Light-Actuated Fiber-Climbing Inchworm Robot Toward Endoluminal Navigation

Light-responsive materials provide unique properties for developing remotely controllable and scalable soft robotic systems. Nevertheless, conventional light-driven systems require a direct line-of-sight and suffer from limited optical field penetration, restricting their use when considering applications in clinically relevant environments. In this work, we address these limitations by integrating wavelength-selective liquid crystalline elastomer (LCE) soft actuators with a tailored side-emitting optical fiber as an endoluminal-compatible platform. The fiber redistributes the input optical energy to the side output, enabling wavelength-selective actuation in individual segments of the soft robot body, and providing physical guidance for controlled locomotion along its surface. Beyond the conventional designs that typically integrate LCEs at the waveguide distal tip only for tip steering or gripping tasks, our system comprises a kirigami-engineered 3D cylindrical architecture fitting around the fiber, and a light-locking mechanism enabled by photothermal deformation of LCEs. This design permits wavelength-selective step motion and amplified out-of-plane deformation for enhanced locomotive efficiency. We show that programmed temporal illumination patterns result in controllable inchworm-like locomotion. This line-of-sight-independent locomotion is suited for future applications in confined endoluminal environments.