As reported in Science Robotics, Cornell University researchers have installed electronic "brains" on solar-powered robots that are smaller than an ant’s head. This enables them to walk autonomously without being externally controlled. Previously developed microscopic machines have been able to crawl, swim, walk and fold themselves up, but those have been externally controlled. To generate motion, wires or laser beams had to be used. But now, this innovation sets the stage for a new generation of microscopic devices that can track bacteria, sniff out chemicals, destroy pollutants, conduct microsurgery and scrub the plaque out of arteries.
The simple "brain" in the new robots is a circuit that contains a thousand transistors, plus an array of diodes, resistors and capacitors. The integrated CMOS circuit generates a signal that produces a series of phase-shifted square wave frequencies that in turn set the gait of the robot. The robot legs are platinum-based actuators. Both the circuit and the legs are powered by photovoltaics.
Eventually, the ability to communicate a command will allow users to give the robot instructions, and the internal brain will figure out how to carry them out. That permits the user to have a conversation with the robot. The robot might tell the user something about its environment, and then the user might react by telling it, 'OK, go over there and try to find out what’s happening."
The new robots are approximately 10,000 times smaller than macroscale robots that feature onboard CMOS electronics, and they can walk at speeds faster than 10 micrometers per second. The fabrication process enables researchers to outfit microscopic robots with their own apps - ranging from chemical detectors to photovoltaic "eyes" that help robots navigate by sensing changes in light.
This lets researchers imagine really complex, highly functional microscopic robots that have a high degree of programmability, integrated not only with actuators, but with sensors. The Cornell team is excited about applications in medicine and in environmental remediation, where robots that know how to sense dangerous chemicals or cells and get rid of them.