The lift force on a spherical nanoparticle near a wall in micro/nanofluidics has not received sufficient attention so far. In this letter the concentration of phi 200 nm particles is measured at 0.25-2.0 mu m to a wall in a microchannel with pressure-driven de-ionized water flow (pressure gradient 0-2000 kPa/m). The measured data show the influence of the lift force on the nanoparticle concentration distribution. By introducing the Saffman lift force into the Nernst-Planck equation near a wall, we find that the lift force is dominant at the range of 2 < z(+) < 6 (z(+) = z/2r, r is the particle radius, z is the distance from the wall).

This paper was published as:

Zheng X, Silber-Li Z. The influence of Saffman lift force on nanoparticle concentration distribution near a wall. Applied Physics Letters,95(12):124105(2009)