Biohybrid Crawling Robot With Spiral‐Spring Backbone and Inclined Legs for Enhanced Locomotion

ABSTRACT Biohybrid robots powered by muscle tissues offer flexibility and silent actuation, and ring‐shaped muscle tissues (muscle rings) are promising modular actuators. However, locomotion in muscle‐ring‐driven robots remains limited by bending resistance and leg geometry of their skeletons. At reliably printable dimensions, straight‐beam backbones resist bending and restrict muscle‐driven deformation. Thinning the beam increases bending compliance but reduces torsional stiffness and conflicts with fabrication limits. Predominantly vertical legs, oriented perpendicular to the substrate, limit conversion of contraction–relaxation cycles into directional displacement. Here, we present a biohybrid crawling robot combining two complementary structural elements. Compared with a straight beam producing the same bending displacement, the spiral‐spring backbone maintains a larger, printable cross‐section and exhibits greater resistance to unintended torsional deformation, supporting axial postural stability. This geometry facilitates transmission of muscle‐generated force into large‐amplitude body deformation. Additionally, outward‐inclined legs with unequal front–rear lengths introduce phase‐dependent frictional anchoring that converts cyclic deformation into directional strides. Integrating these elements, the robot achieved a forward speed of 2.0 mm s − 1 (14 body lengths per minute), exceeding those of previously reported muscle‐powered crawling and walking robots. These results establish a structural design principle that balances bending compliance, torsional resistance, printability, and directional anchoring to improve biohybrid locomotion.