High-Modulus Homochiral Torsional Oxide Ceramic Artificial Muscles

Artificial muscles are soft actuators used to mimic human muscle movements, but using oxide ceramics to fabricate high-modulus artificial muscles is a challenge since they are prone to fracture during homochiral torsion. Here, we report a strategy of ceramic metallization to solve the problem of low-shear and low-stretchability of ceramics and fabricate homochiral coiled alumina yarn artificial muscles with a solenoid structure. The alumina muscle can carry objects of 0.28 million times its own weight and provide a high actuation stress of 483.5 MPa while maintaining a large tensile stroke of 13.5%. In addition, it shows a contraction power 18 times and an energy density 240 times of human muscles, as well as a high energy conversion efficiency of 7.59% under an electric drive mode, which far exceed most reported polymer and carbon muscles. This work realizes large-scale fabrication of high-modulus ceramic muscles.