Leiden University researchers 3D print brainless microrobots that navigate like living organisms
Flexible microswimmers sense and react to their environments through shape alone
Researchers at Leiden University have developed microscopic robots that swim, sense obstacles, and navigate complex environments without sensors, software, or external control. The behaviors derive entirely from the robots’ physical shape and their interaction with surrounding conditions.
Professor Daniela Kraft and postdoctoral researcher Mengshi Wei, both of the Leiden Institute of Physics (LION), designed the soft, chain-like microrobots from flexibly connected segments, and produced them using a Nanoscribe 3D microprinter.
Each structural element measures 5 micrometers, with bar-joints of 0.5 micrometers. The scale is what the researchers described as being at the technical limit of what 3D printing can currently achieve. For context, a human hair ranges from 70 to 100 micrometers in thickness.
“Animals like worms and snakes constantly adapt their shape as they move, which helps them to navigate their environments,” stated Kraft. “Macroscopic robots similarly use 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.”
When activated by an electric field, the chain structures began to swim at approximately 7 micrometers per second. The team observed a continuous loop in which the robots’ shape influenced their motion, and their motion in turn altered their shape to end up producing life-like responsiveness without any embedded electronics.
“We discovered there’s continuous feedback between the shape and motion of the robot: the shape influences how it moves, and its movements in turn alter its shape,” Kraft said. “This microrobot therefore senses how the environment changes its body and reacts to it, making it appear life-like. This means that we don’t need microscopic electronics for integrating smart abilities.”
Wei added: “When our microrobot encounters an obstacle, it automatically searches for another route. And when two robots meet, they naturally steer away from each other.”
Biomedical applications on the horizon
The researchers identified targeted drug delivery, minimally invasive procedures, and diagnostics as possible applications, and Kraft stated the immediate priority was deeper physical understanding.
“We now need to fully understand how such dynamic and functional behavior emerges. This knowledge will help us develop more advanced microrobots and devices, but also to better understand the physics of biological microswimmers and organisms.”
The work was published in Proceedings of the National Academy of Sciences (PNAS).
