Scientists created the world’s smallest fully functional microrobot

Two insect-like robots developed at Washington State University, a mini-bug and a splash, are the smallest, lightest and fastest fully functional microrobots ever built.

Such miniature robots could one day be used to work in fields such as artificial pollination, search and rescue, environmental monitoring, microfabrication or robotic surgery. According to the article in the Proceedings of the IEEE Robotics and Automation Society International Conference on Intelligent Robots and Systems, the mini bug weighs eight milligrams and the water rover weighs 55 milligrams. Both can move at a speed of about six millimeters per second.

A breakthrough in speed and miniaturization

“Although this is fast compared to other microrobots of this scale, it lags behind its biological cousins,” said Conor Trygstad, a graduate student in the School of Mechanical Engineering and Materials Science and lead author of the paper. Usually an ant weighs up to five milligrams and can move at a speed of almost one meter per second.

The key to tiny robots is the tiny actuators that move the robots. Trygstad used a new manufacturing technique to shrink the actuator down to the smallest milligram size ever made.

“The actuators are the smallest and fastest ever developed for microrobotics,” said Nestor O. Perez-Arancibia, a Flaherty professor of engineering in WSU’s School of Mechanical and Materials Engineering who led the project.

Advanced driver technology

The actuator uses a material called shape memory alloy, which can change its shape when heated. It has been called “shape memory” because it remembers and then returns to its original shape. Unlike a typical motor that moves a robot, these alloys have no moving parts or rotating components.

“Mechanically, they are very solid,” Tryugstad said. “The development of an ultralight actuator opens up new areas of microrobotics.”

Shape memory alloys are not generally used for large-scale robotic movements because they are too slow. However, in the WSU robots, the actuators are made of two 1/1000 inch diameter shape memory alloy wires. With small amounts of current, the wires can be easily heated and cooled, allowing the robots to flap their wings or move their legs at speeds of up to 40 times per second. In previous tests, the actuator could lift 150 times its own weight.

Compared to other technologies used to move robots, SMA technology requires very little electricity or heat to move them.

Future directions and improvements

“The SMA system requires much less complex systems to power them,” Trygstad said.

Tryugstad, an avid fly fisherman, has long been observing waders and wanted to study their movements more deeply. While the WSU aquatic robot uses a plain flapping motion to move, the natural bug makes more efficient paddle legs, which is one of the reasons the real thing can move much faster.

Researchers want to clone another insect and develop a water-traveling robot that can move both above and below the surface of the water. They are also working on using small batteries or catalytic combustion to make their robots fully autonomous and independent of a power source.