A collaboration led by scientists at Cornell has created the first microscopic robots that incorporate semiconductor components able to be controlled by standard electronic signals. The tiny robots are also able to walk thanks to that electronic signal. Researchers say that the robots are roughly the size of paramecium and provided a template for building more complex versions of themselves that utilize silicon-based intelligence to be mass-produced.
Someday this type of robot could travel through human tissue and blood. These robots are the latest iteration of previous nanoscale creations from researchers, including microscopic sensors and graphing-based origami machines. The paramecium-sized robots are about five microns thick, 40 microns wide, and vary from 40 to 70 microns.
Each robot has a simple circuit made from silicon photovoltaic that functions as the robot’s torso and brain along with four electrochemical actuators that function as legs. Creating the tiny robot’s legs was very difficult. There were no minuscule electrically activatable actuators that can be used for the robots, so the researchers had to invent them and combine them with the electronics.
Atomic layer deposition and lithography were used to construct the legs from platinum strips only a few dozen atoms thick with a thin layer of inert titanium on one side. When a positive electric charge is applied to the platinum, negatively charged ions absorb into the exposed surface of the surrounding solution to neutralize the charge. The ions force the platinum to expand, making the strip bend.
The strips of platinum used for the legs are so thin that they can bend sharply without breaking. To control the motion of the limbs, researchers used rigid polymer panels on top of the strips. Gaps between the panels function like a knee or ankle, allowing the legs to be bent in a controllable manner.
The robots are controlled by flashing laser pulses at different photovoltaics charging up separate sets of legs. The robot can walk when the laser is toggled back and forth between the front and back photovoltaics. The little bots required a very low 200 millivolts voltage and only 10 nanowatts of power. The team is currently exploring ways to improve the robots to create swarms of microscopic robots that can crawl inside the human body to repair damage and act as probes.