Nanotechnology continues to get smaller, but researchers at Massachusetts Institute of Technology (MIT) took tiny robotics to a new level. The university might have created the tiniest robots to date capable of sensing their environments.
The 'impossibly small' robots are only the size of a human egg cell can store data and even compute. They consist of small electronic circuits made of two-dimensional materials and leverage colloids to help power the systems.
Colloids are only a billionth to a millionth of a meter large, and they're insoluble particles or molecules suspended in a substance. The most common colloid humans know of is milk, which has small globules of fat and protein that don't settle out.
The researchers coupled those colloids to the circuitry used in the robots to carry out commands. The team hopes to one day use the tiny robots in devices that could be sent on diagnostic journeys -- like being sent through the human body, an oil pipeline, or through tubes in a chemical refinery.
“We wanted to figure out methods to graft complete, intact electronic circuits onto colloidal particles,” explained Michael Strano, the Carbon C. Dubbs Professor of Chemical Engineering at MIT. Strano served as senior author of the study, which was published today in the journal Nature Nanotechnology. MIT postdoc Volodymyr Koman served as the paper’s lead author.
“Colloids can access environments and travel in ways that other materials can’t,” Strano said. Things like dust particles can travel theoretically forever in the air because they're small enough to constantly collide with air molecules.
Strano noted other research teams have worked on molecularly small devices. However, those teams worked on controlling the movement of those robots on an individual scale rather than figuring out how to move those tiny robots en masse.
The robots developed by MIT are self-powered and require no internal batteries. A photodiode gives enough electricity to the tiny robotic circuits to power them. It's just enough for the robots to make sense of their environments, power computational and memory circuits.
Conventional chips, like the silicon-based ones most often associated with electronics, have flat substrates. Those wouldn't do as well when dealing with colloids. The researchers called conventional chips "energy-thirsty." Hence the researchers' need for a two-dimensional solution. The team combined the supermaterial graphen and a transition metal dichalcogenides and found it to be the perfect pair for interacting with colloids.
“They can be powered by nanowatts with subvolt voltages,” Koman said.
The 2-D electronics still need the colloids to fully function, even on "unconventional substrates," Korman noted.
“They can’t exist without a substrate,” Strano said. “We need to graft them to the particles to give them mechanical rigidity and to make them large enough to get entrained in the flow.”
The team acknowledge that their nanoscale robotics "haven't reached that level" of becoming advanced electronics.
"We see this paper as the introduction of a new field" in robotics, Strano said.