Electronic “Brains” Enable Smart Microrobots to Walk

A team of researchers at Cornell University has installed electronic “brains” on solar-powered robots that measure only 100 to 250 micrometers in size, enabling them to walk autonomously without being externally controlled. 

The new research paper titled “Microscopic Robots with Onboard Digital Control,” was published in Science Robotics. 

Groups of researchers have already developed microscopic machines that have the ability to crawl, swim, fold themselves up, and more. However, wires were always used to generate motion and provide electrical current, or laser beans had to be focused on specific locations of the robots. 

Itai Cohen is a professor of physics. 

“Before, we literally had to manipulate these ‘strings’ in order to get any kind of response from the robot,” Prof. Cohen says. “But now we have these brains on board, it’s like taking the strings off the marionette. It’s like when Pinocchio gains consciousness.” 

The new developments could help usher in a new generation of microscopic devices that can do things like track bacteria, identify chemicals, combat pollutants, and much more. 

The team included researchers from the labs of Cohen, Alyosha Maoinar, associate professor of electrical and computer engineering; and Paul McEuen, a professor of physical science. The lead author of the paper is postdoctoral researcher Michael Reynolds. 

What is the Electronic “Brains” 

The electronic “brain” the team is talking about is a complementary metal-oxide-semiconductor (CMOS) clock circuit that consists of a thousand transistors and an array of diodes, resistors, and capacitors. With the integrated CMOS circuit, a signal can be generated to produce a series of phase-shifted square wave frequencies that set the gait of the robot. The robot’s legs are platinum-based actuators, and both the circuit and legs are powered by photovoltaics. 

“Eventually, the ability to communicate a command will allow us to give the robot instructions, and the internal brain will figure out how to carry them out,” Cohen said. “Then we’re having a conversation with the robot. The robot might tell us something about its environment, and then we might react by telling it, ‘OK, go over there and try to suss out what’s happening.’” 

Macroscale robots that have onboard CMOS electronics are around 10,000 times bigger than this newly developed robot, which can also walk at speeds faster than 10 micrometers per second. 

The innovative fabrication process developed by the team has led to a platform that can help other researchers outfit microscopic robots with their own apps, which could include chemical detectors or photovoltaic “eyes” that help robots navigate by sensing light changes. 

“What this lets you imagine is really complex, highly functional microscopic robots that have a high degree of programmability, integrated with not only actuators, but also sensors,” Reynolds said. “We’re excited about the applications in medicine — something that could move around in tissue and identify good cells and kill bad cells — and in environmental remediation, life if you had a robot that knew how to break down pollutants or sense a dangerous chemical and get rid of it.”