Competition between Induced-Charge Electro-Osmosis and Electro-Thermal Effects around a Weakly-Polarizable Microchannel Corner

TL;DR

This study investigates the interplay between induced-charge electro-osmosis and electro-thermal effects near microchannel corners, revealing how buffer conductivity influences flow behavior through experiments and simulations.

Contribution

It provides a detailed analysis of how electro-thermal effects compete with ICEO flows at microchannel corners, highlighting the impact of buffer conductivity and frequency.

Findings

Electro-thermal effects increase with buffer conductivity.

Flow divergence from pure ICEO is due to Joule heating.

Experimental and numerical methods confirm flow behavior changes.

Abstract

The microchannel corner is a common inherent component of most planar microfluidic systems and thus its influence on the channel flow is of significant interest. Application of an alternating current electric field enables quantification of the non-linear induced-charge electro-osmosis (ICEO) ejection flow effect by isolating it from linear electro-osmotic background flow which is present under dc forcing. The hydrodynamic flow in the vicinity of a sharp channel corner is analyzed using experimental micro-particle-image-velocimetry (PIV) and numerical simulations for different buffer concentrations, frequencies and applied voltages. Divergence from the purely ICEO flow with increasing buffer conductivity is shown to be a result of increasing electro-thermal effects due to Joule heating.