Synopsis: Magnetic Carpet Ride

Magnetic particles self-assemble into a sheet that can carry cells and other tiny cargo to a specific location.
Synopsis figure
F. Martinez-Pedrero and P. Tierno, Phys. Rev. Applied (2015)

The targeted delivery of medicines and the assembly of microscopic machines require reliable ways of delivering small particles to a precise location. Researchers at the University of Barcelona, Spain, devised a method to transport cells and other small objects on a magnetic “carpet,” which can be steered through a liquid with an external magnetic field. The carpet is made of small magnetic particles that self-assemble into a flat sheet, and it may be useful for transporting delicate cargo that are easily damaged by the electric fields or chemicals used in other techniques.

To make the carpets, Fernando Martinez-Pedrero and Pietro Tierno started with 3-micrometer-diameter plastic beads containing iron oxide, a material that polarizes easily in a magnetic field. They suspended the beads in a liquid layer between two glass slides, which they positioned between magnetic coils that provided fields along two axes in the slide and in the vertical direction. When the authors applied a rotating magnetic field in the plane of the slide, each bead developed a dipole that attracted nearby beads. These forces made the beads organize into a flat sheet. Applying an additional oscillating field along the vertical direction caused the beads to rotate within the sheet, pushing the carpet gently forward through the liquid.

Like a joystick, the three magnetic fields control the motion of the carpets. In one demonstration, the authors scooped a yeast cell onto a carpet and carried it 90 micrometers away—a distance about twice the carpet’s diameter. In another experiment, the carpet passed an obstacle by cleaving and then reforming.

This research is published in Physical Review Applied.

–Jessica Thomas


Features

More Features »

Subject Areas

MagnetismBiological Physics

Previous Synopsis

Atomic and Molecular Physics

Quantum Microscope Images Fermionic Atoms

Read More »

Next Synopsis

Quantum Information

Heralded Qubit Transfer

Read More »

Related Articles

Viewpoint: A Toy Model for Active Interfaces
Biological Physics

Viewpoint: A Toy Model for Active Interfaces

A new statistical model predicts the evolving shape of a cellular membrane by accounting for the active feedback between the membrane and attached proteins. Read More »

Viewpoint: Watching a Quantum Magnet Grow in Ultracold Atoms
Magnetism

Viewpoint: Watching a Quantum Magnet Grow in Ultracold Atoms

Two experiments watch an antiferromagnetic phase of matter emerge in ultracold Rydberg atoms, opening up a new platform for quantum simulation. Read More »

Viewpoint: The Dance of Water Molecules around Proteins
Biological Physics

Viewpoint: The Dance of Water Molecules around Proteins

A combination of experiments, simulations, and modeling has revealed the anomalous diffusion of water molecules along the surfaces of proteins. Read More »

More Articles