Nav: Home

Magnets for the second dimension

November 11, 2019

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to form two-dimensional shapes. The new building blocks, which the scientists call modules, are not dipolar but quadrupolar, which means they each have two north poles and two south poles. Inside each of the modules, which are 3D printed in plastic, there are two small conventional dipole magnets with their equal poles facing each other (see picture). The building blocks can be assembled like little chess boards to form any two-dimensional shapes. It works like this: Because the south and north poles attract each other, a quadrupole building block with its two south poles facing left and right will attract, on each of its four sides, a building block that is rotated by 90 degrees so its north poles on face left and right.

Building on this principle, the scientists made coloured modules with an edge length of just over two millimetres. They assembled them into pixel art emojis to demonstrate what the modules can do. However, possible use cases go way beyond such gimmicks. "We're particularly interested in applications in the field of soft robotics," says Hongri Gu, a doctoral student in Professor Bradley Nelson's group at ETH and lead author of the paper that the scientists recently published in Science Robotics.

Quadrupole and dipole in the same building block

The quadrupole dominates the magnetic properties of the modules. It is a little more complicated than that, though, because in addition to the strong quadrupole, the scientists also built a weak dipole into the building blocks. They achieved this by arranging the little magnets in the module at a slight angle to each other rather than parallel (see picture).

"This causes the modules to align themselves with an external magnetic field, like a compass needle does," Gu explains. "With a variable magnetic field, we can then move the shapes we have built out of the modules. Add in some flexible connectors and it's even possible to build robots that can be controlled by a magnetic field."

Gu says that their work was initially about developing the new principle. It is size-independent, he says, meaning that there is no reason why much smaller quadrupole modules couldn't be developed. The scientists are also studying how the modules could be used to combine a linear structure into a multidimensional object with the help of a magnetic field. This is something that could be of use in the medicine in the future: it is conceivable that objects such as stents could be formed from a thread consisting of such modules. The thread could be inserted into the body in a relatively simple, minimally invasive procedure through a tiny opening and then a magnetic field applied to assemble it into the final multidimensional structure inside the body.
-end-
Reference

Gu H, Boehler Q, Ahmed D, Nelson BJ: Magnetic quadrupole assemblies with arbitrary shapes and magnetizations, Science Robotics 2019, 4: eaax8977, doi: 10.1126/scirobotics.aax8977

ETH Zurich

Related Magnetic Field Articles:

Scholes finds novel magnetic field effect in diamagnetic molecules
The Princeton University Department of Chemistry publishes research this week proving that an applied magnetic field will interact with the electronic structure of weakly magnetic, or diamagnetic, molecules to induce a magnetic-field effect that, to their knowledge, has never before been documented.
Origins of Earth's magnetic field remain a mystery
The existence of a magnetic field beyond 3.5 billion years ago is still up for debate.
New research provides evidence of strong early magnetic field around Earth
New research from the University of Rochester provides evidence that the magnetic field that first formed around Earth was even stronger than scientists previously believed.
Massive photons in an artificial magnetic field
An international research collaboration from Poland, the UK and Russia has created a two-dimensional system -- a thin optical cavity filled with liquid crystal -- in which they trapped photons.
Adhesive which debonds in magnetic field could reduce landfill waste
Researchers at the University of Sussex have developed a glue which can unstick when placed in a magnetic field, meaning products otherwise destined for landfill, could now be dismantled and recycled at the end of their life.
Earth's last magnetic field reversal took far longer than once thought
Every several hundred thousand years or so, Earth's magnetic field dramatically shifts and reverses its polarity.
A new rare metals alloy can change shape in the magnetic field
Scientists developed multifunctional metal alloys that emit and absorb heat at the same time and change their size and volume under the influence of a magnetic field.
Physicists studied the influence of magnetic field on thin film structures
A team of scientists from Immanuel Kant Baltic Federal University together with their colleagues from Russia, Japan, and Australia studied the influence of inhomogeneity of magnetic field applied during the fabrication process of thin-film structures made from nickel-iron and iridium-manganese alloys, on their properties.
'Magnetic topological insulator' makes its own magnetic field
A team of U.S. and Korean physicists has found the first evidence of a two-dimensional material that can become a magnetic topological insulator even when it is not placed in a magnetic field.
Scientists develop a new way to remotely measure Earth's magnetic field
By zapping a layer of meteor residue in the atmosphere with ground-based lasers, scientists in the US, Canada and Europe get a new view of Earth's magnetic field.
More Magnetic Field News and Magnetic Field Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#566 Is Your Gut Leaking?
This week we're busting the human gut wide open with Dr. Alessio Fasano from the Center for Celiac Research and Treatment at Massachusetts General Hospital. Join host Anika Hazra for our discussion separating fact from fiction on the controversial topic of leaky gut syndrome. We cover everything from what causes a leaky gut to interpreting the results of a gut microbiome test! Related links: Center for Celiac Research and Treatment website and their YouTube channel
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.