3D rotational diffusion microrheology using 2D video microscopy

TL;DR

This paper introduces a straightforward method to measure 3D rotational microrheology by analyzing 2D video microscopy projections of micrometric wires, enabling characterization of visco-elastic materials and object dimensions.

Contribution

It presents a novel approach to infer 3D rotational motion from 2D images, allowing for easier microrheological measurements of microscopic wires in fluids.

Findings

Successfully extracted rotational diffusion coefficients.

Measured wire diameter distribution consistent with electron microscopy.

Demonstrated potential for characterizing soft visco-elastic materials.

Abstract

We propose a simple way to perform three-dimensional (3D) rotational microrheology using two-dimensional (2D) video microscopy. The 3D rotational brownian motion of micrometric wires in a viscous fluid is deduced from their projection on the focal plane of an optical microscope objective. The rotational diffusion coefficient of the wires of length between 1-100 \mu m is extracted, as well as their diameter distribution in good agreement with electron microscopy measurements. This is a promising way to characterize soft visco-elastic materials, and probe the dimensions of anisotropic objects.