# Dynamic Sealing Using Magneto-Rheological Fluids

## TL;DR

This paper introduces a novel dynamic sealing technique for micropumps using magneto-rheological fluids, significantly reducing volumetric losses and enhancing efficiency and accuracy in microfluidic gear pumps.

## Contribution

It presents a new dynamic sealing method with theoretical and experimental validation, optimizing magnetic field conditions for improved micropump performance.

## Key findings

- Magneto-rheological fluids effectively reduce volumetric losses.
- Optimal magnetic field intensities improve sealing performance.
- The method enhances efficiency and accuracy of gear pumps.

## Abstract

Micropumps are microfluidic components which are widely used in applications such as chemical analysis, biological sensing and micro-robots. However, one obstacle in developing micropumps is the extremely low efficiency relative to their macro-scale counterparts. This paper presents a dynamic sealing method for external gear pumps to reduce the volumetric losses through the clearance between the tips of gears and the housing by using magneto-rheological (MR) fluids. By mitigating these losses, we are able to achieve high efficiency and high volumetric accuracy with current mechanical architectures and manufacturing tolerances. Static and dynamic sealing using MR fluids are investigated theoretically and experimentally. Two Mason numbers $Mn\left(p\right)$ and $Mn\left(\Omega\right)$ which are defined in terms of pressure gradient of the flow and velocity of the moving boundary respectively are used to characterize and evaluate the sealing performance. A range of magnetic field intensities is explored to determine optimal sealing effectiveness, where effectiveness is evaluated using the ratio of volumetric loss and friction factor. Finally, we quantify the effectiveness of this dynamic sealing method under different working conditions for gear pumps.