Controlled preparation of alginate microcapsules with multiphase oil cores using microfluidic chip

This work presents a feasible method for controllable preparation of monodisperse spherical alginate micro-capsules with structured multiphase oil cores, which have the potential to encapsulate multiple lipophilic actives that are not mutually soluble. Monodisperse (oil1 + oil2)-in-water ((O1 + O2)/W) droplets are generated using the assembled one-step co-flowing 3D-printed microfluidic chip. By cross-linking (O1 + O2)/W droplets with the calcium chloride collection solution, alginate microcapsules are obtained. It is noticed that the multiphase oil cores inside the microcapsules display self-adjustment behavior. The size and shell thickness of the alginate microcapsules, as well as the number of the cores inside the microcapsules, can be precisely tailored. Meanwhile, the factors that influence the sphericity of the microcapsules are investigated. Furthermore, we explore the impact of different types of the collection solutions on the final structure of the microcapsules. The proposed method shows excellent controllability in the design of alginate microcapsules with multiphase oil cores.