Scientists have developed robots smaller than a grain of salt that can sense their environment, make decisions, and move independently.
Measuring about 200 by 300 by 50 micrometers, the tiny machines are nearly invisible to the naked eye. Despite their size, they are fully autonomous and programmable, able to swim through liquids, detect temperature changes, and follow preset paths without any external control.
Created by researchers at the University of Pennsylvania and the University of Michigan, the robots mark a major advance in microscopic robotics. Unlike earlier designs, they don’t rely on wires, magnets, or outside power sources. Instead, each robot runs entirely on light through miniature solar panels and contains a tiny onboard computer, allowing it to process information and operate for months at a time. Each unit costs roughly one cent to produce.
Rather than using motors or moving parts, the robots move by generating small electric fields that push charged particles in the surrounding liquid. This motion pulls nearby water along, enabling the robots to swim and steer — a method well suited for tiny scales where traditional mechanics fail.
Each robot also includes sensors, memory, and a processor. Its temperature sensor can detect changes as small as one-third of a degree Celsius. Without wireless transmitters, the robots communicate by making subtle movements that researchers record and decode under a microscope. The same light source that powers them is also used to program them, allowing each robot to receive unique instructions.