We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid ($1–100\mu \mathrm{m}{\mathrm{s}}^{-1}$) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions ($0.001\mathrm{Pa}\mathrm{s}<\eta <0.090\mathrm{Pa}\mathrm{s}$). We find that the force is accurately described by Reynolds lubrication theory with a no-slip boundary condition, even at maximum strain rates of up to $250000{\mathrm{s}}^{-1}$. Compared to earlier studies of hydrodynamic forces on small particles, we reduce the uncertainty in the absolute particle-plate separation by using an evanescent-wave measurement of the separation.

• Received 21 July 2006

DOI:https://doi.org/10.1103/PhysRevLett.98.028305