Singular point characterization in microscopic flows

TL;DR

This paper introduces an optical trap-based microrheology method to measure fluid fluxes around singular points, experimentally demonstrating its ability to distinguish flow singularities and assess their stability.

Contribution

It presents a novel optical trapping technique for characterizing singular points in microscopic fluid flows, including flow detection and stability analysis.

Findings

Successfully distinguished singular points from no-flow regions.

Demonstrated flow characterization around birefringent spinning spheres.

Validated the method's ability to assess flow stability.

Abstract

We suggest an approach to microrheology based on optical traps in order to measure fluid fluxes around singular points of fluid flows. We experimentally demonstrate this technique, applying it to the characterization of controlled flows produced by a set of birefringent spheres spinning due to the transfer of light angular momentum. Unlike the previous techniques, this method is able to distinguish between a singular point in a complex flow and the absence of flow at all; furthermore it permits us to characterize the stability of the singular point.