Robots are changing assembly lines. They’re capable of building everything from cars to future Google hardware.

At Brigham and Women’s Hospital and Carnegie Mellon University, researchers are looking at robotic assembly on the micro scale. A recent paper in Nature Communications (subscription required) documents tiny robots capable of working with basic chips and living cells.

The robot, which is less than a millimeter long, is just a simple rectangle that contains metal particles. Magnets surrounding the building area pull it in any directions with enough power that the robot can push different blocks of material into place.

The researchers were able to use the robot to assemble 1mm square pieces of gel cut into different shapes, including squares, circles and triangles. But it is also capable of moving more complex shapes like spheres and rods. By sliding up a tiny ramp, the robot can stack objects to build taller…