Tiny Robot Weighs Just One Milligram and Uses Magnetic Fields to Walk

A team from the University of Maryland’s Department of Mechanical Engineering has designed perhaps the world’s smallest quadruped microrobot, measuring just 2.5mm x 1.6mm x 0.7mm and weighing in at one milligram. The microbot is loosely based on rotary-legged robots such as the University of Michigan’s RHex robot, as well as the gaits used by some tiny insects for locomotion, such as ‘pronking,’ trotting, bounding, and waddling.

Since the robot is too small to use conventional electronics and motors for movement, the engineers went with a magnetic approach by embedding magnets in its 3D-printed body and controlling them with an external magnetic field. A rotating magnetic field causes the tiny cubic magnets to rotate at speeds of up to 150Hz.

With all the magnets installed in the same orientation, it produces a pronking gait (leaping into the air with stiff legs); however others are possible by shifting the magnets around a bit in different orientations. Most impressively, the microbot has a top speed of 37.3mm/s and is quite durable as it was tested for 1 million actuation cycles with no wear or diminished performance.

As far as applications go, the engineers designed the robot to get an understanding of the dynamics of legged motion at a micro scale. This will ultimately lead to new designs and methods of control for autonomous robots at small scales. Considering the robot moves using magnetic actuation, I was hoping they could be used for something such as internal surgery, or maybe as a swarm platform for search and rescue in hazardous environments.