Viscoelastic Particle Train Formation in Microfluidic Flows Using a Xanthan Gum Aqueous Solution

Viscoelastic polymer solutions have been widely employed as suspending liquids for a myriad of microfluidic applications including particle and cell focusing, sorting, encapsulation. It has recently shown that viscoelastic can drive the formation equally spaced particles called “particle trains” result viscoelasticity-mediated hydrodynamic interactions between adjacent particles. Despite their potential impact on such droplet encapsulation flow cytometry, only limited experimental studies ordering are currently available. In this work, we demonstrate shear-thinning aqueous xanthan gum solution drives self-assembly trains centerline serpentine device with nearly circular cross section. After flowing change mutual distance organize in aligned structures characterized by preferential spacing, quantified terms distributions interparticle distance. We observe occurrence multi-particle strings, mainly doublets triplets, interrupt continuity train. To account fluctuations number window, introduce concept local concentration, observing an increase concentration leads to triplets. also using single tube connect sample results drastic reduction doublets/triplets, thus leading more uniform Our findings establish foundation optimized deterministic cytometry.