Related Experiment Video
Updated: Jul 4, 2026

Aqueous Droplets Used as Enzymatic Microreactors and Their Electromagnetic Actuation
Published on: August 28, 2017
Magnetic Janus droplets as soft robots
Boris Kichatov1, Vladimir Sudakov1, Dariya Kalyuzhnaya2
1Semenov Federal Research Central for Chemical Physics, Moscow 119991, Russia.
Hypothesis:
Emulsion Janus droplets containing magnetic nanoparticles can be used as soft magnetic robots. If the densities of the immiscible liquids comprising the Janus droplets differ significantly, the Janus droplets acquire a non-spherical shape in a gravitational field. Due to the anisotropic structure, such droplets may possess unique properties necessary for creating "smart liquids."
Experiments:
VDL 100 oil and fluocarbon oil Fluorinert FC-40, whose densities differ significantly, are used to create non-spherical magnetic Janus droplets. The VDL 100 oil contains paramagnetic nanoparticles Fe3O4. Using a microfluidic chip, an emulsion oil/oil//water containing spherical monodisperse droplets was obtained. When exposed to a gravitational and magnetic field for several days, the spherical droplets transform into non-spherical quasi-stable Janus droplets.
Findings:
Due to the difference in density between hydrocarbon oil and fluocarbon oil, spherical binary emulsion droplets in a gravity field, under the influence of the buoyancy force, acquire a dumbbell-shaped form. Under the combined action of a gravity and magnetic field, the droplets acquire a barrel-shaped form. Such droplets can be used as soft robots for carrying loads and for mixing liquids in microreactors. Emulsions with barrel-shaped droplets can be used to create "smart liquids" whose light transmittance can be varied using a magnetic field.
Related Concept Videos
Magnetic Force
The magnetic force acting on a moving charge...
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
Magnetic Vector Potential
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...
Magnetic Flux
Suppose a surface is divided into elements of area dA. For each element, the component of the magnetic field that is normal to the...
Potential Due to a Magnetized Object
The vector...
Atomic Force Microscopy
The AFM Probe
The probe is regarded as the heart of any AFM setup and comprises the...

