# A Tunable Electrorheological Fluid Microfluidic Rectifier: Irreversibility of Viscous Flow due to Spatial Asymmetry Induced Memory Effects

## TL;DR

This paper demonstrates a microfluidic rectifier using electrorheological fluid and spatial asymmetry, achieving tunable flow rectification by exploiting memory effects induced by electric fields, which break flow reversibility.

## Contribution

It introduces a novel fluidic rectifier that combines geometric asymmetry with electric field-induced memory effects to achieve tunable, irreversible flow without moving parts.

## Key findings

- Achieves over tenfold flow rectification
- Demonstrates rapid electric field tuning of flow
- Shows potential for fluidic diodes and ratchets

## Abstract

Due to the reversibility of viscous flow it is not expected to obtain a fluidic rectifier simply from geometrical asymmetry without any moving mechanical parts. Here, we found a counter example by using spatial asymmetry combined with electric field to inject memory effects that render the flow irreversible. This stems from the strong dependency of the electrorheological (ER) fluid particle chaining on the flow direction. A funnel-shaped microfluidic rectifier with ER fluid has been shown to be easily and rapidly tuned via the applied electric field to achieve more than an order of magnitude rectification along with pressure oscillations. These findings are of importance for realization of fluidic diodes, rectifiers and ratchets.

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Source: https://tomesphere.com/paper/1908.02363