The Attractions of the Magnetic Soft Matter Just Developed by Berkeley Lab Are Endless

Liquid robots and printable, cancer-fighting artificial cells may be in our near future thanks to new research that has generated magnetic soft matter for the first time.
Dana  Miller

So many of the simplicities of the engineering world that we have been enjoying for decades, and likely taking largely for granted, are based on magnet technology. Everything from electric motors to audio speakers to credit cards utilize solid-based magnets in order to function. A team of researchers at Berkeley Lab have just taken established ideas in magnet game to the next level by using a specialized 3D printer to generate a new substance, never before seen in science, which is both magnetic and liquid.

Wait, didn't liquid magnets exist before in the form of ferrofluids?

This new material is not to be confused with traditional ferrofluids, which are simply iron-oxide particles in solution form that become highly magnetized when in the presence of another magnet. Ferrofluids did, however, provide inspiration for the scholars seeking a way to make magnets both liqueform and printer-friendly.


Taking a cue from ferrofluid behavior, Tom Russell, a professor of polymer science and engineering at the University of Massachusetts, and this current study's author, Xubo Liu, a doctoral student at the Beijing University of Chemical Technology, have led the charge for the past seven years on the development of all-liquid structures that could be simultaneously 3D-printable.

Watch traditional ferrofluids in action in the video below.

So what's the science behind this?

With 3D printing technology helped along by former Berkeley Lab postdoctoral researcher Joe Forth, this team printed droplets of ferrofluid solution containing iron-oxide particles no bigger than an antibody protein (roughly 20 nanometers in diameter). 

Assisting scientists Brett Helms and Paul Ashby utilized atomic force microscopy and surface chemistry to observe that a phenomenon called "interfacial jamming" was taking place between the two liquids. Essentially this results in the nanoparticles crowding the surface of the droplet. Exposure to a magnetic coil predictably made the iron-oxide nanoparticles temporarily magnetic. 

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The magic happened when the magnetic coil was removed and the Berkeley Lab crew observed the droplets gravitating toward each other in a kind of synchronized, swirling dance. The magnetization of the droplets turned out to be permanent, and in subsequent standard magnetometry experiments, these new liquid magnets displayed unified north-south pole movement--just like solid magnets. 

The jammed iron-oxide nanoparticles observed at the droplet's surface somehow transfer the magnetization that they receive from the coil to the entire droplet. 

The coolest part is they are shape-shifters too

These magnetized droplets continued to amaze their discoverers by retaining their magnetic qualities no matter how small a division was made between them, or what shape they were forced to inhabit. Tentacled splat shapes to spheres to threads that resembled human hair all carried the same magnetic power as the original droplet.

The liquid magnets also appear to have the ability to be fine-tuned to toggle between a magnetic and non-magnetic mode. When switched into magnetic mode, their movements can be directed from an external magnet being operated remotely.

What can we do with this new magnetized liquid material?

The applications for liquescent magnets are numberless. Talks of propellered liquid robots used for cell therapy and surgeries of all kinds abound. Flexible robots that can change their shape to adapt to their environments, upgrades in MRI scans, and new fields of disease therapy can all be counted as future or current benefactors of this incredible breakthrough. In magnet science, opposites attract, and this exciting new liquid soft matter comes equipped with some very solid potential uses.

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