Researchers at Cornell University, in collaboration with Northwestern University, have achieved a significant breakthrough in the development of tiny, soft robots powered by methane-fueled internal combustion engines. These miniature quadruped robots, less than an inch in size, possess impressive capabilities, including jumping nearly two feet in the air.
Small-sized robots have garnered increasing attention due to their potential applications in diverse fields, from military to healthcare. However, miniaturizing robots presents challenges, such as power generation and payload capacity limitations, often due to the constraints of conventional batteries.
Hydrocarbon molecules, with energy densities 20-50 times higher than the best batteries, offer a solution to this problem. These molecules can be scaled down without requiring extensive redesign, making them ideal for miniature robots. The research team, led by Robert Shepherd, specializes in organic control of robots and recently developed a tiny robot measuring just 29 mm in length but capable of leaping up to 59 cm in the air.
The key innovation lies in the robot’s power source—an internal combustion chamber fueled by methane. In just half a millisecond after methane combustion, the chamber inflates like a balloon, generating 9.5 newtons of force and allowing for rapid, repeated motion. By combining two of these microactuators, the researchers created a quadruped robot.
Remarkably, these microactuators are incredibly small, weighing only 325 milligrams and a quarter of a penny’s size. This size reduction was achieved by relocating essential components outside the robot, such as fuel mixing, oxygen supply, and combustion ignition. To ensure safety, the researchers added fire-resistant elastomers and flame arrestors to prevent the actuator from exploding. This design allows the tiny actuator to endure 750,000 operation cycles at 50 Hz.
Controlling gas pressure enables precise movement control of the quadruped robot. Firing both actuators propels the robot forward while firing only one can rotate it. Ongoing research focuses on refining the technology to enable the robot to decelerate effectively.
Importantly, this breakthrough is not limited to small robots; the researchers envision applying tiny actuators to more giant robots, providing them with individual muscles akin to a robotic arm. This innovation opens up new possibilities for enhancing the agility and versatility of larger robotic systems.
The research findings have been published in the journal Science, marking a significant advancement in the field of soft robotics and miniature internal combustion engines.