A high-precision study of hindered diffusion near a wall

Prerna Sharma, Shankar Ghosh, and S. Bhattacharya

A high-precision study of hindered diffusion of a sphere due to its proximity to a solid interface was performed using an optical tweezer combined with digital holography microscopy and a phase-sensitive detection technique. The study provides a confirmation, with high accuracy and no adjustable parameters, of Faxen’s law which describes the variation of the diffusivity of a sphere as a function of its distance from the wall in a Newtonian liquid due to hydrodynamic effects. This general technique is useful for application in microfluidics and lubrication of small devices with moving parts.

DOI