Three-dimensional tracking of particle migration in viscoelastic fluids via oscillatory microfluidics

We present an experimental microfluidic platform capable of reconstructing full three-dimensional trajectories of single particles in viscoelastic fluids by exploiting oscillatory flow. The system combines synchronized high-speed imaging from orthogonal perspectives with a custom-fabricated square microchannel and optical correction techniques, enabling high-resolution, time-resolved observation of particle dynamics. The device is applied to study the migration of spherical particles in Polyethylene Oxide solutions, providing the first complete measurements of particle trajectories in such flows. The effects of initial particle position, flow rate, oscillation period, and fluid rheology are systematically analyzed.