Investigation on drop dynamics during formation and hardening process of a microcapsule

This research investigates the micro-encapsulation process with a pressure-type micro-atomizer. Alginate and CaCl₂ aqueous solution are used as the membrane material and hardening agent, respectively. The high speed images were taken to investigate the formation processes of the microcapsules. Results show that the geometric shape of the microcapsules was sensitive to the droplet flying distance and the concentration of alginate aqueous, but insensitive to the concentration of CaCl₂ aqueous. Results also show that the membrane thickness of the microcapsules was controlled by the diffusion processes of calcium chloride. An empirical formula was derived to describe the rate change of the membrane thickness in the hardening processes.