Insider Brief
- Researchers supported primarily by the National Science Foundation have developed what they describe as the world’s smallest fully programmable autonomous robots, according to studies from the University of Pennsylvania and the University of Michigan.
- The microscopic, light-powered robots can sense their environment, execute programmed behaviors, and operate autonomously for months at a cost of about one cent each, combining ion-based propulsion from Penn with ultra-low-power computing developed at Michigan.
- Reported in Science Robotics and PNAS, the work addresses a decades-old challenge in microscale robotics and points to potential applications in cellular health monitoring, precision manufacturing, and coordinated robotic systems operating at biological scales.
Researchers backed primarily by the National Science Foundation have developed what they describe as the world’s smallest fully programmable autonomous robots, a development that could open new paths in medicine, manufacturing, and microscale engineering, according to studies from the University of Pennsylvania and the University of Michigan.
The robots — designed and fabricated at the University of Pennsylvania with computing systems developed at the University of Michigan — are microscopic swimming machines that can sense their environment, execute programmed behaviors, and operate autonomously for months at a cost of about one cent per unit, according to the universities. The work was reported in Science Robotics and the Proceedings of the National Academy of Sciences, with additional funding from the Air Force Office of Scientific Research, the Army Research Office, the Packard Foundation, the Sloan Foundation, Fujitsu Semiconductors, and internal support from the University of Pennsylvania.
Each robot measures roughly 0.2 by 0.3 by 0.05 millimeters, placing it at the scale of many microorganisms and making it barely visible to the naked eye. Despite their size, the robots can move in complex patterns, travel in coordinated groups, sense temperature changes with high precision, and adjust their behavior in response to local conditions, the researchers reported.
The advance addresses a long-standing bottleneck in robotics: autonomous motion at the microscale. While computing hardware has steadily shrunk for decades, independent movement has remained difficult for tiny machines because fluid drag and viscosity dominate at small scales. According to the research teams, this challenge has limited progress in microscale robotics for roughly 40 years.
“We’ve made autonomous robots 10,000 times smaller,” said Marc Miskin, assistant professor in electrical and systems engineering at Penn and senior author of the pair of studies.”That opens up an entirely new scale for programmable robots.”
The University of Pennsylvania team approached the problem by rethinking propulsion entirely. Instead of relying on moving parts, which are fragile and inefficient at small scales, the robots generate electric fields that interact with ions in surrounding water. Those ions, in turn, push nearby water molecules, producing motion. This mechanism allows the robots to swim without mechanical components, making them unusually durable and capable of operating for extended periods.
The University of Michigan contribution centered on ultra-low-power computing developed in the lab of David Blaauw and Dennis Sylvester. The robots’ onboard “brains” operate on approximately 75 nanowatts — about 100,000 times less power than a typical smartwatch. To achieve this, the researchers redesigned instruction sets so that tasks that would normally require multiple commands could be executed with a single instruction, allowing programs to fit into extremely limited memory.
“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.
Power and programming are delivered through light, researchers noted. Each robot is equipped with solar cells that supply energy and enable programming via light pulses, and each unit has a unique identifier that allows individualized instructions. This capability makes it possible to deploy groups of robots that perform different roles within a shared task.
In their current configuration, the robots are equipped with temperature sensors capable of detecting changes within about one-third of a degree Celsius. The researchers demonstrated that the machines could move toward warmer regions or communicate temperature information through distinctive motion patterns, suggesting potential applications in monitoring cellular activity or detecting localized changes in biological or chemical environments.
Beyond medicine, the teams point to potential uses in manufacturing, where fleets of microscopic robots could assist in assembling or maintaining microscale devices that are difficult or impossible to manipulate with conventional tools.
“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.”
Image credit: Kyle Skelil, University of Pennsylvania
