Brownian motion and the hydrodynamic friction tensor for colloidal particles of complex shape

TL;DR

This paper investigates how anisotropic colloidal particles move in a fluid, measuring their hydrodynamic friction tensors through experiments and confirming theoretical predictions for complex shapes.

Contribution

It introduces a method to experimentally determine the hydrodynamic friction tensor for colloids with complex shapes, revealing couplings between translation and rotation.

Findings

Hydrodynamic friction tensors measured for various anisotropic shapes.

Confirmation of theoretical calculations in low-Reynolds-number regime.

Identification of nontrivial translational-rotational couplings.

Abstract

We synthesize colloidal particles with various anisotropic shapes and track their orientationally resolved Brownian trajectories using confocal microscopy. An analysis of appropriate short-time correlation functions provides direct access to the hydrodynamic friction tensor of the particles revealing nontrivial couplings between the translational and rotational degrees of freedom. The results are consistent with calculations of the hydrodynamic friction tensor in the low-Reynolds-number regime for the experimentally determined particle shapes.