A microfluidic device for the study of the orientational dynamics of microrods

TL;DR

This paper presents a microfluidic device designed to observe and analyze the orientational tumbling behavior of microrods in shear flow, combining experimental observations with theoretical comparisons.

Contribution

The study introduces a novel microfluidic setup for real-time observation of microrod dynamics and compares empirical data with Jeffery's theoretical solutions.

Findings

Short time series fit Jeffery's equation

Observed orbit drift between solutions

Empirical trajectories show orbit drift

Abstract

We describe a microfluidic device for studying the orientational dynamics of microrods. The device enables us to experimentally investigate the tumbling of microrods immersed in the shear flow in a microfluidic channel with a depth of 400 mu and a width of 2.5 mm. The orientational dynamics was recorded using a 20 X microscopic objective and a CCD camera. The microrods were produced by shearing microdroplets of photocurable epoxy resin. We show different examples of empirically observed tumbling. On the one hand we find that short stretches of the experimentally determined time series are well described by fits to solutions of Jeffery's approximate equation of motion [Jeffery, Proc. R. Soc. London. 102 (1922), 161-179]. On the other hand we find that the empirically observed trajectories drift between different solutions of Jeffery's equation. We discuss possible causes of this orbit drift.