mbnu FY2019 Annual Report 3.1.2

Figure 2. Particle trapping induced by merging of different saline solutions at a T-junction. (a) Schematic of a symmetric T- junction with merging flows of solute concentrations c1 and c2. (b) A photograph of a glass microfluidic T-junction device made by selective laser-induced etching. (c) Image sequence of fluorescent colloidal particles (carboxylate-modified polystyrene latex, 1 μm in diameter) accumulating near the junction by merging of two colloidal suspensions with different solute concentrations (NaCl, c1 = 10 mM, c2 = 0.01 mM). Inlet mean flow speed is U = 0.34 mm/s. The channel has a square cross section with width w = 0.7 mm throughout the entire channel. (d) Particle trapping versus the inlet mean flow speed.