Researchers have produced the world’s smallest fully programmable, autonomous robots, measuring about 0.2 by 0.3 by 0.05 millimeters — a scale comparable with many microorganisms. The light-powered machines receive both energy and programming from pulses of light. Each robot has a unique identifier, allowing individual devices to receive different instructions. A batch described in Science Robotics carries temperature sensors accurate to within a third of a degree Celsius. The robots report measured temperatures by wiggling, a motion likened to the waggle dance of honeybees.
Propulsion and computing were developed by separate teams that later joined their efforts. Marc Miskin, assistant professor in electrical and systems engineering at the University of Pennsyvlania, is senior author on studies in Science Robotics and the Proceedings of the National Academy of Sciences. David Blaauw and Dennis Sylvester, professors of electrical and computer engineering at UM, contributed ultra-small computing designs and are senior authors of the Science Robotics study.
Moving at the microscale in water is difficult because drag and viscosity dominate. The team’s propulsion avoids moving parts: the robots generate an electrical field that nudges ions in the surrounding liquid, and those ions push nearby water molecules to produce force. Blaauw’s team ran the robot program on 75 nanowatts, which the researchers say is 100,000 times less than a smart watch requires. Solar panels take up most of the robot to collect that energy, and engineers condensed control instructions into a single special instruction so programs fit very small memory.
Researchers say the devices could advance medicine by monitoring the health of individual cells and help manufacturing by building microscale devices. Future versions could store more complex programs, move faster, add new sensors, or operate in different environments.
- Primary support: National Science Foundation
- Additional support: University of Pennsylvania Office of the President, Air Force Office of Scientific Research, Army Research Office, Packard Foundation, Sloan Foundation, Fujitsu Semiconductors
Difficult words
- autonomous — able to operate without external control
- programmable — able to receive and run different instructions
- propulsion — method or force that makes movement
- viscosity — measure of a liquid's resistance to flow
- ion — an atom or molecule with electric chargeions
- nanowatt — one billionth of a watt of powernanowatts
- identifier — a code that uniquely names an individual device
- condense — to make something shorter or more compactcondensed
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could tiny robots that monitor individual cells change medical diagnosis or treatment? Give reasons or examples from the article.
- What practical challenges or risks might arise when using microscopic robots inside living bodies or in manufacturing settings?
- Which possible improvement mentioned in the article (more complex programs, faster movement, new sensors, or different environments) do you think is most important, and why?
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