Scientists build autonomous robots smaller than a grain of salt
Researchers have developed microscopic, light-powered robots capable of thought, movement, and prolonged survival. These robots, measuring approximately 200 by 300 by 50 micrometers, are smaller than a grain of salt and can operate for months. They represent the first truly autonomous robots at this scale.
The robots function without wires, magnetic fields, or external controls. They can swim by manipulating electric fields, detect temperature changes, and collaboratively execute tasks. Each unit costs approximately $0.01 to produce.
Unlike conventional robots that rely on gravity and inertia, these microscopic devices navigate environments where surface-related forces, such as drag and viscosity, dominate. Their propulsion method involves generating an electrical field that moves charged particles in the surrounding liquid, thereby creating a localized current that propels the robot.
The University of Pennsylvania and University of Michigan teams collaborated on this project. The University of Michigan’s contribution focused on integrating computing capabilities onto the miniature scale. The robots include microcomputers that allow them to follow programmed paths and adjust their movement. They can reach speeds of up to one body length per second.
Power is supplied by light from an LED, generating 75 nanowatts. Specialized circuits were designed to operate at extremely low voltages, reducing power consumption by over 1000 times compared to conventional electronics. The robots’ software was re-engineered to fit into a minimal memory space.
These robots contain electronic temperature sensors capable of detecting changes as small as one-third of a degree Celsius. This allows them to identify warmer regions or report temperature values. Communication of these measurements occurs through programmed “dances” that encode data, which is then decoded via microscopic observation.
The same light source that powers the robots also programs them. Each robot has a unique address, enabling researchers to upload specific instructions to individual units.