Tiny 3D-Printed Robots Swim & Navigate Like Animals | TechXplore

Leiden, Netherlands – Researchers at Leiden University have created microscopic robots capable of swimming, sensing, navigating, and adapting to their environment without the need for a central nervous system, sensors, software, or external control. The robots, measuring just tens of micrometers in length – far smaller than the width of a human hair – represent a significant advancement in microrobotics and hold promise for biomedical applications.

The breakthrough, led by Professor Daniela Kraft and postdoctoral researcher Mengshi Wei at the Huygens-Kamerlingh Onnes Laboratory, is detailed in a recent publication in the journal Proceedings of the National Academy of Sciences. Their work demonstrates that complex behaviors can emerge from the shape and material properties of these tiny machines, rather than relying on traditional robotic components.

“Animals like worms and snakes constantly adapt their shape as they move, which helps them to navigate their environments,” explained Professor Kraft. “Macroscopic robots similarly apply flexibility for their function. However, until now, microrobots were either small and rigid, or large and flexible. We wondered if we could realize small and flexible microrobots in our lab.”

The robots are constructed as a flexible chain of self-propelling elements, 3D-printed using a Nanoscribe 3D-printer. Each element measures 5 µm in size, connected by bar-joints measuring 0.5 µm. When an electric field is applied, the chain begins to move, exhibiting a life-like swimming motion due to its inherent flexibility. The robots can achieve a speed of 7 µm/second.

“When the robot is slowed down or even stopped, it starts to wave its tail as if it wants to break free,” said Mengshi Wei. “This happens because the elements in the back still want to move, and they can do so because of their flexibility.”

Researchers discovered a continuous feedback loop between the robot’s shape and its movement. The shape influences how it moves, and the movements, in turn, alter its shape. This interaction allows the microrobot to sense changes in its environment and react accordingly, without the need for traditional sensors. “Which means that we don’t need microscopic electronics for integrating smart abilities,” Kraft added.

The robots also demonstrate autonomous navigation capabilities. Wei noted that when encountering an obstacle, the microrobot automatically searches for an alternate route. When two robots meet, they naturally steer away from each other. They can even move in dense environments and displace obstacles in their path.

The development of these autonomous microrobots opens up possibilities for targeted drug delivery, minimally invasive medical procedures, and advanced diagnostics. Kraft stated that future research will focus on fully understanding how these dynamic and functional behaviors emerge, with the goal of developing even more advanced microrobots and gaining insights into the physics of biological microswimmers and organisms.