Experimental Study of Particle-Liquid Flow Behaviour in a Microchannel Attached to an Inlet Reservoir

An experimental study of a solid particle-liquid mixture in a microchannel was conducted by injecting a particle-liquid mixture into a 3.0 mm diameter cylindrical reservoir connected to a square microchannel. Glass particles with diameters ranging from 8 to 12 μm and density between 0.95 and 1.15g/ml, as well as polystyrene particles with diameters ranging from 8 to 50μm and an average density of 1.03–1.05 g/ml were mixed with de-ionized water to create particle-liquid mixtures. The mixture could be continuously stirred in the reservoir using a small magnetic stir bar. The number of particles entering the microchannel was found to depend on the concentration and density of the particles in the reservoir, stirring and fluid flow rates. The particles with a density larger than the carrier fluid entered the microchannel, settled at the bottom of the channel and became immobile at low fluid flow rates, blocking the subsequent particle flow. In many cases, the particles flowed in small groups or clusters, which were separated by short distances. The average distance between the particles or particle clusters was found to vary both with the stirring rate in the reservoir as well as the fluid flow rate in the microchannel.