World’s Smallest Autonomous Microrobots Redefine the Limits of Robotics
Scientists at the University of Pennsylvania have unveiled what they describe as the world’s smallest fully programmable, autonomous microrobots, marking a major breakthrough in robotics at the microbial scale. Barely visible to the naked eye, these microscopic machines can sense their surroundings, make decisions, and operate independently for months, pushing autonomy into dimensions previously thought impractical.
Each robot measures approximately 0.2 by 0.3 by 0.05 millimeters, placing it at the scale of bacteria and single-celled organisms. Despite their size, the robots can swim through fluid environments, respond to temperature changes, and even coordinate movement in groups, mimicking behaviors seen in biological systems.
Researchers say the achievement represents a long-awaited convergence of motion, sensing, and computation at extreme miniaturization.
“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 research. “That opens up an entirely new scale for programmable robots.”
Operating at microscopic scales introduces unique challenges. Water behaves less like a fluid and more like thick syrup, making conventional propulsion systems ineffective. Instead of propellers or joints, the microrobots move by manipulating the surrounding liquid itself.
Rather than pushing against water, the robots generate an electric field that nudges ions in the fluid. Those ions then push nearby water molecules, creating thrust that moves the robot forward. Because this propulsion method contains no moving parts, the robots can function for months without mechanical wear and can be transferred easily using a micropipette.
This design also allows the robots to move collectively, coordinating their motion in groups similar to schools of fish.
The robots’ intelligence comes from ultra-miniaturized computers developed at the University of Michigan. These processors run on just 75 nanowatts of power, roughly 100,000 times less than a smartwatch, enabling sustained operation at microscopic scales.
“We saw that Penn Engineering’s propulsion system and our tiny computers were just made for each other,” said David Blaauw, a senior author of the study.
To make autonomy possible at this scale, researchers had to rethink how software instructions work. “We had to totally rethink the computer program instructions, condensing what conventionally would require many instructions for propulsion control into a single, special instruction,” Blaauw explained.
Most of each robot’s surface is covered with solar cells that harvest light for power and double as optical receivers. Light pulses both energize the robots and program them, while unique identifiers allow individual units to receive customized instructions.
The current generation includes temperature sensors capable of detecting changes within one-third of a degree Celsius. Robots can move toward warmer areas or signal temperature shifts by wiggling, a behavior researchers compare to the honeybee “waggle dance.”
Each microrobot costs roughly one cent to produce, operates without moving parts, and can survive for extended periods in fluid environments. Researchers say this combination of affordability, durability, and autonomy could unlock transformative applications.
“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.”
Future versions could carry additional sensors, store more complex programs, or function in harsher conditions. Scientists believe the technology could eventually enable targeted drug delivery, microscale manufacturing, environmental sensing, and minimally invasive medical procedures.
As published in Science Robotics, the research signals a pivotal moment for microrobotics, demonstrating that true autonomy is now possible at scales once reserved for living cells