Leiden scientists 3D-print brainless microrobots that swim and navigate without electronics

Saturday 28 March 2026 - 11:50

By: Dakir Madiha

Leiden scientists 3D-print brainless microrobots that swim and navigate without electronics

Researchers at Leiden University have designed microscopic 3D-printed robots capable of swimming, navigating around obstacles and adapting to their surroundings, all without sensors, software or any electronic brain. The findings, published in the Proceedings of the National Academy of Sciences on March 26, mark a departure from conventional microrobotics, where machines typically rely on external control signals or onboard computing to function.

The microrobots, developed by physicist Daniela Kraft and postdoctoral researcher Mengshi Wei, are flexible chain-like structures made of loosely connected segments, each just 5 micrometers in diameter, far smaller than the width of a human hair. Printed in the laboratory using a Nanoscribe 3D microprinter, the chains begin moving when an electric field is applied, propelling themselves at roughly 7 micrometers per second.

What makes these robots unusual is that their behavior emerges entirely from their physical design and interaction with the environment. "We discovered that there is continuous feedback between the shape and movement of the robot: the shape influences how it moves, and its movements in turn change its shape," Kraft said in a university statement. "This means we do not need microscopic electronics to incorporate intelligent capabilities."

When slowed or stopped, the robots shake their tail while rear segments continue pushing forward. When they encounter an obstacle, they reorient automatically. When two robots meet, they move away from each other, all without any programmed instructions.

The inspiration came from biology. Animals such as worms and snakes constantly reshape their bodies as they move, and Kraft's team asked whether the same principle could work at microscopic scale. "Until now, microrobots were either small and rigid, or large and flexible," Kraft said.

The research opens possibilities for biomedical applications including targeted drug delivery and minimally invasive medical procedures. Unlike the autonomous microrobots announced earlier this year by the University of Pennsylvania, which use onboard computers and light-powered electronics, the Leiden robots achieve adaptive behavior through structure alone, with no computation required.

"We now need to fully understand how such dynamic and functional behavior emerges," Kraft said. "This knowledge will help us develop more advanced microrobots and devices, but also to better understand the physics of micro-swimmers and biological organisms."