Glass capillary microfluidics for production of monodispersed poly (dl-lactic acid) and polycaprolactone microparticles: Experiments and numerical simulations

[Display omitted] •Monodispersed biodegradable particles were made by three-dimensional flow focusing.•A good agreement was found between experiments and computational fluid dynamics.•Dripping regime prevailed at low Weber numbers and intermediate flow rate ratios.•Particle porosity was increased by incorporating water phase in the polymer solution.•A sustained release of lidocaine hydrochloride from inner water phase was achieved. Droplet size in microfluidic devices is affected by wettability of the microfluidic channels. Three-dimensional countercurrent flow focusing using assemblies of chemically inert glass capillaries is expected to minimize wetting of the channel walls by the organic solvent. Monodispersed polycaprolactone and poly(lactic acid) particles with a diameter of 18–150μm were produced by evaporation of solvent (dichloromethane or 1:2 mixture of chloroform and toluene) from oil-in-water or water-in-oil-in-water emulsions produced in three-dimensional flow focusing glass capillary devices. The drop generation behaviour was simulated numerically using the volume of fluid method. The numerical results showed good agreement with high-speed video recordings. Monodispersed droplets were produced in the dripping regime when the ratio of the continuous phase flow rate to dispersed phase flow rate was 5–20 and the Weber number of the dispersed phase was less than 0.01. The porosity of polycaprolactone particles increased from 8 to 62% when 30wt% of the water phase was incorporated in the organic phase prior to emulsification. The inner water phase was loaded with 0.156wt% lidocaine hydrochloride to achieve a sustained drug release. 26% of lidocaine was released after 1h and more than 93% of the drug was released after 130h.