Formation of ring-shape microparticles with controlled shapes by manipulating the internal flow in microdroplets

Abstract

In the field of tissue engineering, a porous scaffold plays a crucial role in facilitating optimal nutrient and waste circulation during cell growth. This study proposes a fabrication method for microring particles with controlled shapes using a microfluidic system that precisely regulates the internal flow in microdroplets during the collection process. To determine the mechanism governing microring particle formation, a rotating collection system that applies centrifugal force while inhibiting the stirred flow of the collection phase was implemented. Consequently, the internal flow in microdroplets, until solvent evaporation, emerges as a critical factor in shaping microparticles. In this investigation, various experimental conditions, including stirring rate, temperature, and collection types, were systematically analyzed to elucidate the factors influencing the formation of microparticles. The generated porous particles were classified into five distinct types: porous, large-pore, ring, pocket-shaped, and dish-shaped particles. The morphology of these particles was observed using optical inverted microscope and field-emission scanning electron microscope(FE-SEM). To investigate their penetration properties based on shape, a comparative analysis was conducted by injecting solid, porous, and ring particles into a gradually narrowing microchannel. In addition, water was introduced at their respective stacked volumes within the microchannel to compare flow resistance according to their shapes. © 2024