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Scientists are printed magnetic droplets



  magnetic field
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The inventors of the past centuries and scientists today are experiencing creative ways to make our lives better in magnets-from the magnetic needle to a compass on magnetic storage devices and even MRI (magnetic resonance imaging) machines scanned by the body.


All of these technologies rely on magnets made of solid materials. But what if you could make magnetic devices out of liquids? With a modified 3-D printer, a team of scientists at the Berkeley Lab has done so. Their findings, published July 1

9 in the journal Science can lead to a revolutionary type of printed liquid device for various applications from artificial cells that deliver target cancer therapists to flexible robots that can change "We have created a new material both fluid and magnetic. Nobody ever observed it before," says Tom Russell, a visiting expert scientist at the Berkeley Lab and professor of polymer science and engineering at the University of Massachusetts, Amherst who led the study. "It opens the door to a new science field in magnetic soft matter."

Jam sessions: making magnets from liquids

In the last seven years, Russell, Interfacial Assemblies Focused on Developing Liquids in Materials of Berkeley Lab Materials, dedicated to develop a new class of materials-3-D-printable all-natural structures.

One day, Russell arrived and was the first author of Xubo Liu's current study with the idea of ​​building fluid structures from ferrofluids, solutions of iron-oxide particles that became strong magnetic , but having another magnet. "We wonder if a ferrofluid can be temporarily magnetic, what can we do to make it permanently magnetic, and act like a solid magnet but still look and feel like a liquid?" Said Russell.

To find out, Russell and Liu-a graduated student researcher at the Berkeley Lab's Sciences Sciences Division and a doctoral student at the Beijing University of Chemical Technology – employed a 3-D-technique they developed the former Postdoctoral Researcher Joe Forth at the Berkeley Lab's Sciences Sciences Division to print 1 millimeter droplets from a ferrofluid solution containing iron-oxide-nanoparticles only 20 nanometers in diameter (the average size of an antibody protein.)

Using surface chemistry and sophisticated atomic force microscopy Molecular Foundry methods, authors Paul Ashby and Brett Helms of Berkeley Lab have declared that nanoparticles form solid -like shell in the interface between two liquids by a phenomenon called "interfacial traffic," causing nanoparticles to the crowd in the surface of the small pace, "like the walls that come together in a small room sitting on the people," Russell says.

To make th em magnetic, scientists put droplets through a magnetic coil into the solution. As expected, the magnetic coil pulls the iron-oxide nanoparticles towards it.

But when they removed the magnetic coil, something unexpected happened.

Video of three ferromagnetic liquid droplets containing iron oxide nanoparticle dispersions consisting of cylinders using a microfluidic device, and then locked in shape by the formation of magnetic nanoparticle surfactants in the interface.

The cylindrical droplets are placed in an oil with the same density, so they are fun, and then placed on a stirring plate with a rotating magnetic bar. Once magnetized, they act like floating solid magnets, rotating and dancing to one another.

A tiny drop of dye solution (Nile Red) is added to the oil to track the flow of the field around rotating ferromagnetic liquid droplets. ] The video was recorded from the top view and played in real time. The amount of ferromagnetic liquid droplets is 2μL, and the length of the ferromagnetic liquid cylinder is 2 mm. Credits: Xubo Liu and Tom Russell / Berkeley Lab

Like synchronized swimmers, droplets bend to one of the perfect unity, forming an elegant round. "Like tiny droplets dancing," Liu says.

In any case, these droplets have become permanent magnetic. "Almost we do not believe," Russell said. "Before our study, people have always been assumed that permanent magnets can only be made from solids."

Measure according to the measure, it is a magnet

All magnets, however large or small, a north pole and a south pole. With the measurement of magnetometry, scientists discovered that when they placed a magnetic field with a droplet, all the north-south polo poles of nanoparticles, from 70 billion iron-oxide nanoparticles floating around in the drops of 1 billion nanoparticles over the drops, responds simultaneously, like a solid magnet.

The key to this search is the iron-oxidative nanoparticles over the top of the drop. With just 8 nm between each of the billion nanoparticles, they together create a solid surface around each liquid droplet. In any case, when the dense nanoparticles on the surface are magnetized, they move this magnetic orientation into the particles that go through the core, and the whole drops are permanently magnetic, as solid, Russell and Liu explain.

found that the magnetic properties of the droplet were preserved, even though they divided a droplet into smaller, smaller droplets about the size of a human hair, Russell added.

Among the many amazing features of magnetic droplets, what stands out more, Russell The above is a change of shape to suit their surroundings, from one globe to one cylinder in a pancake , or a thin tube as an extremely hair, or even in the shape of an octopus-all without losing their magnetic properties.

Droplet & # 39; can also be tuned to switch between a magnetic mode and a nonmagnetic mode. And when their magnetic modes are open, their movements can be remotely controlled as taught by an outdoor magnet, Russell added.

Liu and Russell plan to continue research at the Berkeley Lab and other national labs to develop more complex 3-D print magnetic liquid structures, such as a liquid artificial cell, or miniature print liquid Robotics are expanding as a small propeller for those who are not targeted to deliver drug therapies to sick cells.

"What started as a usurious observation of the new science field," Liu says. "It's something that all young researchers dreamed about, and I'm fortunate to have the opportunity to work with a great group of scientists who are supported by Berkeley's world class facilities to become reality, "Liu says.


Nanocrystals of scientists in a liquid droplet in a solid-like state – and come back again


More info:
X. Liu el al., "Reconfigurable ferromagnetic liquid droplets," Science (2019). science.sciencemag.org/cgi/doi … 1126 / science.aaw8719

Provided by
Lawrence Berkeley National Laboratory

Citation :
New laws of attraction: Scientists printed magnetic droplets (2019, July 18)
retrieved July 18, 2019
from https://phys.org/news/2019-07-laws-scientists-magnetic-liquid-droplets.html

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