Microfluidic Spontaneous Emulsification for Generation of O/W Nanoemulsions-Opportunity for In-Space Manufacturing.

Abstract

The use of microfluidics for oil-in-water (O/W) nanoemulsification via spontaneous self-assembly is demonstrated. As this is known to be a longish process, both single- and multicontact microfluidic reactors are tested, the latter providing a longsome, constant microfluidic treatment to maintain advanced phase and interfacial mass transfer. Microfluidic devices provide strong advantages above conventional systems for spontaneous emulsification, with droplet sizes of 62 nm at desired surfactant-to-oil ratios (SOR) and a decrease of 90% in process time. Multicontact microfluidics have better performance than their single-contact counterparts, while critical aspects, e.g., process robustness, are also discussed. Ternary phase diagram analysis of the three components (oil, water, surfactant) allow to decide for the right mixing ratio and sequence of mixing steps for the nanoemulsions. Microfluidic spontaneous emulsification meets objective functions of the intended application to provide fortified beverages to astronauts in space exploration. In that viewpoint, an advantage is to achieve stable nanoemulsions at a level of concentrations much higher as compared to application (human intake), allowing a dilution factor to the final product of up to 100. This decreases notably the process time and allows for process flexibility, e.g., to dilute or tailor Earth-prepared nanoemulsion concentrate payloads in space.