Microfluidic Fabrication of Monodisperse Hollow Microcapsules

This chapter introduces microfluidic strategies to controllably prepare monodisperse hollow microcapsules with microfluidic-generated double emulsions as templates. Using microfluidic devices, monodisperse water-in-oil-in-water (W/O/W) double emulsions are obtained and used as templates to fabricate monodisperse EC microcapsules. Most of the attempts to prepare alginate microcapsules using single emulsions as templates usually result in solid microspheres. The chapter shows the preparation of micron-sized monodisperse calcium alginate microcapsules by combining the microfluidic emulsification with internal gelation. Microfluidic technology with precise manipulation of emulsion droplets and high encapsulation efficiency has already shown great potential in the fabrication of monodisperse microcapsules for encapsulation and delivery. Based on microfluidics, the chapter then shows a simple emulsion-template approach for fabricating monodisperse hydrogel-based microcapsules with repeated glucose response under physiological temperature and glucose concentration conditions. It also introduces the microfluidic fabrication of multi-stimuli-responsive microcapsules with adjustable controlled-release by embedding temperature-responsive submicrospheres as "microvalves" into the magnetic- and pH-responsive microcapsule membrane.