At some point in our lives, we have all tried connecting a pair of magnets using the same side poles, only to discover they repel one another. The same can be said with cubed magnets, try putting them next to each other, and they will arrange themselves in a column. The reason this happens is that those magnets are dipolar, and can only align themselves using opposite poles (north/south).
Researchers at ETH Zurich have designed magnetic cubes that defy that north/south relationship and can be connected to form any number of 2D shapes regardless of their orientation. Rather than being dipolar, the new building blocks are quadrupolar, meaning they have two north poles and two south poles. The scientists call these new blocks quadrupole modules, with each housing two small dipole magnets with their equal poles facing each other housed in a 3D-printed enclosure.
The quadrupole modules can be assembled to form chessboard-like two-dimensional shapes. The team explains, “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 it's north poles on face left and right.”
Although the modules offer a robust magnetic quadrupole, the team also included a weak dipole in the modules as well, which are arranged at a slight angle to each other. The arrangement causes the blocks to align themselves when an external magnetic field is introduced. By varying that field, the researchers can manipulate the cubes to form various shapes.
While making different emoji’s is an excellent example of what can be done with quadrupole modules, the scientists are looking to utilize them in soft robotics by adding flexible connectors, which could be used in the medical field to create stents that are put in place using magnetic fields.