Lipid films were prepared by first melting the required amount in a glass vial at 60 °C. The resultant lipid film was dissolved in dry ethanol (Sigma Aldrich) by sonication at 37 kHz for 30 minutes (XUBA-3 model, Grant Instruments, Cambridge SG8 6GB, UK) to 14 mM. This was filtered using a syringe filter (0.45 µm pore size; polyether sulfone) into a new vial that had been blown thoroughly with a nitrogen stream for ~3 seconds. For tocopherol acetate compositions, slightly elevated temperatures were needed for adequate dissolution. Separately, the aqueous phase was prepared by dissolving Pluronic F-127 in 1 x PBS (pH 7.4) at a concentration such that lipid:polymer ratios were maintained at 10:1. Solutions like these were prepared on the day of MHF experiments. Both solutions were taken up by plastic Normject syringes and affixed to a syringe pump (Fusion Touch 100, KR Analytical). The MHF chip was firstly charged with dry ethanol, then affixed to a clear acrylic sheet with BlueTac and placed into a microscope holder (Nikon TE 2000; 4x objective). via microfluidic tubing (PTFE, 0.8 ID x 1.8 mm OD) to their respective inlets. A piece of tubing (~10 cm) was fitted to the outlet of the MHF chip and fed into a 7 ml glass collection vial. The syringe pump corresponding to the lipid in ethanol solution was set to 100 µL/min and left until there was evidence of flow, as viewed through LabView software. The aqueous stream was introduced by setting the flow rate of the other syringe pump to 100 µL/min. Both streams were allowed to equilibrate (~1-2 min) before steadily focusing the central channel by adjusting each flow rate in 20 µL/min increments. When altering flow rate ratios (FRR), the buffer stream containing the triblock polymer was diluted via a T-junction connected to a separate syringe containing 1 x PBS. Total flow rates were never increased above 480 µL/min.