Fig. 2. Schematic representation of the dominant microfluidic platforms for preparing various lipid vesicles. Vesicles with diameters smaller than 100 nm are described as ‘small’ or ‘nano’, this includes small unilamellar vesicles (SUVs) and lipid nanoparticles (LNPs). Vesicles with diameters between 100 nm and 1 μm are described as ‘large’. Vesicles with diameters larger than 1 μm are described as ‘giant’, including giant unilamellar vesicles (GUVs), vesosomes (vesicle-in-vesicle), multilamellar vesicles (MLVs) and multicompartmental vesicles (MCVs). Microfluidic platforms represented by micromixers (reproduced from ref. 45 with permission from the American Society of Gene & Cell Therapy, copyright [2012]) and MHF (reproduced from ref. 15 with permission from Springer Nature, copyright [2016]) have demonstrated great potential in preparing lipid vesicles with nanoscale sizes for medical applications. Emulsion-based microfluidics focuses on preparing giant liposomal products as cell models or bioreactors from water-in-oil (W/O) emulsions. The pulsed jetting method (reproduced from ref. 46 with permission from the American Chemical Society, copyright [2007]) can prepare vesicles of ‘small’, ‘large’, and ‘giant’ sizes.