Axisymmetric flow focusing of particles in a single microchannel.

Axisymmetric flow focusing of particles in a single microchannel has been proposed on the basis of the observation that a particle migrates toward the tube axis when it lags behind the fluid flow, which is supported by demonstrating that more than 90% of the particles are tightly focused within three times the particle diameter when negative electrophoretic mobility is imposed on the particles.