Centimeter-Scale Bulk Liquid Crystal Elastomer Artificial Muscle with Strong Mechanical Properties and Designable Complex Shape-Morphing

Abstract

Artificial muscles are regarded as indispensable for next-generation robots. They can mimic the complex motions of living organisms and demonstrate performance surpassing that of natural muscles. Liquid crystal elastomers (LCEs) possess the unique advantage of programmable three-dimensional shape-morphing compared to other soft materials, holding significant promise for artificial muscle applications. However, LCE-based artificial muscle with designable shape-morphing is limited to 100 μm thickness currently, which significantly restricts the driving capability of artificial muscles. Here, we developed the centimeter-scale bulk LCE (CBLCE) artificial muscles with all three dimensions up to centimeter-scale through two-step crosslinking of an LCE with acceptable actuation strain and large modulus, which results in CBLCE artificial muscles with strong mechanical properties. Specifically, this CBLCE demonstrates 37.5% actuation strain (comparable to human skeletal muscles) and strong mechanical properties, such as up to 24 MPa modulus (exceeding that of most powerful natural muscles), large energy density (10 times that of human skeletal muscle), and large output capability (3624 times its gravity). Beyond these remarkable mechanical properties, this artificial muscle further demonstrates designable complex three-dimensional shape-morphing. The developed CBLCEs hold great promise for advancing artificial muscle applications in soft robotics, expanding their potential for broader applications.