Fig. 7. Microfluidic refinements for hydration. a| Schematic representations of the design of Y. Lin et al. Two 4 mm diameter wells were formed by bonding 2 mm thick PDMS to glass. The two cavities were connected by a channel. One cavity was for lipid film accommodation and hydration buffer injection to produce liposomes, and the other was for pumping out buffer. Reproduced from ref. 134 with permission from Elsevier, copyright [2006]. b| Schematic drawing of the micro-tube system designed by H. Suzuki et al. Lipid chloroform solution was first injected to the 50 mm position of the microtubes with the same total length of 1.5 mm and various diameters of 200, 320 and 530 μm. After the lipid film formed by desiccator drying, PBS was pumped in and washed the microtubes, and the effluent was collected. Reproduced from ref. 135 with permission from the Society of Chemical Engineers, Japan, copyright [2008]. c| Schematic illustration of K. Kitazoe et al.'s touch-and-go lipid wrapping technique. This technique constructed multifunctional envelope-type gene delivery nanodevices (MENDs) in two steps: (i) lipid coating in the microfluidic device and (ii) MEND formation in the microfluidic device. The top panel illustrates the mechanism of MEND formation based on the electrostatic interaction: the positively charged condensed plasmid DNA touched the lipid films on the glass, the substrate was wrapped in the lipid bilayer, and released as the MENDs. Reproduced from ref. 136 with permission from the Royal Society of Chemistry, copyright [2011].