FIG. 1.
Inertial focusing and migration behaviors of particles with increasing fluid flow velocity (Uavg) in a curved low aspect ratio microchannel. (a) Particles injected from the inlet of the channel first abruptly equilibrate into two broad bands near the longer channel wall under the influence of shear lift (FS) and wall lift forces (FW) acting vertically with respect to the channel height. (i) At a relatively low flow velocity, particles migrate laterally towards the center equilibrium due to a rotation lift force (FR), forming two focusing streaks. (ii) As the flow velocity increase, the two streaks start to migrate towards the inner channel wall, followed by (iii) a single point focusing at a particular threshold due to the differential interplay between the net lift force (FL) and the Dean drag force (FD). (iv) Outer wall migration is induced as the flow velocity is increased above this threshold. (b) Top down view of fluorescent images illustrating the migration pattern of 10 μm diameter particle in a curved microchannel (200 μm 50 μm cross-section at 20 000 μm radius of curvature).