microchannel corners where the applied shear stress was lower, and the larger local surface provided a higher density of anchor points. Following sloughing of the PPF-1 strain, regrowth occurred from the residual biofilm segments in the corners, causing a narrowing of the effective channel width and increases to the shear stress, as observed in other biofilm studies in low-aspect-ratio microchannels. In the case of the PAO1 strain, a two-stage sloughing event followed the maximum biofilm accumulation at 72 hours, and a less significant sloughing event occurred at 100 h. It appeared that sloughing was less frequent for PAO1 than for PPF-1. Additionally, in contrast to PPF-1, sloughing played almost no role in modifying the heterogeneity of PAO1 (Figure ), indicating removal along a fracture boundary that resulted in no appreciable restructuring of the remaining biofilm. With temporary exceptions during and immediately following sloughing of the PPF-1 biofilm, the CVs of both biofilms generally tended toward lower values (more homogeneous) with time, but the PPF-1 strain was more heterogeneous than PAO1 throughout the experiment. Even after 140 hours, the CV of the PPF-1 was nearly twice that of the PAO1. Heterogeneous biofilm topographies are generally associated with higher exposed surface area, which is known to increase biofilm growth rates due to enhancements in nutrient loading. Because biofilms are known to present weaker mechanical properties (e.g., lower viscosity and Young's modulus) during fast-growth stages and to possess different cohesivity in the top versus base layers, it appears that the growth-slough cycles may produce a feedback loop that maintains the biofilm in a state that is conductive to pseudo-continuous production of ejecta into the flow stream.