(334a) Magnetorheological Emulsions — Optimizing Magnetorheological Fluid Behavior with Emulsion Additives

Magnetorheological fluids (MRFs) are responsive materials whose viscosity and yield stress can be rapidly modulated by applying a magnetic field. This unique property enables their use in adaptive damping systems across industries such as automotive , prosthetics, and seismic vibration systems. However, one of the major limitations of MRF applications is the high power consumption required to generate and sustain magnetic fields, typically through electromagnetic coils. This energy demand restricts deployment in power-sensitive environments such as wearable technologies, battery-powered systems, or earthquake-responsive dampers, where energy efficiency, safety, and portability are critical. To address this challenge, we propose the use of magnetorheological emulsions (MREms), a novel subclass of MRFs incorporating emulsions as additives to modify fluid behavior and reduce power requirements.

In MREms, droplets of a stabilized secondary liquid phase are dispersed within the carrier fluid. Rheological testing shows that MREms maintain similarly low unpowered viscosities while achieving higher magnetized yield stresses compared to traditional MRFs, leading to improved yield stress at lower field strengths. This results in a stronger MR effect while requiring significantly less input current, effectively improving the power efficiency of the system. A custom-built in situ MR visualization platform (ISMR-VP) was developed to visualize particle interactions of MRFs and their additives in real time, revealing that emulsions facilitate an increase in yielding behavior with less magnetic input.

By tuning emulsion properties such as droplet size, dispersity, and viscosity, as well as magnetic particle concentration, MREms provide a scalable and customizable approach to minimize the energy demands of MR-based devices. These findings open a new path toward low-power, high-performance smart fluid systems capable of adaptive behavior without compromising efficiency.