Imagine being chased by a swarm of robots that just would not stop no matter how many of its parts have already been destroyed.

It sounds like a scene from science fiction, but the technology is starting to become a reality, courtesy of researchers at Columbia University and the Massachusetts Institute of Technology.

'Gray Goo' Robots

In a study featured in the journal Nature, a team from Columbia engineering and MIT developed cell-inspired "particle robots" capable of moving together as a collective.

Individually, these tiny robots can only perform simple functions such as slightly expanding and contracting. They are not capable of moving independently.

However, when thousands of them a grouped together in a "sticky" cluster and made to oscillate in response to a light source, the particle robots can move forward slowly, toward where the light is coming from.

Hod Lipson, a professor at Columbia and one of the authors of the study, likened their new robot creation to the proverbial "gray goo".

"Our robot has no single point of failure and no centralized control," Lipson said. "It's still fairly primitive, but now we know that this fundamental robot paradigm is actually possible."

Lipson and his colleagues believe their research can help explain why cells cannot move individually but they can do so when they are grouped together.

Creating Biological Robots

Scientists have developed different kinds of autonomous robots before, but many of them are non-biological machines that are not capable of growing or healing themselves from damage.

On the other hand, the Columbia and MIT researchers worked on creating tiny but robust robots that can continue functioning even when some of their parts have already begun to fail.

Lipson said they have been trying to rethink their approach to robotics to come up with a different way to build machines.

Their goal is not just to make robots look more biological but to actually develop them with a biological system. They want to build robots that are "vast in complexity and abilities" but are made of simple components.

Daniela Rus, director of MIT's Computer Science & Artificial Intelligence Laboratory (CSAIL) and co-author of the study, explained how they drew inspiration from cells that make up living organisms. The team wanted to know if they could develop robotic cells that can be used to make different kinds of robots.

The robots that the team had in mind could be given shapes to suit different tasks, such as something that can crawl through tunnels like a snake, or a three-handed machine that be used for a factory floor. These particle robots can also be made to build themselves.

"Suppose, for example, that a robot needs a screwdriver from the table-the screwdriver is too far to reach," Rus said. "What if the robot could reshuffle its cells to grow an extra long arm? As its goals change, its body can change too."

The Columbia and MIT researchers worked with colleagues from Harvard University and Cornell University to create identical components, also known as particles, that make up the tiny robots.

The researchers used robots made up of only two dozen particles for experiments, while they used machines made up of 100,000 particles for simulations.

When the robots were exposed to a light source, particles that were closer to the light started their cycle earlier, the team said. This activity creates a wave throughout the cluster of robots, allowing them to move closer to the light as a collective.

Lipson, Rus, and their colleagues have begun testing their new robot system using a larger number of particles. They are also looking at how they can create other forms using the machines, such as vibrating microspheres.