Efficiency enhancement of microparticles seeding density on the inner surface of polymer hollow microfibers using microfluidics

Lateral displacement of microparticles suspended in a viscoelastic fluid flowing through a microfluidic channel occurs due to an imbalance in the first (N1) and second (N2) normal stress differences. Here, we studied the lateral displacement of fluorescent microparticles suspended in a polyethylene glycol (PEG) solution in a two-phase flow with aqueous sodium alginate, flowing through a unique microfluidic device that manufactures microparticles seeded alginate-based hollow microfibers. Parameters such as concentration of the aqueous sodium alginate and flow rate ratios were optimized to enhance microparticle seeding density and minimize their loss to the collection bath. 4 % w/v aqueous sodium alginate was observed to confine the suspended microparticles within the hollow region of microfibers as compared to 2 % w/v. Moreover, the higher flow rate ratio of the core fluid, 250 L min-1 resulted in about 192 % increase in the microparticle seeding density as compared to its lower flow rate of 100 L min-1. The shear thinning index (m) was measured to be 0.91 for 2 % w/v and 0.75 for 4 % w/v sodium alginate solutions. These results help gain insights into understanding the microparticle displacement within a viscoelastic polymer solution flowing through a microfluidic channel and motivate further studies to investigate the cellular response with the optimized parameters.