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.”