Hydrodynamic mobility of an optically trapped colloidal particle near fluid-fluid interfaces.
Using optical tweezers, we measure the anisotropic hydrodynamic mobility of a colloidal particle by tracking its thermal motion in an optical trap located near fluid-fluid interfaces, namely, liquid-vapor and liquid-liquid interfaces. The method requires no controlled fluid flow, is independent of conservative interactions between particle and interface, and resolves distance dependent friction to within a fraction of the particle radius. Near the liquid-vapor interface, the friction decreases below that in the bulk, corresponding to predictions of a "perfect-slip" surface.
Wang
G M
GM
Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia.
Prabhakar
R
R
Sevick
E M
EM