Utilizing bifurcations to separate particles in spiral inertial microfluidics

Particles suspended in fluid flow through a closed duct can focus to specific stable locations the cross-section due hydrodynamic forces arising from inertia of disturbed fluid. Such particle focusing is exploited biomedical and industrial technologies separate particles by size. In curved ducts, result balance between two dominant on particle: (i) inertial lift small fluid, (ii) drag cross-sectional vortices induced centrifugal force Bifurcations equilibria take place as bend radius varies. By using mathematical model Harding, Stokes, Bertozzi [1], we illustrate via numerical simulations that these bifurcations be leveraged spiral achieve large separation different sized transiently smaller near saddle-points. We demonstrate this separating similar-sized particles, well have difference size, ducts with square cross-section. The formalism manipulate applied more broadly geometries microfluidics which may open new avenues techniques.