Stiffness-Patterned Physically Intelligent Liquid Crystal Polymers for Self-Guided and Light-Fueled Multimodal Jumping

Living species use jumping to traverse complex terrains, inspiring soft robotic systems with embedded physical intelligence to mimic such motions. Among these, liquid crystalline polymers offer light-responsive, programmable deformation ideal for small-scale robotics. However, efficient energy release in snap-through motions is hindered by a trade-off between stiffness and initial curvature. Here, we present a light-triggered azobenzene-functionalized liquid-crystalline polymer (Azo-LCP) jumper that addresses this limitation through spatially patterned stiffness variation. By locally controlling photopolymerization time, cross-linking density was patterned within a monolithic film to create both soft regions with high photomechanical strain responsivity and rigid regions with enhanced stress accumulation.

Under uniform UV irradiation, the programmed stiffness mismatch controlled snap-through energy release and jumping mode. Asymmetric stiffness patterns broke structural symmetry and generated biased snap-through, enabling directional jumping through tilted energy release. A corner-rigid pattern achieved a horizontal jump distance of 25 mm and a vertical height of 28.7 mm. In contrast, a symmetric center-rigid pattern preserved high curvature while concentrating stress at soft-rigid interfaces, producing a maximum vertical jump height of 49 mm, equivalent to 24.5 body lengths. Simulations supported these stress accumulation and deformation mechanisms. Furthermore, combining a soft-rigid alternating pattern with geometric asymmetry enabled dual-mode actuation in a single Azo-LCP: blocking force-assisted vertical jumping and biased directional jumping. The dual-mode jumper reached 48.8 mm in height and 27.3 mm in distance and demonstrated sequential jumps under continuous UV exposure. This work establishes spatial stiffness programming as a material-level strategy for improving snap-through efficiency, symmetry breaking, and multimodal locomotion in light-driven soft actuators.