American engineers developed the world’s tiniest programmable autonomous robots. The size of each one is around 200 $\times$ 300 micrometers with a thickness of about 50 micrometers—meaning they are comparable in magnitude to individual human body cells. But even more astonishing is that these microscopic devices can function completely independently.
Each robot contains its own computer—a kind of miniature “brain”—including a processor, memory, sensors, and solar panels powered by a tiny 75-nanowatt LED. This is more than enough for the robot to operate for months under favorable conditions.
These machines have neither legs nor arms. Instead, they create an electric field around a line of electrodes and use it to move water molecules in the surrounding fluid, thereby propelling themselves forward. The travel speed is approximately one body length per second, and with a large quantity, such robots can “swim” in unison, resembling a school of fish.
Control is executed via light impulses. Each robot has a unique address, which allows instructions to be uploaded to individual devices as well as entire groups. They exhibit exceptional sensitivity and can detect temperature changes of just one-third of a degree Celsius. Researchers even programmed them to seek heat sources and transmit data using specific “wobbles” that encode information.
Equally remarkable is their production method. A standard microchip fabrication process—the same one used for manufacturing large computers—was utilized to create the robots. Because of this, the cost was extremely low: in mass production, one robot costs only a single cent. The control system is also very simple and is based on off-the-shelf components—such as a Raspberry Pi and a smartphone camera.
Currently, the robots are being tested in a weak hydrogen peroxide solution, but engineers are already considering safer liquids for future medical applications. Researchers believe that such devices could be employed to monitor the condition of individual cells by temperature changes or for targeted delivery of therapeutic effects to necessary body areas.
The reliability of the design also deserves special attention: the absence of moving parts significantly reduces the risk of malfunctions. The robots can be captured and moved with a pipette without damage. Such developments open up the possibility of working at previously inaccessible scales. Observing individual cells may yield invaluable insights into diseases, and mastering the microscopic level of construction could lead to the creation of more advanced electronics and even fundamentally new materials.
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