Graphene-Based Actuators Flex With Current

To develop new materials for robotics, Chinese scientists have developed graphene-based actuators that convert electricity into motion (ACS Nano, DOI: 10.1021/nn3006812). In robots, actuators act like muscles, driving the movement of mechanical limbs. Most electromechanical actuator materials, such as ceramics and conductive polymers, respond slowly, require a lot of power, or provide very little force. To make speedier, strong actuators, Nankai University researchers led by Yongsheng Chen and Yi Huang coated graphene paper with polydiacetylene. Graphene provides a highly conductive, flexible backing for the brittle crystalline polymer, which deforms in response to electric current. The researchers can cut the actuator sheet into arbitrary shapes and wire it to an electrical source. In response to alternating current, the material can swing back and forth 200 times per second. When the scientists apply direct current, the material generates 160 megapascals of stress per gram of material, making it stronger than most polymers. Using a sheet of the material, the team made a simple inchworm robot that arches and relaxes to crawl forward, slowly but surely, at about 0.25 mm per second.