Emulsion Electrocoalescence in microfluidics: impact of local electric fields

TL;DR

This study investigates how local electric fields influence droplet coalescence in microfluidic systems, revealing the roles of oil resistance and formulation in controlling electrocoalescence onset.

Contribution

It provides a quantitative analysis of electrocoalescence mechanisms in microfluidics, highlighting the impact of electrical resistance and droplet configuration on coalescence behavior.

Findings

Electrical resistance of oil controls electrocoalescence onset

Local electric field enhancement depends on formulation and droplet number

Insights enable better control of droplet coalescence in microfluidic applications

Abstract

The mechanism of coalescence of aqueous droplet pairs under an electric field is quantitatively studied using microfluidics in quiescent conditions. We experimentally trap droplet pairs and apply electric fields with varying frequencies and formulation compositions. We find that the electrical resistance of the oil used as continuous phase controls the onset of electrocoalescence in quiescent conditions. We observe that the local field enhancement between droplets strongly depends on formulations but also on the number of droplets across the electrodes. These findings provide a better understanding of the onset of electrocoalescence and pave a route towards the rationalization of droplet-based microfluidics operations.