Controlled production of monodisperse polycaprolactone microspheres using flow-focusing microfluidic device

These days, biodegradable microsphere polymers have been attracting increasing interest as a cosmetic injectable filler. Particularly, polycaprolactone (PCL) microspheres are well known for their safety and long degradation time. However, these microspheres are usually produced by the conventional stirring method, which has an inherent drawback related to the size control of the microspheres; accurate size control is critical for the use of these microspheres as a filler. Here, we demonstrate the fabrication of monodisperse PCL microspheres in the size range of 26.6-161 μm using a flow-focusing microfluidic device. The acquired coefficient of variation of the solidified microspheres is approximately 4.5%; thus, these microspheres meet the requirement of being monodisperse. The study results show the feasibility of manufacturing PCL microspheres using a microfluidic device, and these microspheres have better morphological characteristics, thereby reducing pain and infection after their injection into the skin. Furthermore, the specific target size of the solidified microspheres is met. Therefore, undesired outcomes after microsphere injection through the dermis, such as phagocytosis and inflammatory reactions, are less likely to occur.