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Overview of the microrobot circuits. (A), A mm-scale chip of roughly 100 microrobots, resting on a gloved fingertip. Each microrobot contains several integrated pieces of microelectronics, spanning sensing, memory, processing, communication, and power (scale bar: 200 μm). These devices were fabricated together in a 55 nm CMOS process at a commercial foundry and were optimized for size and power. Credit: Maya M. Lassiter
Robots small enough to travel autonomously through the human body to repair damaged sites may seem the stuff of science fiction dreams. But this vision of surgery on a microscale is a step closer to reality, with news that researchers from the University of Pennsylvania and the University of Michigan have built a robot smaller than a millimeter that has an onboard computer and sensors.
Scientists have been trying for decades to develop microscopic robots, not only for medical applications but also for environmental monitoring and manufacturing. However, they have faced formidable challenges. Existing microbots typically require large, external control systems, such as powerful magnets and lasers, and cannot make autonomous decisions in unfamiliar environments.
Overcoming obstacles
In a study published in the journal Science Robotics, the team describes how they overcame these obstacles to create an autonomous, programmable robot that's smaller than a grain of rice.
Two microrobots following a series of ID specific instructions, resulting in two different paths. (The video has been sped up by 10x). Credit: Maya Lassiter
The key breakthrough was moving the required computing power directly onto the robot's body, using the same semiconductor manufacturing techniques that make computer chips. This process, called Complementary Metal-Oxide-Semiconductor (CMOS), allows researchers to "print" all the components robots need onto their bodies and build hundreds of them at once on a single chip.
Each robot is about 210 to 270 micrometers wide, and all its systems are tightly integrated. These include onboard photovoltaic cells that capture light from external LEDs to power the system, a processor, sensors (for temperature) and actuators (for movement).
To prove that the tiny bot could sense, "think," and act for itself, the researchers set it on a thermal gradient challenge. They placed it in a fluid-filled lab dish, with one end cool and the other warm, and shone a light to power its photovoltaic cells continuously.
Zoomed out view of a microrobot climbing a temperature gradient using sensor feedback. The gradient is imposed by a Peltier pump held below the Petri dish. Once the robot aligns to the gradient, it alternates between arcing and turning motion to maintain a heading. Note, although the robot is traveling along the surface of a Petri dish, it projects a shadow through dish onto the paper sheet underneath (The video has been sped up by 200x). Credit: Maya Lassiter
Successful trials
The robot was programmed to sense the temperature and, if it was getting cooler, execute an arcing motion to search for warmer fluid. If the temperature was getting warmer, it would turn in the same place to stay in the warm spot. In total, 56 trials were conducted, and the robots successfully switched their movements autonomously.
The researchers noted that this breakthrough has numerous advantages: "Digital programming and onboard computing allow a single, general-purpose microrobot to carry out a range of tasks that can be reconfigured on demand, after fabrication."
Scientists build sub-millimeter-sized robots that can sense, 'think' and act on their own
Annotated images of the microscope setup. A: Front side of the microscope showing robots in solution with probes connected to a low-input-bias test circuit, fixed in micromanipulators. The robots are observed through a 4× microscope objective and imaged using a SciCam Pro camera. B: Back side of the microscope setup showing the CHROLIS light source, a breakout box enabling external control via the GUI, and the liquid light guide connection into the microscope. Credit: Maya M. Lassiter
And production doesn't have to be expensive, they added, "By moving computation to the microrobot, we reduce both the cost and operational overhead to a bare minimum, paving a path to widespread adoption."
There is still a lot to do before these bots are sent scurrying inside human bodies. One of the next goals for the researchers is to develop a fully integrated, wireless locomotion system that doesn't rely on an external light source for movement.
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More information: Maya M. Lassiter et al, Microscopic robots that sense, think, act, and compute, Science Robotics (2025). DOI: 10.1126/scirobotics.adu8009
Citation: Sub-millimeter-sized robots can sense, 'think' and act on their own (2025, December 15) retrieved 16 December 2025 from https://techxplore.com/news/2025-12-millimeter-sized-robots.html
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