Investigating the Response of Ferrofluid Droplets in a Uniform Rotating Magnetic Field: Towards Splitting and Merging

Ferrofluid droplets are of great importance due to their ability to be manipulated by magnetic actuation, enabling progress in various areas, such as nanotechnology, robotics, and optics. Moving, splitting, and merging the ferrofluid droplets need a comprehensive analysis of the behavior of the ferrofluid droplets in a magnetic field. Here, we analyze the response of ferrofluid droplets when they are under the effect of a uniform rotating magnetic field. A water-based ferrofluid droplet is immersed in a high-viscosity fluid, and the frequency of the applied field is changed from 0.01 to 0.30 Hz for performing experiments. Three distinct types of motion are observed during experiments: pure rotation at a low-frequency magnetic field, splitting the droplet at medium frequency field, and merging the small droplets into one droplet at high frequency. The responses of ferrofluid droplets are explained through the interaction of surface tension, drag, and magnetic force.