The world’s smallest fully programmable, autonomous robots have been unveiled at the University of Pennsylvania, featuring a brain developed at the University of Michigan. These microscopic swimming machines, measuring just 0.2 by 0.3 by 0.05 millimeters, can independently sense and respond to their surroundings, operate for months, and cost merely a penny each.
These groundbreaking robots, barely visible to the naked eye, are capable of moving in complex patterns, sensing local temperatures, and adjusting their paths accordingly. Developed with primary support from the National Science Foundation, these light-powered robots hold potential for significant advancements in medicine and manufacturing, such as monitoring the health of individual cells and aiding in the construction of microscale devices.
Revolutionizing Microscale Robotics
“We’ve made autonomous robots 10,000 times smaller,” stated Marc Miskin, assistant professor in electrical and systems engineering at Penn and senior author of studies published in Science Robotics and the Proceedings of the National Academy of Sciences. “That opens up an entirely new scale for programmable robots.”
The robots can move in complex patterns and even travel in coordinated groups, much like a school of fish. Their propulsion system, devoid of moving parts, ensures durability, enabling them to be easily transferred with a micropipette and capable of swimming for extended periods.
Innovative Propulsion and Computing
For decades, electronics have shrunk in size, highlighted by the sub-millimeter computers developed in the lab of David Blaauw and Dennis Sylvester, professors of electrical and computer engineering at U-M. However, robots have struggled to keep pace, primarily due to the challenge of independent motion at the microscale—a hurdle that Miskin believes has stalled the field for 40 years, until now.
“We saw that Penn Engineering’s propulsion system and our tiny computers were just made for each other,” said Blaauw, a senior author of the Science Robotics study. Operating at the microscale in water, where drag and viscosity are significant, Miskin’s team designed a propulsion system that moves the water rather than the robot itself. By generating an electrical field that nudges ions in the surrounding liquid, these ions then push on nearby water molecules, creating the force needed to move the robot. This mechanism is detailed in PNAS.
“To run the robot’s program on 75 nanowatts of power, which is 100,000 times less than a smartwatch requires, we had to rethink the computer program instructions,” Blaauw explained. “We condensed what would conventionally require many instructions for propulsion control into a single, special instruction.”
Potential Applications and Future Developments
These robots are both powered and programmed by light pulses, with each having a unique identifier for individualized programming. This capability could enable a team of robots to each take on different parts of a group task. The batch of robots described in Science Robotics is equipped with sensors that detect temperature to within a third of a degree Celsius, allowing them to monitor cellular activity by moving toward areas of increasing temperature or reporting temperature changes.
Future versions of these robots could store more complex programs, move faster, integrate new sensors, or operate in more challenging environments. “This is really just the first chapter,” Miskin said. “We’ve shown that you can put a brain, a sensor, and a motor into something almost too small to see, and have it survive and work for months. Once you have that foundation, you can layer on all kinds of intelligence and functionality. It opens the door to a whole new future for robotics at the microscale.”
Collaborative Efforts and Support
This pioneering project received additional support from the University of Pennsylvania Office of the President, Air Force Office of Scientific Research, Army Research Office, Packard Foundation, Sloan Foundation, and Fujitsu Semiconductors. Maya Lassiter, a Ph.D. student in electrical and systems engineering at Penn, and Jungho Lee, a Ph.D. student in electrical and computer engineering at U-M, are co-first-authors. Other contributors include Kyle Skelil, Lucas Hanson, Scott Shrager, William Reinhardt, Tarunyaa Sivakumar, and Mark Yim of Penn, alongside Sylvester and Li Xu of U-M.
As the field of microscale robotics continues to evolve, the implications of these tiny yet powerful machines are vast, offering a glimpse into a future where robotics can seamlessly integrate into the minutiae of biological and industrial processes.
