Researchers Build Autonomous Robots Smaller Than a Grain of Salt

Researchers from University of Pennsylvania and University of Michigan have built what they describe as the world's smallest fully autonomous robots. The devices are small enough to operate at the scale of biological cells, measuring roughly 200 × 300 × 50 micrometers, about one-tenth the width of a millimeter.

Despite their size, the robots are self-contained. Each unit can move, sense its environment, perform basic computation, and respond without external control, tethers, or magnetic guidance. According to the researchers, the robots are also inexpensive to manufacture, costing around one cent per unit.

The work was led in part by Marc Miskin, an assistant professor of electrical and systems engineering, who noted that these robots are orders of magnitude smaller than previous micro-robotic systems. Their size places them in the same range as many microorganisms, which opens up research possibilities that larger robots cannot reach.

The findings were published in Science Robotics and Proceedings of the National Academy of Sciences, detailing how the robots integrate power, logic, and movement into a structure smaller than a grain of salt. The robots are designed to survive and operate autonomously for extended periods, potentially lasting months under the right conditions.

Researchers suggest long-term applications could include tracking the behavior of individual cells, studying microscopic environments, or assisting in the construction of microscale machines. Because the robots function at the same physical scale as biological systems, they may eventually be able to navigate tissue or lab-grown environments that are inaccessible to existing tools.

This research remains experimental. There is no consumer-facing application, and practical use outside laboratory settings is still theoretical. The work represents a technical milestone rather than a deployable technology, highlighting how far miniaturization and autonomous control have progressed rather than signaling an imminent product or service.