Biocompatible Liquid Crystal Elastomer Optical Fiber Actuator for In Vivo Endoscopic Navigation and Laser Ablation Therapy

Photothermal-responsive liquid crystal elastomers (LCEs) face critical barriers in biomedical applications: phase transition temperatures exceeding 80 °C risk thermal injury, and free-space optical actuation fails in confined spaces. Here, a thiol-ene crosslinked LCE is developed with a biocompatible phase transition temperature (37.6 °C), enabling safe actuation within biological tissues. Through coaxial extrusion, the fabrication of waveguide-structured LCE optical fibers is pioneered, achieving ultralow optical loss (0.76 dB cm^-1) and enabling long-range light transmission and remote actuation via silica optical fiber coupling. Under 808 nm laser stimulation (375 mW), these LCE optical fibers generate 30% contraction strain in 23 s, maintaining maximum surface temperature < 48 °C. Integrated into an endoscopic system, LCE optical fibers replaced rigid mechanical components. Ex vivo characterization reveals their omnidirectional bending capability (94° angular range), while in vivo trials on live rats and rabbits validate their operational functionality in anatomical environments, enabling hemorrhage detection and laser-steered tumor ablation via controlled navigation. Histopathological analysis confirms no thermal damage at fiber-tissue interfaces. This work establishes biocompatible LCE optical fibers as a photonic platform integrating photonic-driven soft actuation and tissue-compliant adaptability, enabling mechanically safe interventions in confined anatomical environments.