The world’s smallest fully programmable, autonomous robots have launched, able to sense temperature, navigate complex patterns, and measure just 0.2 millimetres wide.
Created by researchers at the University of Pennsylvania and the University of Michigan, the microscopic machines cost just one penny each and operate for months using light power.
The bots combine a sub-millimetre computer “brain” developed at U-M with a propulsion system from Penn that addresses the physics challenges of microscale motion.
“We’ve made autonomous robots 10,000 times smaller,” said Marc Miskin, assistant professor in electrical and systems engineering at Penn. “That opens up an entirely new scale for programmable robots.”
Swimming through tar
Movement at the microscale faces unique challenges due to drag and viscosity, which Miskin compares to swimming through tar.
To overcome this, the robots use a propulsion system with no moving parts. Instead of pushing themselves, they generate an electrical field that nudges ions in the surrounding liquid, which in turn pushes nearby water molecules to generate force.
This mechanism allows the 0.2 by 0.3 millimetre bots to operate without the mechanical wear that typically limits micro-robot lifespan.
The robots run on just 75 nanowatts of power — roughly 100,000 times less than a smartwatch requires — using solar panels that cover most of their surface.
This extreme power constraint required a complete redesign of how the robots process information.
“We had to totally rethink the computer program instructions, condensing what conventionally would require many instructions for propulsion control into a single, special instruction to help us shrink the program’s length to fit in the robot’s tiny memory,” said David Blaauw, professor of electrical and computer engineering at U-M.
Waggle dance
The current generation of robots can detect temperature changes within a third of a degree Celsius, reporting their findings by wiggling like a honeybee’s “waggle dance”.
Researchers believe these capabilities could enable applications in medicine, such as monitoring the health of individual cells, or in manufacturing microscale devices.
“This is really just the first chapter,” Miskin said. “We’ve shown that you can put a brain, a sensor and a motor into something almost too small to see, and have it survive and work for months.”
