Taking inspiration from caterpillars, North Carolina State University researchers have developed a soft robot that is capable of moving forward and backward and dipping under narrow spaces.

Enabling the so-called caterpillar-bot to do that is a network of silver nanowires that rely on heat to guide how the device bends. This, according to its developers, enables operators to steer the robot.

Source: North Carolina State University

To mimic the biomechanics of a caterpillar whose movements are controlled by the local curvature of its body — which curves differently when it pulls itself forward than it does pushing itself backward — the team used nanowire heaters to control the robot’s replicated curvature and movement.

"Engineering soft robots that can move in two different directions is a significant challenge in soft robotics," the researchers explained. "The embedded nanowire heaters allow us to control the movement of the robot in two ways. We can control which sections of the robot bend by controlling the pattern of heating in the soft robot. And we can control the extent to which those sections bend by controlling the amount of heat being applied.”

According to its developers, the caterpillar-bot is composed of two layers of polymer that react differently when exposed to heat — with the bottom layer shrinking, or contracting, in the presence of heat and the top layer expanding when exposed to heat.

The network of silver nanowires was embedded in the expanding layer of polymer and featured lead points where operators can apply an electric current and thus control which sections of the bot will move.

Using this approach in the lab, the researchers demonstrated that the caterpillar-bot could pull itself forward and push itself backward. Further, the researchers demonstrated that they could steer the robot under narrow gaps — under a door, for instance.

The researchers suggest that the robot could one day be used in the making of search and rescue devices.

An article detailing the development, "Caterpillar-Inspired Soft Crawling Robot with Distributed Programmable Thermal Actuation," appears in the journal Science Advances.

For more information, watch the accompanying video that appears courtesy of North Carolina State University.