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This Robot is Tinier than a Grain of Salt

Engineers had been trying to solve this problem for 40 years

11:00 AM CST on December 30, 2025

A microrobot, fully integrated with sensors and a computer, small enough to balance on the ridge of a fingerprint. Credit: Marc Miskin, Penn.

This isn’t a speck of dust—you’re looking at the world’s tiniest autonomous, programmable robot. This miniscule gizmo could eventually be harnessed to inspect the intricacies of living systems, perform surgery, and deliver drugs.

The wee robots are smaller than a grain of salt, measuring around 200 by 300 by 50 micrometers. That’s 10,000 times smaller than other “programmable, autonomous robots that sense, think, and act,” according to a paper published in Science Robotics. 

These astonishingly tiny robots move about by nudging their surroundings. Credit: Lucas Hanson and William Reinhardt, University of Pennsylvania.

While researchers have managed to shrink the size of many electronics over the past few decades, robots pose a unique challenge. “Building robots that operate independently at sizes below one millimeter is incredibly difficult,” said paper author Marc Miskin, a professor of electrical and systems engineering at the University of Pennsylvania, in a statement. “The field has essentially been stuck on this problem for 40 years.”

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While traversing the human body, any petite robot must contend with significant drag as it moves through fluid. In this environment, Miskin likened the movement of small objects through water to “pushing through tar.” This means that elements used by bigger bots to get around, like legs and arms, won’t cut it. Instead, the scientists figured out a way to move the robot’s environment.

Read more: “Why Animals Run Faster than Robots”

These diminutive devices create an electrical field that moves the ions in surrounding liquid, which then knock around nearby water molecules. By tinkering with the electrical field, operators can tailor the bot’s movements and coordinate them in groups. They run on pulses from LED lights, and can swim for months at a time.

To think for themselves, these bots need a teeny computer. This enables them to measure and report temperatures throughout the body, which holds clues to the health of cells. Co-author David Blaauw, an electrical engineer at the University of Michigan, previously helped create the world’s smallest computer. He and his team used this know-how to develop a system for the robot that requires little power to run and squeezes the memory, processor, and sensors into less than a millimeter of space.

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Now, the team hopes to craft versions of the robots that can swim more swiftly and incorporate additional sensors, among other feats. Currently, they cost a penny each to make, and they’re highly customizable, paving the way for new tiny but mighty innovations. “This is really just the first chapter,” Miskin said. “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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Lead image: Marc Miskin, Penn

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