PMC

Planar (XY) mixing analysis in microplate bioreactor. (A) Comparison of planar mixing rates in wells driven by RBL posts (active mixing) versus diffusion alone (static RBL posts). Homogeneity was achieved in agitated wells in 2 min, versus 120 min in the wells mixed via diffusion alone. (B) Average relative mixing index (Outlined by Hashmi, 2014^[]) of the active mixing wells (3000, 6000, 9000 rpm) over time. Wells are considered fully mixed when they achieve an RMI of 0.85. At 3000 rpm, complete mixing was achieved after 180 s, whereas at 6000 rpm complete mixing was achieved after 215 s and at 9000 rpm complete mixing was achieved after 90 s

(a) Fluorescence micrograph of mixing chamber without magnetic particles. No mixing enhancement occurs and the mixing relies solely on diffusion. (b) Fluorescence micrograph of mixing chamber with non-rotating magnetic particles. Mixing is enhanced but not complete using this configuration. (c) Fluorescence micrograph of mixing chamber with rotating magnetic particles. Efficient mixing is observed using this configuration. These figures are adapted from [] with permission from the Royal Society of Chemistry. Copyright 2009 Royal Society of Chemistry. (d) Mixing enhancements observed over time when using magnetically actuated artificial cilia for three separate cilia trajectories. Adapted from [] with permission from the Royal Society of Chemistry. Copyright 2013 Royal Society of Chemistry.

Characterization of mixing performance of single vibrating sharp-tip at different flow rates and input voltages. (a) Thorough mixing at flow rate of 1.5 μL/min and input voltage of 1.07 V_pp; (b) Thorough mixing at flow rate of 1.5 μL/min and input voltage of 4.00 V_pp; (c) Incomplete mixing at flow rate of 30 μL/min and input voltage of 1.07 V_pp; (d) Complete mixing at flow rate of 30 μL/min and input voltage of 4.00 V_pp; Scale bars = 200 μm; (e) Mixing indexes at different positions along the microchannel from the starting point at the flow rate of 1.5 μL/min; (f) Mixing indexes at different positions along the microchannel from the starting point at the flow rate of 30 μL/min; (g) Relationship between mixing index and input voltage at a fixed flow rate (30 μL/min); (h) Relationship between the minimum required voltage for complete mixing and the flow rates.

Full lipid mixing phenotype correlates with contents mixing, and partial lipid mixing phenotype correlates with hemifusion. Representative images of double labeled RBC ghosts fusing with HA cells at pH 4.8 were taken after ∼4 min of lowering the pH. From the waiting time cumulants at pH 4.8, it was known that within ∼3 min, nearly all the possible lipid mixing events have initiated (see ) and cells showing full lipid mixing phenotype complete their dye redistribution within 50–75 s (see text for details). Looking at cells after longer times would not change the conclusion of this figure. Each box in the figure has an upper panel of images showing the double-labeled RBC for PKH26 and CF at the time of lowering the pH. The lower panel shows the respective dye redistribution (or lack of) at the end of the experiment. Clearly, cells having full lipid mixing phenotype (i.e., complete PKH26 redistribution) show contents mixing (i.e., CF redistribution) and cells having partial lipid mixing phenotype show no contents mixing. For all qualities of partial lipid mixing, no contents mixing is observed.