Robots have steadily shrunk over decades, but building machines that can operate autonomously below one millimeter has remained a major challenge. At this scale, traditional movement and control mechanisms fail, and it has been nearly impossible to integrate power, sensing, computation, and propulsion into a single system. Researchers have now demonstrated microscopic robots that can independently sense, decide, and move within fluid environments for months at a time.

Research carried out by teams at the University of Pennsylvania (Philadelphia, PA, USA) and the University of Michigan (Ann Arbor, MI, USA) shows that the robots measuring roughly 200 by 300 by 50 micrometers, smaller than a grain of salt, are fully programmable and autonomous. Powered by light, they integrate propulsion, sensors, memory, and computing onto a single microscopic platform.

To overcome the limits of traditional mechanical movement, the researchers designed a propulsion system that uses electrically generated fields to push surrounding ions and water molecules, allowing the robots to “swim” without moving parts. Ultra-low-power electronics were developed to operate on just tens of nanowatts supplied by tiny solar panels. Custom computer architectures and compressed instruction sets enabled onboard processing and memory to fit within the remaining space.

The robots can move in complex patterns, coordinate in groups, sense temperature changes with high precision, and adjust their behavior in response. Embedded computers allow them to store programs, process sensor input, and encode information through patterned movements observable under a microscope. The work, described in Science Robotics and Proceedings of the National Academy of Sciences, represents the first demonstration of fully autonomous, programmable robots operating at this microscopic scale.

Because they operate at the scale of biological microorganisms, the robots could enable new approaches in medicine, such as monitoring the health of individual cells or sensing local tissue conditions. The platform is designed to be scalable and adaptable, allowing future versions to incorporate additional sensors, faster movement, and more complex programs.

“This is really just the first chapter,” said Assistant Professor Marc Miskin, PhD, senior author of the studies. “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.”

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