Non-uniform electro-osmotic flow drives fluid-structure instability

TL;DR

This paper investigates a fluid-structure instability caused by non-uniform electro-osmotic flow interacting with elastic walls, revealing a threshold-driven collapse relevant for soft electrokinetic device design.

Contribution

It combines experimental and theoretical analysis to identify the mechanism of electro-osmotic flow-induced instability in soft fluidic chambers, a novel insight in electrokinetic systems.

Findings

Electro-osmotic flow can induce negative gauge pressure leading to elastic wall collapse.

A threshold electric field exists beyond which instability occurs.

Multiple dynamic regimes of instability are identified.

Abstract

We demonstrate the existence of a fluid-structure instability arising from the interaction of electro-osmotic flow with an elastic substrate. Considering the case of flow within a soft fluidic chamber, we show that above a certain electric field threshold, negative gauge pressure induced by electro-osmotic flow causes the collapse of its elastic walls. We combine experiments and theoretical analysis to elucidate the underlying mechanism for instability and identify several distinct dynamic regimes. The understanding of this instability is important for the design of electrokinetic systems containing soft elements.